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Marie S, Frost KL, Hau RK, Martinez-Guerrero L, Izu JM, Myers CM, Wright SH, Cherrington NJ. Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients. Acta Pharm Sin B 2023; 13:1-28. [PMID: 36815037 PMCID: PMC9939324 DOI: 10.1016/j.apsb.2022.08.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 12/18/2022] Open
Abstract
The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.
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Affiliation(s)
- Solène Marie
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Kayla L. Frost
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Raymond K. Hau
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Lucy Martinez-Guerrero
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Jailyn M. Izu
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Cassandra M. Myers
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA
| | - Stephen H. Wright
- College of Medicine, Department of Physiology, University of Arizona, Tucson, AZ 85724, USA
| | - Nathan J. Cherrington
- College of Pharmacy, Department of Pharmacology & Toxicology, University of Arizona, Tucson, AZ 85721, USA,Corresponding author. Tel.: +1 520 6260219; fax: +1 520 6266944.
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Tsermpini EE, Serretti A, Dolžan V. Precision Medicine in Antidepressants Treatment. Handb Exp Pharmacol 2023; 280:131-186. [PMID: 37195310 DOI: 10.1007/164_2023_654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Precision medicine uses innovative approaches to improve disease prevention and treatment outcomes by taking into account people's genetic backgrounds, environments, and lifestyles. Treatment of depression is particularly challenging, given that 30-50% of patients do not respond adequately to antidepressants, while those who respond may experience unpleasant adverse drug reactions (ADRs) that decrease their quality of life and compliance. This chapter aims to present the available scientific data that focus on the impact of genetic variants on the efficacy and toxicity of antidepressants. We compiled data from candidate gene and genome-wide association studies that investigated associations between pharmacodynamic and pharmacokinetic genes and response to antidepressants regarding symptom improvement and ADRs. We also summarized the existing pharmacogenetic-based treatment guidelines for antidepressants, used to guide the selection of the right antidepressant and its dose based on the patient's genetic profile, aiming to achieve maximum efficacy and minimum toxicity. Finally, we reviewed the clinical implementation of pharmacogenomics studies focusing on patients on antidepressants. The available data demonstrate that precision medicine can increase the efficacy of antidepressants and reduce the occurrence of ADRs and ultimately improve patients' quality of life.
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Affiliation(s)
- Evangelia Eirini Tsermpini
- Pharmacogenetics Laboratory, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Alessandro Serretti
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Vita Dolžan
- Pharmacogenetics Laboratory, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
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Najmi AA, Bischoff R, Permentier HP. N-Dealkylation of Amines. Molecules 2022; 27:molecules27103293. [PMID: 35630770 PMCID: PMC9146227 DOI: 10.3390/molecules27103293] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/03/2022] [Accepted: 05/08/2022] [Indexed: 02/01/2023] Open
Abstract
N-dealkylation, the removal of an N-alkyl group from an amine, is an important chemical transformation which provides routes for the synthesis of a wide range of pharmaceuticals, agrochemicals, bulk and fine chemicals. N-dealkylation of amines is also an important in vivo metabolic pathway in the metabolism of xenobiotics. Identification and synthesis of drug metabolites such as N-dealkylated metabolites are necessary throughout all phases of drug development studies. In this review, different approaches for the N-dealkylation of amines including chemical, catalytic, electrochemical, photochemical and enzymatic methods will be discussed.
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Schuh MJ, Crosby S. Chronic Anticholinergic Toxicity Discovered in a Pharmacogenomics, Polypharmacy Patient. Sr Care Pharm 2021; 36:304-310. [PMID: 34016227 DOI: 10.4140/tcp.n.2021.304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To report a case of chronic anticholinergic toxicity in a referred, pharmacogenomics (PGx), polypharmacy patient. SUMMARY The patient is a 67-year-old male who was referred to the polypharmacy service for a PGx consult. This patient has had episodic fever of unknown origin, general cutaneous vasodilation, tremors, jerks, and brain fogginess which have been unexplained. He has seen specialists from infectious disease, rheumatology, endocrinology, and neurology with no contributory condition causing these symptoms, so he was referred for PGx testing and evaluation by the polypharmacy pharmacist. CONCLUSION This case demonstrates the importance of pharmacist-patient consultations and how a PGx consult may expose polypharmacy medicationrelated problems of greater significance than the PGx indication for the consult. In addition, the case demonstrates positive interprofessional collaboration between pharmacists and physicians to more effectively solve complex medication-related problems that may not be easily diagnosed through objective lab or diagnostic testing.
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Ikejiri K, Akama Y, Ieki Y, Kawamoto E, Suzuki K, Yokoyama K, Ishikura K, Imai H. Veno-arterial extracorporeal membrane oxygenation and targeted temperature management in tricyclic antidepressant-induced cardiac arrest: A case report and literature review. Medicine (Baltimore) 2021; 100:e24980. [PMID: 33655968 PMCID: PMC7939188 DOI: 10.1097/md.0000000000024980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/11/2021] [Indexed: 11/25/2022] Open
Abstract
RATIONALE Cardiotoxicity is a common cause of death in tricyclic antidepressant (TCA) intoxication. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is effective in critically ill poisoned patients who do not respond to conventional therapies, and targeted temperature management (TTM) is associated with improved neurological outcomes and mortality in comatose out-of-hospital cardiac arrest survivors. However, few reports have documented cases of TCA intoxication that required intensive care, including VA-ECMO or TTM. PATIENT CONCERNS A 19-year-old Japanese man with a history of depression was brought to our hospital because he was in a comatose state with a generalized seizure. Before admission, he had taken an unknown amount of amitriptyline. DIAGNOSIS After intubation, the electrocardiogram (ECG) displayed a wide QRS complex tachycardia, and the patient suffered from cardiovascular instability despite intravenous bolus of sodium bicarbonate. At 200 minutes after ingestion, he experienced a TCA-induced cardiac arrest. INTERVENTIONS We initiated VA-ECMO 240 minutes after ingestion. The hemodynamic status stabilized, and the ECG abnormality improved gradually. In addition, we initiated targeted temperature management (TTM) with a target temperature of 34°C. OUTCOMES Twenty seven hours after starting the pump, the patient was weaned off the VA-ECMO. After completing the TTM, his mental status improved, and he was extubated on day 5. He was discharged on day 15 without neurological impairment, and the post-discharge course was uneventful. LESSONS First, VA-ECMO is effective in patients with TCA-induced cardiac arrest. Second, routine ECG screening during VA-ECMO support is useful for assessing the timing to wean off the VA-ECMO, as well as the degree of cardiotoxicity. Third, TTM is safe in comatose survivors of cardiac arrest caused by severe TCA intoxication.
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Rollason V, Lloret-Linares C, Lorenzini KI, Daali Y, Gex-Fabry M, Piguet V, Besson M, Samer C, Desmeules J. Evaluation of Phenotypic and Genotypic Variations of Drug Metabolising Enzymes and Transporters in Chronic Pain Patients Facing Adverse Drug Reactions or Non-Response to Analgesics: A Retrospective Study. J Pers Med 2020; 10:E198. [PMID: 33121061 PMCID: PMC7711785 DOI: 10.3390/jpm10040198] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 12/11/2022] Open
Abstract
This retrospective study evaluates the link between an adverse drug reaction (ADR) or a non-response to treatment and cytochromes P450 (CYP), P-glycoprotein (P-gp) or catechol-O-methyltransferase (COMT) activity in patients taking analgesic drugs for chronic pain. Patients referred to a pain center for an ADR or a non-response to an analgesic drug between January 2005 and November 2014 were included. The genotype and/or phenotype was obtained for assessment of the CYPs, P-gp or COMT activities. The relation between the event and the result of the genotype and/or phenotype was evaluated using a semi-quantitative scale. Our analysis included 243 individual genotypic and/or phenotypic explorations. Genotypes/phenotypes were mainly assessed because of an ADR (n = 145, 59.7%), and the majority of clinical situations were observed with prodrug opioids (n = 148, 60.9%). The probability of a link between an ADR or a non-response and the genotypic/phenotypic status of the patient was evaluated as intermediate to high in 40% and 28.2% of all cases, respectively. The drugs in which the probability of an association was the strongest were the prodrug opioids, with an intermediate to high link in 45.6% of the cases for occurrence of ADRs and 36.0% of the cases for non-response. This study shows that the genotypic and phenotypic approach is useful to understand ADRs or therapeutic resistance to a usual therapeutic dosage, and can be part of the evaluation of chronic pain patients.
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Affiliation(s)
- Victoria Rollason
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
| | - Célia Lloret-Linares
- Ramsay Générale de Santé, Hôpital Privé Pays de Savoie, Maladies Nutritionnelles et Métaboliques, 74000 Annemasse, France;
| | - Kuntheavy Ing Lorenzini
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
| | - Youssef Daali
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
| | - Marianne Gex-Fabry
- Division of Psychiatric Specialties, Department of Psychiatry and Mental Health, Geneva University Hospitals, 1226 Thônex, Switzerland;
| | - Valérie Piguet
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
| | - Marie Besson
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
| | - Caroline Samer
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
| | - Jules Desmeules
- Division of Clinical Pharmacology and Toxicology, Department of Anesthesiology, Pharmacology, Emergency Medicine and Intensive Care, Geneva University Hospitals, 1205 Geneva, Switzerland; (K.I.L.); (Y.D.); (V.P.); (M.B.); (C.S.); (J.D.)
- Faculty of Medicine, Geneva University, 1206 Geneva, Switzerland
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Mayumi K, Akazawa T, Kanazu T, Ohnishi S, Hasegawa H. Successful Prediction of Human Pharmacokinetics After Oral Administration by Optimized Physiologically Based Pharmacokinetics Approach and Permeation Assay Using Human Induced Pluripotent Stem Cell–Derived Intestinal Epithelial Cells. J Pharm Sci 2020; 109:1605-1614. [DOI: 10.1016/j.xphs.2019.12.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 12/29/2022]
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Tylutki Z, Polak S. A four-compartment PBPK heart model accounting for cardiac metabolism - model development and application. Sci Rep 2017; 7:39494. [PMID: 28051093 PMCID: PMC5209692 DOI: 10.1038/srep39494] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/21/2016] [Indexed: 12/20/2022] Open
Abstract
In the field of cardiac drug efficacy and safety assessment, information on drug concentration in heart tissue is desirable. Because measuring drug concentrations in human cardiac tissue is challenging in healthy volunteers, mathematical models are used to cope with such limitations. With a goal of predicting drug concentration in cardiac tissue, we have developed a whole-body PBPK model consisting of seventeen perfusion-limited compartments. The proposed PBPK heart model consisted of four compartments: the epicardium, midmyocardium, endocardium, and pericardial fluid, and accounted for cardiac metabolism using CYP450. The model was written in R. The plasma:tissues partition coefficients (Kp) were calculated in Simcyp Simulator. The model was fitted to the concentrations of amitriptyline in plasma and the heart. The estimated parameters were as follows: 0.80 for the absorption rate [h-1], 52.6 for Kprest, 0.01 for the blood flow through the pericardial fluid [L/h], and 0.78 for the P-parameter describing the diffusion between the pericardial fluid and epicardium [L/h]. The total cardiac clearance of amitriptyline was calculated as 0.316 L/h. Although the model needs further improvement, the results support its feasibility, and it is a first attempt to provide an active drug concentration in various locations within heart tissue using a PBPK approach.
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Affiliation(s)
- Zofia Tylutki
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Department of Social Pharmacy, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Str., 30-688 Cracow, Poland
| | - Sebastian Polak
- Unit of Pharmacoepidemiology and Pharmacoeconomics, Department of Social Pharmacy, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Str., 30-688 Cracow, Poland
- Simcyp (a Certara Company) Limited, Blades Enterprise Centre, John Street, Sheffield S2 4SU, UK
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Youssef AS, Parkman HP, Nagar S. Drug-drug interactions in pharmacologic management of gastroparesis. Neurogastroenterol Motil 2015; 27:1528-41. [PMID: 26059917 DOI: 10.1111/nmo.12614] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 05/13/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND Gastroparesis is a disorder characterized by delayed gastric emptying due to chronic abnormal gastric motility. The treatment of the disease often entails the co-administration of several classes of pharmacological agents. These agents may be metabolized via the same pathway. Inhibition or induction of a shared metabolic pathway leads to change in the systemic levels of prescribed drugs, possibly leading to undesired clinical outcomes. PURPOSE This review discusses different pharmacological treatment for gastroparesis patients and describes the potential for drug-drug interactions (DDIs) in some of the combinations that are currently used. Prokinetic agents such as metoclopramide and domperidone are the cornerstone in treatment of gastroparesis. Antiemetic agents such as promethazine and ondansetron are frequently administered to gastroparesis patients to reduce nausea and vomiting. Gastroparesis is prevalent in diabetic patients and therefore antidiabetic agents are also prescribed. Many of these co-administered drugs are metabolized via common drug metabolizing enzymes and this can trigger potential DDIs. The scientific literature was reviewed from the years 1975-2014 for original research articles and reviews that evaluated DDIs in gastroparesis. Many commonly prescribed combinations were predicted to cause potential DDIs in gastroparesis patients. This review will help inform about potential hazardous combinations. This information will hopefully lead to less adverse effects and more successful gastroparesis management.
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Affiliation(s)
- A S Youssef
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - H P Parkman
- Gastroenterology Section, Temple University School of Medicine, Philadelphia, PA, USA
| | - S Nagar
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
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Chan LN, Anderson GD. Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol). Clin Pharmacokinet 2015; 53:1115-36. [PMID: 25267448 DOI: 10.1007/s40262-014-0190-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.
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Affiliation(s)
- Lingtak-Neander Chan
- Department of Pharmacy, University of Washington, Box 357630, Seattle, WA, 98195, USA
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Wójcikowski J, Basińska A, Boksa J, Daniel WA. The influence of amitriptyline and carbamazepine on levomepromazine metabolism in human liver: An in vitro study. Pharmacol Rep 2014; 66:1122-6. [DOI: 10.1016/j.pharep.2014.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 01/17/2023]
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A cocktail approach for assessing the in vitro activity of human cytochrome P450s: An overview of current methodologies. J Pharm Biomed Anal 2014; 101:221-37. [DOI: 10.1016/j.jpba.2014.03.018] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 03/13/2014] [Indexed: 01/27/2023]
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Kuo HW, Liu SC, Tsou HH, Liu SW, Lin KM, Lu SC, Hsiao MC, Hsiao CF, Liu CY, Chen CH, Lu ML, Shen WW, Tang HS, Liu SI, Chang LH, Wu HY, Chang YS, Yeh TK, Chen AC, Liu YL. CYP1A2 genetic polymorphisms are associated with early antidepressant escitalopram metabolism and adverse reactions. Pharmacogenomics 2014; 14:1191-201. [PMID: 23859573 DOI: 10.2217/pgs.13.105] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIM The liver CYP1A2 enzyme may metabolize antidepressant escitalopram (S-CIT) to S-desmethylcitalopram (S-DCIT) and S-didesmethylcitalopram (S-DDCIT). This study tested whether genetic polymorphisms in the CYP1A2 gene are associated with the treatment responses to S-CIT. MATERIALS & METHODS Ten SNPs in CYP1A2 were selected and genotyped in 158 patients under S-CIT treatment. The serum levels of S-CIT and its metabolites were measured by HPLC. RESULTS CYP1A2 SNPs rs2069521, rs2069526, rs4646425 and rs4646427 are significantly associated with the metabolic ratios of S-DDCIT/S-DCIT (p = 0.002, 0.018, 0.008 and 0.004, respectively) at week 2 of treatment. Carriers of the allele types associated with higher S-DDCIT/S-DCIT ratios had more severe side effects. CONCLUSION These results suggest that genetic variants in CYP1A2 may be indicators for S-CIT metabolism and that the fast metabolizers may experience more severe adverse reactions in the early stages of S-CIT treatment. Original submitted 27 December 2012; Revision submitted 15 May 2013.
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Affiliation(s)
- Hsiang-Wei Kuo
- Center for Neuropsychiatric Research, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 350, Taiwan
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Interaction of valproic acid and amitriptyline: analysis of therapeutic drug monitoring data under naturalistic conditions. J Clin Psychopharmacol 2013; 33:561-4. [PMID: 23775047 DOI: 10.1097/jcp.0b013e3182905d42] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Amitriptyline (AMI) and valproic acid (VPA) are common psychotropic drugs which are frequently used in psychiatry and also administered in neurology or anesthesia in the absence of a psychiatric indication. On the basis of the case of a 73-year-old man with therapy-resistant major depressive episode who experienced anticholinergic delirium after adding VPA to AMI, we retrospectively analyzed therapeutic drug monitoring data of the years 2008 to 2010. We assessed cases receiving a combination of AMI and VPA, and obtained a control sample of AMI patients without VPA which were matched for sex, age, daily dose, and comedication. Both samples were compared regarding the serum levels of AMI and nortriptyline (NOR) as well as the ratio of NOR and AMI with the Mann-Whitney U test. The combination of AMI and VPA led to a remarkable increase of AMI and NOR serum levels. When comparing 33 patients who received comedication with VPA versus 33 matched controls, the total concentration by combining mean AMI and NOR serum levels (237.1 [119.9] vs 126.4 [52.8] ng/mL) and NOR/AMI ratio (1.300 [0.905] vs 0.865 [0.455]) was significantly higher. Both AMI and VPA are widely prescribed drugs. A combination of both is common for psychiatric or neurologic patients. A cautious dosing of AMI with VPA comedication is advisable, and therapeutic drug monitoring should be performed because this combination may lead to a remarkable increase of AMI and NOR serum levels.
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Samartzis L, Savvari P, Kontogiannis S, Dimopoulos S. Linezolid is associated with serotonin syndrome in a patient receiving amitriptyline, and fentanyl: a case report and review of the literature. Case Rep Psychiatry 2013; 2013:617251. [PMID: 23533900 PMCID: PMC3603624 DOI: 10.1155/2013/617251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/06/2013] [Indexed: 02/07/2023] Open
Abstract
We report a unique case of an adverse interaction between the oxazolidinone antibiotic linezolid, the tricyclic antidepressant amitriptyline and the opioid analgesic fentanyl in a 68-year-old woman with advanced ischemic peripheral arterial disease and sepsis, under empirical antibiotic treatment. We also summarize the current relevant literature as identified via PubMed, EMBASE, and PsycINFO as well as reference sections of selected articles.
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Affiliation(s)
- Lampros Samartzis
- 1Department of Psychiatry, Mental Health Services, Athalassa Psychiatric Hospital, 1452 Nicosia, Cyprus
| | - Paraskevi Savvari
- 2Department of Clinical Therapeutics, National and Kapodistrian University of Athens, Alexandra Hospital, 80 Vas. Sofias Avenue, 11528 Athens, Greece
| | - Sofoklis Kontogiannis
- 2Department of Clinical Therapeutics, National and Kapodistrian University of Athens, Alexandra Hospital, 80 Vas. Sofias Avenue, 11528 Athens, Greece
| | - Stavros Dimopoulos
- 2Department of Clinical Therapeutics, National and Kapodistrian University of Athens, Alexandra Hospital, 80 Vas. Sofias Avenue, 11528 Athens, Greece
- *Stavros Dimopoulos:
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Wang J, Hirai H, Kawagishi H. Biotransformation of acetamiprid by the white-rot fungus Phanerochaete sordida YK-624. Appl Microbiol Biotechnol 2011; 93:831-5. [PMID: 21713509 DOI: 10.1007/s00253-011-3435-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 06/05/2011] [Accepted: 06/06/2011] [Indexed: 11/28/2022]
Abstract
Acetamiprid (ACE) belongs to the neonicotinoid class of systemic broad-spectrum insecticides, which are the most highly effective and largest-selling insecticides worldwide for crop protection. As neonicotinoid insecticides persist in crops, biotransformation of these insecticides represents a promising approach for improving the safety of foods. Here, the elimination of ACE from a liquid medium by the white-rot fungus Phanerochaete sordida YK-624 was examined. Under ligninolytic and non-ligninolytic conditions, 45% and 30% of ACE were eliminated, respectively, after 15 days of incubation. High-resolution electrospray ionization mass spectra and nuclear magnetic resonance analyses of a metabolite identified in the culture supernatant suggested that ACE was N-demethylated to (E)-N (1)-[(6-chloro-3-pyridyl)-methyl]-N (2)-cyano-acetamidine, which has a much lower toxicity than ACE. In addition, we investigated the effect of the cytochrome P450 inhibitor piperonyl butoxide (PB) on the elimination of ACE. The elimination rate of ACE by P. sordida YK-624 was markedly reduced by the addition of either 0.01 or 0.1 mM PB to the culture medium. These results suggest that cytochrome P450 plays an important role in the N-demethylation of ACE by P. sordida YK-624.
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Affiliation(s)
- Jianqiao Wang
- Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
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Tam TW, Liu R, Arnason JT, Krantis A, Staines WA, Haddad PS, Foster BC. Cree antidiabetic plant extracts display mechanism-based inactivation of CYP3A4. Can J Physiol Pharmacol 2011; 89:13-23. [DOI: 10.1139/y10-104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Seventeen Cree antidiabetic medicinal plants were studied to determine their potential to inhibit cytochrome P450 3A4 (CYP3A4) through mechanism-based inactivation (MBI). The ethanolic extracts of the medicinal plants were studied for their inhibition of CYP3A4 using the substrates testosterone and dibenzylfluorescein (DBF) in high pressure liquid chromatography (HPLC) and microtiter fluorometric assays, respectively. Using testosterone as a substrate, extracts of Alnus incana , Sarracenia purpurea , and Lycopodium clavatum were identified as potent CYP3A4 MBIs, while those from Abies balsamea , Picea mariana , Pinus banksiana , Rhododendron tomentosum , Kalmia angustifolia , and Picea glauca were identified as less potent inactivators. Not unexpectedly, the other substrate, DBF, showed a different profile of inhibition. Only A. balsamea was identified as a CYP3A4 MBI using DBF. Abies balsamea displayed both NADPH- and time-dependence of CYP3A4 inhibition using both substrates. Overall, several of the medicinal plants may markedly deplete CYP3A4 through MBI and, consequently, decrease the metabolism of CYP3A4 substrates including numerous medications used by diabetics.
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Affiliation(s)
- Teresa W. Tam
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Rui Liu
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - John T. Arnason
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Anthony Krantis
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - William A. Staines
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Pierre S. Haddad
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
| | - Brian C. Foster
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Research in Biopharmaceuticals and Biotechnology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Pharmacology, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Therapeutic Products Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada
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Cascorbi I. Safe and effective medicines for all: is personalized medicine the answer? Expert Rev Clin Pharmacol 2010; 3:627-37. [PMID: 22111745 DOI: 10.1586/ecp.10.36] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
An improvement in drug treatment and clinical outcome is one of the major challenges in clinical medicine. The development of evidence-based standards of care has led to a significant improvement, but, by definition, strictly standardized cohorts in clinical trials have to ignore individual differences. Personalized medicine is defined as the application of genomic and molecular data to better target the delivery of healthcare, facilitate the discovery and clinical testing of new products, and help determine a person's predisposition to a particular disease or condition. After the deciphering of the human genome, however, the high expectations in individualized medicine were not always fulfilled. However, personalized medicine has become indispensable in the treatment of malignant diseases and there is increasing evidence for its benefit in other areas. This article outlines the impact of pharmacogenetics and pharmacogenomics, especially with regard to personalized medicine, in major medical indications and reflects the obstacles and chances taken in current daily practice.
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Affiliation(s)
- Ingolf Cascorbi
- Institute for Experimental and Clinical Pharmacology, University Hospital Schleswig-Holstein, Arnold-Heller-Str. 3, Bldg 30, D-24105 Kiel, Germany.
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19
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Pharmacogenetics of anxiolytic drugs. J Neural Transm (Vienna) 2009; 116:667-77. [DOI: 10.1007/s00702-009-0229-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 04/14/2009] [Indexed: 12/15/2022]
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Krystal AD. A compendium of placebo-controlled trials of the risks/benefits of pharmacological treatments for insomnia: the empirical basis for U.S. clinical practice. Sleep Med Rev 2009; 13:265-74. [PMID: 19153052 DOI: 10.1016/j.smrv.2008.08.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For many years practitioners have had limited data from double-blind, placebo-controlled studies to guide the types of decision-making needed to optimally manage patients with insomnia in clinical practice. However, in recent years there has been a great increase in insomnia research studies that address issues of clinical importance. This body of work represents an increasingly useful empirical basis for making clinical practice decisions. The purpose of this article is to compile the body of work on the pharmacological management of insomnia to make it available in as accessible form as possible for optimal application in clinical practice with the hopes that doing so will decrease the gap separating the available research and the clinical management of insomnia and, thereby, improve the care of the many individuals who suffer from this condition. The review of studies consists of the following sections: 1) basic pharmacology; 2) double-blind, placebo-controlled trials in adults with primary insomnia; 3) double-blind, placebo-controlled trials in elderly patients with primary insomnia; 4) adverse effects reported in placebo-controlled trials in elderly primary insomnia patients; 5) double-blind, placebo-controlled trials in adults and the elderly as a function of treatment duration; 6) double-blind, placebo-controlled trials of the treatment of comorbid insomnia. Issues related to the application of these data to clinical practice are discussed in the text.
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Affiliation(s)
- Andrew D Krystal
- Insomnia and Sleep Research Laboratory, Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Duke South Hospital, Trent Drive, Durham, NC 27710, USA.
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21
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Brandes LJ. Hormetic Effects of Hormones, Antihormones, and Antidepressants on Cancer Cell Growth in Culture: In Vivo Correlates. Crit Rev Toxicol 2008; 35:587-92. [PMID: 16422394 DOI: 10.1080/10408440500246801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Evidence is presented that the ability of hormones and antihormones to cause biphasic (hormetic) proliferative responses in cancer cells in vitro correlates with a similar effect of these substances in humans with cancer. Certain antidepressants also produce biphasic growth responses of cancer cells in vitro and stimulate cancer growth in rodents, correlating with an increased risk of breast and other cancers in some, but not all, epidemiological studies assessing early and/or late cancer incidence in patients on antidepressant drugs. The observation that certain drugs with biphasic effects on cancer cell growth in vitro may also produce an "up-down" effect on cancer growth in humans supports Calabrese's suggestion that the concept of the hormetic dose response must be taken seriously by toxicologists and regulators.
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Zanger UM, Turpeinen M, Klein K, Schwab M. Functional pharmacogenetics/genomics of human cytochromes P450 involved in drug biotransformation. Anal Bioanal Chem 2008; 392:1093-108. [PMID: 18695978 DOI: 10.1007/s00216-008-2291-6] [Citation(s) in RCA: 541] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Accepted: 07/09/2008] [Indexed: 12/17/2022]
Abstract
We investigated the elimination routes for the 200 drugs that are sold most often by prescription count in the United States. The majority (78%) of the hepatically cleared drugs were found to be subject to oxidative metabolism via cytochromes P450 of the families 1, 2 and 3, with major contributions from CYP3A4/5 (37% of drugs) followed by CYP2C9 (17%), CYP2D6 (15%), CYP2C19 (10%), CYP1A2 (9%), CYP2C8 (6%), and CYP2B6 (4%). Clinically well-established polymorphic CYPs (i.e., CYP2C9, CYP2C19, and CYP2D6) were involved in the metabolism of approximately half of those drugs, including (in particular) NSAIDs metabolized mainly by CYP2C9, proton-pump inhibitors metabolized by CYP2C19, and beta blockers and several antipsychotics and antidepressants metabolized by CYP2D6. In this review, we provide an up-to-date summary of the functional polymorphisms and aspects of the functional genomics of the major human drug-metabolizing cytochrome P450s, as well as their clinical significance.
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Affiliation(s)
- Ulrich M Zanger
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Auerbachstr. 112, 70376, Stuttgart, Germany.
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23
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Sykes MJ, McKinnon RA, Miners JO. Prediction of Metabolism by Cytochrome P450 2C9: Alignment and Docking Studies of a Validated Database of Substrates. J Med Chem 2008; 51:780-91. [DOI: 10.1021/jm7009793] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Skaggs SM, Foti RS, Fisher MB. A streamlined method to predict hepatic clearance using human liver microsomes in the presence of human plasma. J Pharmacol Toxicol Methods 2005; 53:284-90. [PMID: 16300971 DOI: 10.1016/j.vascn.2005.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Accepted: 10/14/2005] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Human liver microsomal incubations are often used to predict the metabolic lability of new chemical entities. The clearance values are scaled-up from in vitro data and mathematically corrected for plasma protein binding, or in some cases the free fraction ratio of plasma to microsomes, using well-established scaling methods such as the well-stirred model. This can be time consuming for multiple compounds since it requires separate experiments to determine in vitro lability, and free fraction. METHODS We attempted to streamline clearance predictions by combining experiments into one. Firstly, we combined the free fraction experiments into one free fraction ratio by measuring the partitioning of compound between plasma and microsomes, and by applying this experimental ratio to clearance predictions found that it performed at least as well as free fractions determined separately. We also incubated compounds with plasma added to the incubation mixture and compared the predicted clearances to values determined using traditional mathematical protein binding corrections. RESULTS Consistently, incubations with added plasma resulted in CL predictions closer to literature values than incubations only mathematically corrected for protein binding. For example, incorporating plasma into a ketamine incubation resulted in a CL value of 15.1 mL/min/kg, compared with a value of 10.2 using mathematical binding corrections. The literature value is 16.4 mL/min/kg. DISCUSSION This work characterizes this new method and compares it to the traditional microsomal incubation method using several literature compounds, and suggests that streamlining the methods may generate quality data faster and with less resource investment.
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Affiliation(s)
- Sara M Skaggs
- Pfizer Global Research and Development, Pharmacokinetics, Dynamics, and Metabolism Pfizer, Inc. Groton, CT 06340, USA
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Daniel WA. The influence of long-term treatment with psychotropic drugs on cytochrome P450: the involvement of different mechanisms. Expert Opin Drug Metab Toxicol 2005; 1:203-17. [PMID: 16922637 DOI: 10.1517/17425255.1.2.203] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This paper emphasises that besides the direct action of psychotropic drugs on cytochrome P450 (CYP) (i.e., the binding of the parent drug to the enzyme) indirect mechanisms of CYP-psychotropic interactions, namely the formation of CYP-reactive metabolite complexes and their influence on enzyme regulation, are also very important. The described interactions that are time-, drug- and CYP isoform-dependent may overlap during long-term treatment. The final result of the overlapping depends on the dosage and time interval after the last administration of a drug, which determines the concentration of the parent drug and its metabolites in the environment of the enzyme. These interactions may occur not only in the liver, but also in the brain, and may change the activity of CYP towards the metabolism of drugs, sex steroids, neurosteroids and amine neurotransmitters. The role of the CNS in the regulation of CYP by psychotropics and the significance of CYP-psychotropic interactions for pharmacological and clinical profiling of these drugs is discussed. In addition, different experimental approaches for studying CNS-acting drugs are compared.
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Affiliation(s)
- Wladyslawa Anna Daniel
- Polish Academy of Sciences, Institute of Pharmacology, Smeetna 12, 31-343 Kraków, Poland.
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Yu AM, Idle JR, Gonzalez FJ. Polymorphic cytochrome P450 2D6: humanized mouse model and endogenous substrates. Drug Metab Rev 2004; 36:243-77. [PMID: 15237854 DOI: 10.1081/dmr-120034000] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cytochrome P450 2D6 (CYP2D6) is the first well-characterized polymorphic phase I drug-metabolizing enzyme, and more than 80 allelic variants have been identified for the CYP2D6 gene, located on human chromosome 22q13.1. Human debrisoquine and sparteine metabolism is subdivided into two principal phenotypes--extensive metabolizer and poor metabolizer--that arise from variant CYP2D6 genotypes. It has been estimated that CYP2D6 is involved in the metabolism and disposition of more than 20% of prescribed drugs, and most of them act in the central nervous system or on the heart. These drug substrates are characterized as organic bases containing one nitrogen atom with a distance about 5, 7, or 10 A from the oxidation site. Aspartic acid 301 and glutamic acid 216 were determined as the key acidic residues for substrate-enzyme binding through electrostatic interactions. CYP2D6 transgenic mice, generated using a lambda phage clone containing the complete wild-type CYP2D6 gene, exhibits enhanced metabolism and disposition of debrisoquine. This transgenic mouse line and its wild-type control are models for human extensive metabolizers and poor metabolizers, respectively, and would have broad application in the study of CYP2D6 polymorphism in drug discovery and development, and in clinical practice toward individualized drug therapy. Endogenous 5-methoxyindole- thylamines derived from 5-hydroxytryptamine were identified as high-affinity substrates of CYP2D6 that catalyzes their O-demethylations with high enzymatic capacity and specificity. Thus, polymorphic CYP2D6 may play an important role in the interconversions of these psychoactive tryptamines, including a crucial step in a serotonin-melatonin cycle.
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Affiliation(s)
- Ai-Ming Yu
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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27
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Flanagan JU, Maréchal JD, Ward R, Kemp CA, McLaughlin LA, Sutcliffe MJ, Roberts GCK, Paine MJI, Wolf CR. Phe120 contributes to the regiospecificity of cytochrome P450 2D6: mutation leads to the formation of a novel dextromethorphan metabolite. Biochem J 2004; 380:353-60. [PMID: 14992686 PMCID: PMC1224184 DOI: 10.1042/bj20040062] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 02/13/2004] [Accepted: 03/01/2004] [Indexed: 11/17/2022]
Abstract
Although the residues that determine the preference of CYP2D6 (cytochrome P450 2D6) for compounds containing a basic nitrogen are well characterized, the contribution of other active site residues to substrate binding and orientation is less well understood. Our structural model of CYP2D6 identifies the aromatic residue Phe120 as a likely major feature of the active site. To examine the role of Phe120, mutants of CYP2D6 in which this residue has been substituted by alanine, leucine, tyrosine, serine, histidine, tryptophan or methionine residues have been prepared in bacterial membranes co-expressing human cytochrome NADPH cytochrome P450 oxidoreductase. The mutants have been characterized using the prototypical bufuralol 1' hydroxylase and dextromethorphan O- and N-demethylase activities of CYP2D6. Larger effects on K(m) values are observed for dextromethorphan O-demethylation than for bufuralol 1' hydroxylation, indicating that the Phe120 side chain is more important in dextromethorphan than in bufuralol binding. A role for this side chain in determining the regiospecificity of substrate oxidation was indicated by changes in the relative rates of O- and N-demethylation of dextromethorphan and, notably, by the formation of 7-hydroxy dextromethrophan, a novel dextromethorphan metabolite, in mutants in which it had been substituted. Computational studies of dextromethorphan binding to the active site of the Phe120-->Ala mutant were carried out to throw light on the way in which the removal of this side chain leads to different modes of ligand binding.
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Affiliation(s)
- Jack U Flanagan
- Biomedical Research Centre, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK
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Gervasini G, Carrillo JA, Benitez J. Potential role of cerebral cytochrome P450 in clinical pharmacokinetics: modulation by endogenous compounds. Clin Pharmacokinet 2004; 43:693-706. [PMID: 15301574 DOI: 10.2165/00003088-200443110-00001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cytochrome P450 (CYP) enzymes catalyse phase I metabolic reactions of psychotropic drugs. The main isoenzymes responsible for this biotransformation are CYP1A2, CYP2D6, CYP3A and those of the subfamily CYP2C. Although these enzymes are present in the human brain, their specific role in this tissue remains unclear. However, because CYP enzymatic activities have been reported in the human brain and because brain microsomes have been shown to metabolise the same probe substrates used to assess specific hepatic CYP activities and substrates of known hepatic CYPs, local drug metabolism is believed to be likely. There are also indications that CYP2D6 is involved in the metabolism of endogenous substrates in the brain. This, along with the fact that several neurotransmitters modulate CYP enzyme activities in human liver microsomes, indicates that CYP enzymes present in brain could be under various regulatory mechanisms and that those mechanisms could influence drug pharmacokinetics and, hence, drug response. In this paper we review the presence of CYP1A2, CYP2C9, CYP2D6 and CYP3A in brain, as well as the possible existence of local brain metabolism, and discuss the putative implications of endogenous modulation of these isoenzymes by neurotransmitters.
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Affiliation(s)
- Guillermo Gervasini
- Department of Pharmacology and Psychiatry, Medical School, University of Extremadura, Badajoz, Spain
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Vartanian F. Neurobiological differences on populational level. Prog Neuropsychopharmacol Biol Psychiatry 2004; 28:909-12. [PMID: 15363613 DOI: 10.1016/j.pnpbp.2004.05.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2004] [Indexed: 10/26/2022]
Abstract
At present, 13% of world population are suffering from neuropsychiatric disorders. Prevention and treatment of these pathological conditions are very important. New research strategies are needed for the creation of effective methods for controlling of neuropsychiatric disorders. International collaborative research projects within WHO's activities in psychopharmacology and biological psychiatry with the participation of 12 countries representing different world regions have been organized and successfully finalized. The author discusses some of these in the Festschrift for Dr. Corneille Radouco-Thomas.
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Affiliation(s)
- Felix Vartanian
- Ministry of Health, Russian Academy of Advanced Medical Studies, 123995, Moscow, Barrikadnaya str. 2, Russia.
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Abstract
Interindividual differences in the pharmacokinetics of a number of drugs are often due to hereditary polymorphisms of drug-metabolizing enzymes. Most important is cytochrome p4502D6 (CYP2D6), also known as debrisoquine/sparteine hydroxylase. It catalyzes hydroxylation or demethylation of more than 20% of drugs metabolized in the human liver, such as neuroleptics, antidepressants, some beta-blockers and many others like codeine. About 7%-10% of Caucasians lack any CYP2D6 activity due to deletions and frame-shift or splice-site mutations of the gene. About 1%-3% of Middle-Europeans, but up to 29% of Ethiopians display gene duplications, leading to elevated so-called ultrarapid metabolization rates. Meanwhile there is now a much better understanding of the genetic background of poor, intermediate, extensive and ultrarapid metabolizers, enabling a more precise DNA genotyping-based prediction of plasma levels. Since there is evidence that deteriorated drug elimination partly accounts for drug side-effects, CYP2D6 genotyping could contribute to an individualized and therefore optimized drug therapy.
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Affiliation(s)
- I Cascorbi
- Institute of Pharmacology, Ernst Moritz Arndt University Greifswald, Germany.
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Abstract
This review focuses on the toxicological interactions between alcohol (ethanol) and psychiatric drugs (antidepressants and antipsychotics), including those leading to fatal poisoning. Acute or chronic ingestion of alcohol when combined with psychiatric drugs may lead to several clinically significant toxicological interactions. The metabolism of these drugs is generally but not always delayed by acute alcohol ingestion. Drugs undergoing metabolism may also show increased metabolic clearance with chronic alcohol ingestion. Therefore, the net effect may be influenced by internal (e.g. disease, age, gender), external (e.g. environment, diet) and pharmacokinetic (e.g. dose, timing of ingestion, gastrointestinal absorption, distribution and elimination) factors. Cases of fatal poisoning involving coadministration of psychiatric drugs, alcohol and other drugs prompted this review.
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Affiliation(s)
- E Tanaka
- Department of Forensic Medicine, Institute of Community Medicine, University of Tsukuba, Ibaraki-ken, Japan.
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Abstract
BACKGROUND Varicella-zoster virus causes chickenpox and can reemerge later in life to cause herpes zoster or shingles. One of the most common and disabling complications of herpes zoster is postherpetic neuralgia (PHN). OBJECTIVES This article reviews the current primary literature about the efficacy and tolerability of gabapentin for the treatment of PHN. Gabapentin pharmacokinetics and drug interactions are also reviewed. METHODS A literature search in the English language was conducted using OVID Web, which contained the following databases: MEDLINE (1966-present), EMBASE (1980-2002), Current Contents/Clinical Medicine (1999-2002), Cochrane Controlled Trials Register (1898-present), Cochrane Database of Systemic Reviews (fourth quarter, 2002), and International Pharmaceutical Abstracts (1970-2002). Search terms used were postherpetic neuralgia; zoster; gabapentin; neuropathic pain; pain; pharmacoeconomic; cost; controlled clinical trial; randomized, controlled trial; postherpetic neuralgia and gabapentin; gabapentin and pain; treatment and postherpetic neuralgia; gabapentin and age; gabapentin and gender; gabapentin and ethnicity; and gabapentin and pharmacokinetics. RESULTS Gabapentin displays nonlinear absorption kinetics, is minimally protein bound (< 3%), has a high mean (SD) volume of distribution (50.4 [8.0] L), and is excreted via the kidneys as unchanged drug. Two randomized, placebo-controlled, parallel-group, multicenter clinical trials demonstrated the effectiveness of gabapentin at doses of up to 3600 mg/d to significantly reduce pain (P < 0.01 and P < 0.001), improve sleep (P < 0.01), and improve some parameters on the Short Form-McGill Pain Questionnaire (P < 0.05). Dizziness and somnolence were the most common side effects leading to withdrawal from the trials. The recommended dosage in adults is 300 mg at bedtime on day 1,300 mg BID on day 2, and 300 mg TID on day 3, titrating up as needed to 2400 to 3600 mg/d. To reduce adverse events in patients with renal impairment, the dose should be adjusted based on the patient's creatinine clearance. CONCLUSIONS Gabapentin appears to be effective and well tolerated for the short-term treatment of PHN. However, future controlled studies are needed to determine whether the effectiveness of gabapentin for PHN is maintained for > 2 months, to establish the optimal dose of gabapentin for PHN, and to compare the efficacy of gabapentin with that of other pharmacologic agents used for the treatment of PHN.
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Affiliation(s)
- Devada Singh
- Pharmacy Practice, Nova Southeastern University College of Pharmacy-Davie Campus, Fort Lauderdale, Florida 33328-2018, USA.
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Sennef C, Timmer CJ, Sitsen JMA. Mirtazapine in combination with amitriptyline: a drug-drug interaction study in healthy subjects. Hum Psychopharmacol 2003; 18:91-101. [PMID: 12590402 DOI: 10.1002/hup.441] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To assess the steady-state pharmacokinetics of mirtazapine (30 mg/day orally) and amitriptyline (75 mg/day orally) during combined administration compared with that of either drug administered alone. To evaluate the tolerability and effects on psychometric tests of acute and subchronic administration of both drugs combined and alone. METHODS In a single-blind, three-way cross-over study, 24 (12 male and 12 female) healthy subjects were randomly assigned to six different sequences of three 9-day treatments, i.e. racemic mirtazapine (30 mg/day), amitriptyline (75 mg/day) or the combination of these drugs. To control for acute pharmacodynamic assessments, during the first treatment period, a placebo group (n = 8; 4 females and 4 males) was added. Serial blood samples were drawn for plasma level measurements that were subsequently subjected to pharmacokinetic analysis. Psychometric tests assessed attentional performance, and a computer-assisted telephone questionnaire assessed self-ratings of drowsiness/alertness and sleep quality. RESULTS Amitriptyline increased the C(max) of mirtazapine (+ 36%, p < 0.05) in male subjects only. Mirtazapine altered the C(max) of amitriptyline in both male (+ 23%, p < 0.05) and female (- 23%, p < 0.05) subjects. No changes were observed for other pharmacokinetic parameters. Metabolite parameters were not affected. Changes in parent compound levels mainly resulted from effects on absorption. The psychometric test results did not reveal significant changes between combined and single drug treatments. The telephone registrations of VAMRS and LSEQ did not show clinically relevant differences between the active treatments. CONCLUSION Combined administration of mirtazapine (30 mg/day) and amitriptyline (75 mg/day) alters the pharmacokinetics of either compound to a minor extent. Adding one drug to the other and substituting one drug by the other had no major effects on tolerability. Nevertheless, caution is warranted when combining amitriptyline and mirtazapine.
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Affiliation(s)
- C Sennef
- NV Organon, PO Box 20, 5340 BH Oss, The Netherlands
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Paine MJI, McLaughlin LA, Flanagan JU, Kemp CA, Sutcliffe MJ, Roberts GCK, Wolf CR. Residues glutamate 216 and aspartate 301 are key determinants of substrate specificity and product regioselectivity in cytochrome P450 2D6. J Biol Chem 2003; 278:4021-7. [PMID: 12446689 DOI: 10.1074/jbc.m209519200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 2D6 (CYP2D6) metabolizes a wide range of therapeutic drugs. CYP2D6 substrates typically contain a basic nitrogen atom, and the active-site residue Asp-301 has been implicated in substrate recognition through electrostatic interactions. Our recent computational models point to a predominantly structural role for Asp-301 in loop positioning (Kirton, S. B., Kemp, C. A., Tomkinson, N. P., St.-Gallay, S., and Sutcliffe, M. J. (2002) Proteins 49, 216-231) and suggest a second acidic residue, Glu-216, as a key determinant in the binding of basic substrates. We have evaluated the role of Glu-216 in substrate recognition, along with Asp-301, by site-directed mutagenesis. Reversal of the Glu-216 charge to Lys or substitution with neutral residues (Gln, Phe, or Leu) greatly decreased the affinity (K(m) values increased 10-100-fold) for the classical basic nitrogen-containing substrates bufuralol and dextromethorphan. Altered binding was also manifested in significant differences in regiospecificity with respect to dextromethorphan, producing enzymes with no preference for N-demethylation versus O-demethylation (E216K and E216F). Neutralization of Asp-301 to Gln and Asn had similarly profound effects on substrate binding and regioselectivity. Intriguingly, removal of the negative charge from either 216 or 301 produced enzymes (E216A, E216K, and D301Q) with elevated levels (50-75-fold) of catalytic activity toward diclofenac, a carboxylate-containing CYP2C9 substrate that lacks a basic nitrogen atom. Activity was increased still further (>1000-fold) upon neutralization of both residues (E216Q/D301Q). The kinetic parameters for diclofenac (K(m) 108 microm, k(cat) 5 min(-1)) along with nifedipine (K(m) 28 microm, k(cat) 2 min(-1)) and tolbutamide (K(m) 315 microm, k(cat) 1 min(-1)), which are not normally substrates for CYP2D6, were within an order of magnitude of those observed with CYP3A4 or CYP2C9. Neutralizing both Glu-216 and Asp-301 thus effectively alters substrate recognition illustrating the central role of the negative charges provided by both residues in defining the specificity of CYP2D6 toward substrates containing a basic nitrogen.
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Affiliation(s)
- Mark J I Paine
- Biomedical Research Centre, University of Dundee, Ninewells Hospital and Medical School, United Kingdom
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Photophysical and photochemical properties of amitriptyline and nortriptyline hydrochloride: a 266 nm nanosecond laser flash and theoretical study. J Photochem Photobiol A Chem 2003. [DOI: 10.1016/s1010-6030(02)00353-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shimoda K, Someya T, Yokono A, Morita S, Hirokane G, Takahashi S, Okawa M. The impact of CYP2C19 and CYP2D6 genotypes on metabolism of amitriptyline in Japanese psychiatric patients. J Clin Psychopharmacol 2002; 22:371-8. [PMID: 12172336 DOI: 10.1097/00004714-200208000-00007] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We investigated the effect of the CYP2C19 and CYP2D6 genotypes on the metabolism of amitriptyline (AT) in Japanese psychiatric patients. Steady-state concentrations of AT and its metabolites (nortriptyline [NT], trans-10-hydroxy-nortriptyline [EHNT], cis-10-hydroxy-nortriptyline [ZHNT], trans-10-hydroxy-amitriptyline [EHAT], and cis-10-hydroxy-amitriptyline [ZHAT]) in 50 patients were determined by high-performance liquid chromatography. Significantly higher plasma concentrations of AT corrected for dose and body weight in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 were observed (no mutated alleles vs. two mutated alleles: 36.0 +/- 18.2 vs. 64.0 +/- 25.2 ng/mL/mg/kg, p = 0.025). A significantly higher AT/NT ratio was seen in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 (no mutated alleles vs. two mutated alleles: 1.27 +/- 0.59 vs. 3.40 +/- 1.02, p = 0.001). A trend for higher NT/EHNT ratio in the subjects with two mutated alleles of CYP2D6 than in those with no mutated alleles of CYP2D6 was observed (no mutated alleles vs. two mutated alleles: 0.73 +/- 0.39 vs. 1.31 +/- 0.81, p = 0.068). A trend for higher plasma concentrations of total hydroxylated metabolites of AT (EHAT + ZHAT) corrected for dose and body weight in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 was found (no mutated alleles vs. two mutated alleles: 9.5 +/- 5.8 vs. 17.8 +/- 8.9, p = 0.051). Therefore, the genotype of CYP2C19 is one of the important determinants of the plasma concentrations of AT and the capacity to desmethylate AT. Mother compound AT is shunted via hydroxylation pathways from AT to EHAT and ZHAT in the subjects with homozygotes of mutated alleles of CYP2C19 in order to compensate for the decreased capacity to desmethylate AT.
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Affiliation(s)
- Kazutaka Shimoda
- Department of Psychiatry, Shiga University of Medical Science, Shiga, Japan.
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Abstract
This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.
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Affiliation(s)
- Slobodan Rendic
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia.
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Kidd RS, Curry TB, Gallagher S, Edeki T, Blaisdell J, Goldstein JA. Identification of a null allele of CYP2C9 in an African-American exhibiting toxicity to phenytoin. PHARMACOGENETICS 2001; 11:803-8. [PMID: 11740344 DOI: 10.1097/00008571-200112000-00008] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cytochrome P450 (CYP) 2C9 is the principal enzyme responsible for the metabolism of numerous clinically important drugs. Two polymorphic alleles CYP2C9*2 and CYP2C9*3 have been documented which affect the metabolism and clinical toxicity of drugs such as phenytoin, warfarin, glipizide, and tolbutamide. The present study reports the first example of a null polymorphism in CYP2C9. This mutation dramatically affects the half-life and clinical toxicity of phenytoin. The study subject was a female African-American presented to the emergency department with phenytoin toxicity evidenced by mental confusion, slurred speech, memory loss and the inability to stand. She exhibited extremely poor clearance of phenytoin with an elimination half-life of approximately 13 days. Genotyping studies demonstrated that the patient did not possess any known variant CYP2C9 alleles. Phenytoin is metabolized to a minor extent by the polymorphic CYP2C19, but this individual did not possess any variant CYP2C19 alleles. Sequencing studies revealed that the individual was homozygous for a new CYP2C9 allele (CYP2C9*6) with the deletion of an adenine at base pair 818 of the cDNA. The clearance of phenytoin in this individual is estimated to be approximately 17% of that observed in normal patients. The frequency of this allele was 0.6% (95% confidence limits of 0.1 to 3.5%) in 79 African-Americans and 0% (95% confidence limits of 0 to 1.1%) in 172 Caucasians. The study also demonstrates the severe clinical consequences to patients with a null mutation in CYP2C9 after treatment with normal doses of phenytoin.
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Affiliation(s)
- R S Kidd
- Department of Biopharmaceutical Sciences, Bernard J. Dunn School of Pharmacy, Shenandoah University, Winchester, VA 22601, USA.
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Ramamoorthy Y, Tyndale RF, Sellers EM. Cytochrome P450 2D6.1 and cytochrome P450 2D6.10 differ in catalytic activity for multiple substrates. PHARMACOGENETICS 2001; 11:477-87. [PMID: 11505218 DOI: 10.1097/00008571-200108000-00003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CYP2D6 is involved in the metabolism of several classes of drugs, including tricyclic antidepressants, selective serotonin reuptake inhibitors and various amphetamines. CYP2D6*10 is an allelic variant, producing an enzyme with Pro34Ser and Ser486Thr amino acid substitutions. Approximately 75% of Asians possess the *10 allele. We sought to further characterize CYP2D6.10 catalytically in vitro in a baculovirus expression system using various substrates and inhibitors, in comparison to CYP2D6.1 (wild-type). Using dextromethorphan (DEX), P-methoxyamphetamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and (+/-)3,4-methylenedioxymethamphetamine (MDMA), the ratios of intrinsic clearance (Vmax/Km) of *1 to *10 were 50, 34, 22 and 123, respectively. The CYP2D6 substrates amitriptyline, and (+) and (-) methamphetamine (MAMP) are both p-hydroxylated and N-demethylated (NDM). The intrinsic clearance *1/*10 ratios were 42, 30 and 67 for the p-hydroxylation; and 60, 120 and 157 for the NDM, respectively, illustrating chemical pathway and enantiomeric selectivity for MAMP. It was apparent that (+) and (-) MAMP NDM and MDMA demethylenation were most significantly different in CYP2D6.10. Using DEX as the substrate, the ratios of Ki(*10)/Ki(*1) for inhibitors were: budipine (1.3), sparteine (1.6), debrisoquine (8.1), fluoxetine (16), norfluoxetine (30), paroxetine (14), MDMA (21) and MMDA-2 (7.1), indicating that CYP2D6.10 shows drug-specific altered susceptibility to inhibition. Taken together, these data suggest that CYP2D6*10/*10 individuals may be expected to require different drug doses; and show altered susceptibility to toxicity, interaction risk and, in the case of the amphetamines, drug dependence and toxicity compared to CYP2D6*1/*1 individuals.
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Affiliation(s)
- Y Ramamoorthy
- Department of Pharmacology, University of Toronto, Toronto, Canada
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Gervasini G, Martínez C, Agúndez JA, García-Gamito FJ, Benítez J. Inhibition of cytochrome P450 2C9 activity in vitro by 5-hydroxytryptamine and adrenaline. PHARMACOGENETICS 2001; 11:29-37. [PMID: 11207028 DOI: 10.1097/00008571-200102000-00004] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In the present study, the occurrence of a modulatory effect of 14 neurotransmitters, precursors and metabolites on the cytochrome P450 2C9 (CYP2C9) enzyme activity, as determined by diclofenac 4-hydroxylation, was studied in human liver microsomes. Two indoleamines, 5-hydroxytryptamine (5-HT) and adrenaline, showed a non-competitive-type inhibitory effect of approximately 90% of the diclofenac 4-hydroxylase activity, with Ki values of 63.5 (0.7 and 156 (89.3 microM, respectively. The rest of substances analysed were weak inhibitors or had no inhibitory effect. CYP2C subfamily is present in human brain, although CYP2C9 isozyme has not yet been identified in this tissue, and CYP2C9 is involved in the metabolism of psychoactive drugs. Therefore, the fact that endogenous compounds could modulate the CYP2C9 activity, suggests that an hypothetical local activity of brain CYP2C9 might be susceptible to regulatory mechanisms. The possible clinical implications of this modulation are discussed.
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Affiliation(s)
- G Gervasini
- Department of Pharmacology, Medical School, University of Extremadura, Badajoz, Spain
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Ong CE, Coulter S, Birkett DJ, Bhasker CR, Miners JO. The xenobiotic inhibitor profile of cytochrome P4502C8. Br J Clin Pharmacol 2000; 50:573-80. [PMID: 11136296 PMCID: PMC2015019 DOI: 10.1046/j.1365-2125.2000.00316.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To investigate inhibition of recombinant CYP2C8 by: (i) prototypic CYP isoform selective inhibitors (ii) imidazole/triazole antifungal agents (known inhibitors of CYP), and (iii) certain CYP3A substrates (given the apparent overlapping substrate specificity of CYP2C8 and CYP3A). METHODS CYP2C8 and NADPH-cytochrome P450 oxidoreductase were coexpressed in Spodoptera frugiperda (Sf21) cells using the baculovirus expression system. CYP isoform selective inhibitors, imidazole/triazole antifungal agents and CYP3A substrates were screened for their inhibitory effects on CYP2C8-catalysed torsemide tolylmethylhydroxylation and, where appropriate, the kinetics of inhibition were characterized. The conversion of torsemide to its tolylmethylhydroxy metabolite was measured using an h.p.l.c. procedure. RESULTS At concentrations of the CYP inhibitor 'probes' employed for isoform selectivity, only diethyldithiocarbamate and ketoconazole inhibited CYP2C8 by > 10%. Ketoconazole, at an added concentration of 10 microM, inhibited CYP2C8 by 89%. Another imidazole, clotrimazole, also potently inhibited CYP2C8. Ketoconazole and clotrimazole were both noncompetitive inhibitors of CYP2C8 with apparent Ki values of 2.5 microM. The CYP3A substrates amitriptyline, quinine, terfenadine and triazolam caused near complete inhibition (82-91% of control activity) of CYP2C8 at concentrations five-fold higher than the known CYP3A Km. Kinetic studies with selected CYP3A substrates demonstrated that most inhibited CYP2C8 noncompetitively. Apparent Ki values for midazolam, quinine, terfenadine and triazolam ranged from 5 to 25 microM. CONCLUSIONS Inhibition of CYP2C8 occurred at concentrations of ketoconazole and diethyldithiocarbamate normally employed for selective inhibition of CYP3A and CYP2E1, respectively. Some CYP3A substrates have the capacity to inhibit CYP2C8 activity and this may have implications for inhibitory drug interactions in vivo.
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Affiliation(s)
- C E Ong
- Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, Australia
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Moreno MA, Castro D, Frutos P, Ballesteros MP, Lastres JL. Liquid chromatographic determination of methylparaben and propylparaben in nortriptyline hydrochloride oil-water microemulsions. Chromatographia 2000. [DOI: 10.1007/bf02789756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Haritos VS, Ghabrial H, Ahokas JT, Ching MS. Role of cytochrome P450 2D6 (CYP2D6) in the stereospecific metabolism of E- and Z-doxepin. PHARMACOGENETICS 2000; 10:591-603. [PMID: 11037801 DOI: 10.1097/00008571-200010000-00003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The tricyclic antidepressant, doxepin, is formulated as an irrational mixture of E (trans) and Z (cis) stereoisomers (85%: 15%). We examined the stereoselective metabolism of doxepin in vitro, with the use of human liver microsomes, recombinant CYP2D6 and gas chromatography-mass spectrometry. In human liver microsomes over the concentration range 5-1500 microM, the rate of Z-doxepin N-demethylation exceeded that of E-doxepin above 100 microM in two of three livers. Eadie-Hofstee plots were curvilinear indicating the involvement of several enzymes in N-demethylation. Coincubation of doxepin with 7,8-naphthoflavone and ketoconazole reduced the rates of N-demethylation of E- and Z-doxepin by 30-50% and 40-60%, respectively, suggesting the involvement of CYP1A and CYP3A4, whilst quinidine had little effect on N-demethylation. In contrast, doxepin hydroxylation was exclusively stereo-specific; E-doxepin and E-N-desmethyldoxepin were hydroxylated with high affinity in liver microsomes and by recombinant CYP2D6 (Km in the range of 5-8 microM), but there was no evidence of Z-doxepin hydroxylation. In 'metabolic consumption' experiments with liver microsomes (having measurable CYP2D6 activity) and initial substrate concentration of 1 microM, the consumption of E-doxepin was greater (P < 0.05, n = 5) than that of Z-doxepin. Quinidine inhibited the consumption of E-doxepin but did not affect the consumption of Z-doxepin. With N-desmethyldoxepin, quinidine inhibited the consumption of E-N-desmethyl-doxepin whereas Z-N-desmethyldoxepin appeared to be a terminal oxidative metabolite. In summary, CYP2D6 is a major oxidative enzyme in doxepin metabolism; predominantly catalysing hydroxylation with an exclusive preference for the E-isomers. The relatively more rapid metabolism of E-isomeric forms, and the limited metabolic pathways for the Z-isomers may explain the apparent enrichment of Z-N-desmethyldoxepin that is observed in vivo.
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Affiliation(s)
- V S Haritos
- Key Centre for Applied and Nutritional Toxicology, RMIT-University, Victoria, Australia
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Zalma A, von Moltke LL, Granda BW, Harmatz JS, Shader RI, Greenblatt DJ. In vitro metabolism of trazodone by CYP3A: inhibition by ketoconazole and human immunodeficiency viral protease inhibitors. Biol Psychiatry 2000; 47:655-61. [PMID: 10745059 DOI: 10.1016/s0006-3223(99)00176-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Pharmacologic treatment of emotional disorders in HIV-infected patients can be more easily optimized by understanding of potential interactions of psychotropic drugs with medications used to treat HIV infection and its sequelae. METHODS Biotransformation of the antidepressant trazodone to its principal metabolite, meta-chlorophenylpiperazine (mCPP), was studied in vitro using human liver microsomes and heterologously expressed individual human cytochromes. Interactions of trazodone with the azole antifungal agent, ketoconazole, and with human immunodeficiency virus protease inhibitors (HIVPIs) were studied in the same system. RESULTS Formation of mCPP from trazodone in liver microsomes had a mean (+/- SE) K(m) value of 163 (+/- 21) micromol/L. Ketoconazole, a relatively specific CYP3A inhibitor, impaired mCPP formation consistent with a competitive mechanism, having an inhibition constant (K(i)) of 0.12 (+/- 0.01) micromol/L. Among heterologously expressed human cytochromes, only CYP3A4 mediated formation of mCPP from trazodone; the K(m) was 180 micromol/L, consistent with the value in microsomes. The HIVPI ritonavir was a potent inhibitor of mCPP formation in liver microsomes (K(i) = 0.14 +/- 0.04 micromol/L). The HIVPI indinavir was also a strong inhibitor, whereas saquinavir and nelfinavir were weaker inhibitors. CONCLUSIONS CYP3A-mediated clearance of trazodone is inhibited by ketoconazole, ritonavir and indinavir, and indicates the likelihood of pharmacokinetic interactions in vivo.
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Affiliation(s)
- A Zalma
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA
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Ballesteros MP, Frutos P, Lastres JL, Castro D. Comparison of UV spectrophotometric and LC methods for the determination of nortriptyline hydrochloride in polysorbate 80 based oil/water (o/w) microemulsions. J Pharm Biomed Anal 2000; 22:287-94. [PMID: 10719911 DOI: 10.1016/s0731-7085(99)00285-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A new rapid, reliable and specific UV spectrophotometric method was developed for the determination of nortriptyline hydrochloride formulated into o/w microemulsions. The UV spectra of nortriptyline standard solution in methanol and placebo (microemulsion without nortriptyline) were recorded over the wavelength range 200-600 nm and the spectra for placebo and nortriptyline loaded microemulsion were recorded over the range 260-400 nm in order to determine the overlapping that might appears, and hence to set the wavelength that could be used for the quantitative analysis. This method was validated and compared with a liquid chromatography (LC) procedure used for the quantitative analysis of the drug. Both methods showed excellent precision and accuracy with RSD values of 2.37 and 1.41%, respectively, for the LC method, and values of 1.24 and 2.88%, respectively, for the UV spectrophotometric method. The established linearity range was 10-50 microg ml(-1) (r2 = 0.9985) and 20-60 microg ml(-1) (r2 = 0.9979) for the HPLC and UV spectrophotometric methods respectively. The recoveries of nortriptyline from spiked placebos were > 95% for both methods over the linear range. The methods have been successfully used for determining the nortriptyline content of microemulsions and for evaluating the chemical stability of the drug in nortriptyline-loaded microemulsions.
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de Groot MJ, Ackland MJ, Horne VA, Alex AA, Jones BC. A novel approach to predicting P450 mediated drug metabolism. CYP2D6 catalyzed N-dealkylation reactions and qualitative metabolite predictions using a combined protein and pharmacophore model for CYP2D6. J Med Chem 1999; 42:4062-70. [PMID: 10514276 DOI: 10.1021/jm991058v] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combined protein and pharmacophore model for cytochrome P450 2D6 (CYP2D6) has been extended with a second pharmacophore in order to explain CYP2D6 catalyzed N-dealkylation reactions. A group of 14 experimentally verified N-dealkylation reactions form the basis of this second pharmacophore. The combined model can now accommodate both the usual hydroxylation and O-demethylation reactions catalyzed by CYP2D6, as well as the less common N-dealkylation reactions. The combined model now contains 72 metabolic pathways catalyzed by CYP2D6 in 51 substrates. The model was then used to predict the involvement of CYP2D6 in the metabolism of a "test set" of seven compounds. Molecular orbital calculations were used to suggest energetically favorable sites of metabolism, which were then examined using modeling techniques. The combined model correctly predicted 6 of the 8 observed metabolites. For the well-established CYP2D6 metabolic routes, the predictive value of the current combined protein and pharmacophore model is good. Except for the highly unusual metabolism of procainamide and ritonavir, the known metabolites not included in the development of the model were all predicted by the current model. Two possible metabolites have been predicted by the current model, which have not been detected experimentally. In these cases, the model may be able to guide experiments. P450 models, like the one presented here, have wide applications in the drug design process which will contribute to the prediction and elimination of polymorphic metabolism and drug-drug interactions.
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Affiliation(s)
- M J de Groot
- Department of Molecular Informatics, Pfizer Central Research, Sandwich, Kent CT13 9NJ, United Kingdom
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Strolin Benedetti M, Bani M. Metabolism-based drug interactions involving oral azole antifungals in humans. Drug Metab Rev 1999; 31:665-717. [PMID: 10461546 DOI: 10.1081/dmr-100101941] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Daniel WA, Syrek M, Wójcikowski J. The influence of selective serotonin reuptake inhibitors on the plasma and brain pharmacokinetics of the simplest phenothiazine neuroleptic promazine in the rat. Eur Neuropsychopharmacol 1999; 9:337-44. [PMID: 10422895 DOI: 10.1016/s0924-977x(99)00006-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present study was to investigate a possible impact of the three selective serotonin reuptake inhibitors (SSRIs) fluoxetine, fluvoxamine and sertraline on the pharmacokinetics of promazine in a steady state in rats. Promazine was administered twice a day for 2 weeks, alone or jointly with one of the antidepressants. Concentrations of promazine and its two main metabolites (N-desmethylpromazine and sulfoxide) in the plasma and brain were measured at 30 min and 6 and 12 h after the last dose of the drugs. All the investigated SSRIs increased the plasma and brain concentrations of promazine up to 300% of the control value, their effect being most pronounced after 30 min and 6 h. Moreover, simultaneous increases in the promazine metabolites' concentrations and in the promazine-metabolite concentration ratios were observed. In vitro studies with liver microsomes of rats treated chronically with promazine, SSRIs or their combination did not show any significant changes in the concentrations of cytochromes P-450 and b-5. However, treatment with fluoxetine, alone or in a combination with promazine, decreased the rates of promazine N-demethylation and sulfoxidation. A similar effect was observed in the case of promazine and fluvoxamine combination. Kinetic studies into promazine metabolism, carried out on control liver microsomes in the absence or presence of SSRIs added in vitro, demonstrated competitive inhibition of both N-demethylation and sulfoxidation by the antidepressants. The results of in vivo and in vitro studies indicate the following mechanisms of the observed interactions: (a) competition for an active site of promazine N-demethylase and sulfoxidase; (b) adaptive changes in cytochrome P-450, produced by chronic treatment with fluoxetine or fluvoxamine; (c) additionally, increases in the sum of concentrations of promazine+ metabolites, produced by fluoxetine and sertraline in vivo, suggest simultaneous inhibition of another, not investigated by us, metabolic pathway of promazine, e.g. hydroxylation. In conclusion, all the three SSRIs administered chronically in pharmacological doses, increase the concentrations of promazine in the blood plasma and brain of rats by inhibiting different metabolic pathways of the neuroleptic. Assuming that similar interactions occur in humans, reduced doses of phenotiazines should be considered when one of the above antidepressants is to be given jointly.
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Affiliation(s)
- W A Daniel
- Polish Academy of Sciences, Institute of Pharmacology, Kraków.
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Roos PH. Common multiple interactions of tricyclic anti-depressants and orphenadrine with liver microsomal cytochrome P450 enzymes of the rat. Xenobiotica 1999; 29:629-40. [PMID: 10426561 DOI: 10.1080/004982599238443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
1. Interactions of tricylic anti-depressants (TCA) and structurally related drugs with rat microsomal cytochromes P450 were studied including competitive inhibition of enzymatic activities and formation of P450 metabolite complexes. 2. All compounds examined that carry a methylated aminoalkyl sidechain formed metabolite complexes with microsomal P450 of the untreated male rat. The extent of complex formation is only slightly altered by rat pre-treatment with P450 inducers indicating that mainly constitutive P450 enzymes are involved. 3. The kinetics of in vitro complex formation differed for the di- and monomethylamino derivatives of the TCA showing either a sigmoidal or hyperbolic shape respectively. Considerable auto-inhibition of complex formation is observed at concentrations > 100 microM only with the dimethyl derivatives. 4. Besides metabolite complex formation, a further effect of the drugs is competitive inhibition of the CYP2B-dependent pentoxyresorufin O-dealkylation. The inhibitory potential of the drugs depends on their degree of N-alkyl substitution. Correspondingly, the Ki is in the range of 2.8-7.1, 0.1-0.2 and 0.01 microM for the dimethyl-, monomethyl- and unsubstituted drugs respectively. 5. It has been shown that P450 interactions with tricyclic anti-depressants include several types of mechanisms and several P450 enzymes. It might be pharmacologically important that the dimethylamino compounds are demethylated in vivo by cytochromes P450 giving rise to more potent P450 inhibitors compared with the parent compounds.
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Affiliation(s)
- P H Roos
- Institute for Physiological Chemistry, Division of Bioenergetics, Ruhr-University Bochum, Germany.
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Schmider J, von Moltke LL, Shader RI, Harmatz JS, Greenblatt DJ. Extrapolating in vitro data on drug metabolism to in vivo pharmacokinetics: evaluation of the pharmacokinetic interaction between amitriptyline and fluoxetine. Drug Metab Rev 1999; 31:545-60. [PMID: 10335452 DOI: 10.1081/dmr-100101935] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recently, models have been proposed to extrapolate in vitro data on the influence of inhibitors on drug metabolism to in vivo decrement in drug clearance. Many factors influence drug clearance such as age, gender, habits, diet, environment, liver disease, heredity, and other drugs. In vitro investigation of hepatic cytochrome P450 activity has generally centered on genetic influences and interactions with other drugs. This group of enzymes is involved in many, although not all, drug interactions. The interaction of amitriptyline and fluoxetine is an example. Of the different in vitro paradigms, interaction studies utilizing human liver microsomal preparations have proved to be the most generally applicable for in vitro scaling models. Assuming Michaelis-Menten conditions and applying nonlinear regression, a hybrid inhibition constant (Ki) can be generated that allows classification of the inhibitory potency of an inhibitor toward a specific reaction. This constant is largely independent of the substrate concentration, but in vivo relevance is critically dependent on the inhibitor concentration in the site of metabolic activity, the liver cell cytosol. Many lipophilic drugs are extensively bound to plasma protein but, nonetheless, demonstrate extensive partitioning into liver tissue. This is not compatible with diffusion only of the unbound drug fraction into liver cells. The introduction of a partition factor, based on data from a number of possible sources, provided a reasonable basis for the scaling of in vitro data to in vivo conditions. Many interactions could be reconstructed or predicted with greater accuracy and clinical relevance for interactions such as terfenadine or midazolam and ketoconazole. Even for less marked interactions such as amitriptyline and fluoxetine, this model provides a forecast consistent with the clinically observed range of 22-45% reduction in oral clearance, although this interaction is complicated by the presence of two inhibitors, fluoxetine and norfluoxetine. The concept of in vitro-in vivo scaling is promising and might ultimately yield a fast and more cost-effective screening for drug interactions with reduced human drug exposure and risk.
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Affiliation(s)
- J Schmider
- Department of Clinical Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts, USA.
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