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Quimby JM, Lorbach SK, Saffire A, Kennedy A, Wittenburg LA, Aarnes TK, Creighton KJ, Jones SE, Paschall RE, King EM, Bruner CE, Wallinger JN, van Haaften KA. Serum concentrations of gabapentin in cats with chronic kidney disease. J Feline Med Surg 2022; 24:1260-1266. [PMID: 35195476 PMCID: PMC9395545 DOI: 10.1177/1098612x221077017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVES The purpose of this study was to assess serum concentrations of gabapentin in cats with chronic kidney disease (CKD) vs clinically healthy cats. METHODS Five healthy cats were enrolled in a pharmacokinetic study. A single 20 mg/kg dose of gabapentin was administered orally and blood was obtained at 0, 0.25, 0.5, 1, 1.5, 2, 3, 4, 8, 12, 24 and 36 h via a jugular catheter. Serum gabapentin concentrations were measured using liquid chromatography coupled to tandem mass spectrometry. Non-compartmental pharmacokinetic analysis was performed. The same five healthy cats plus 25 cats with stable International Renal Interest Society stage 2 (n = 14) and 3 (n = 11) CKD were enrolled in a limited sampling study. Cats in both groups received a single 10 mg/kg dose of gabapentin, and serum gabapentin concentrations and compliance scores were obtained 3 and 8 h post-administration. RESULTS Cats with CKD had significantly higher dose-normalized serum gabapentin concentrations than normal cats at 3 h (P = 0.0012 CKD vs normal 10 mg/kg; P = 0.008 CKD vs normal 20 mg/kg) and 8 h (P <0.0001 CKD vs normal 10 mg/kg; P <0.0001 CKD vs normal 20 mg/kg). Both 3 and 8 h dose-normalized serum gabapentin concentrations were significantly correlated with serum creatinine (3 h: P = 0.03, r = 0.39; 8 h: P = 0.001, r = 0.57) and symmetric dimethylarginine (3 h: P = 0.03, r = 0.41; 8 h: P = 0.007, r = 0.48). There was a significant correlation between 3 h serum gabapentin concentrations and compliance scores (P = 0.0002, r = 0.68). CONCLUSIONS AND RELEVANCE Cats with CKD that received 10 mg/kg of gabapentin had significantly higher dose-normalized serum concentrations than normal cats that received 20 mg/kg, supporting the need to dose-reduce in this patient population.
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Affiliation(s)
- Jessica M Quimby
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
- Jessica Quimby DVM, PhD, DACVIM (Internal Medicine), Department of Veterinary Clinical Sciences, The Ohio State University Veterinary Medical Center, 601 Vernon Tharp Drive, Columbus, OH 43210, USA
| | - Sarah K Lorbach
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | | | | | - Luke A Wittenburg
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California – Davis, CA, USA
| | - Turi K Aarnes
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Karina J Creighton
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Sarah E Jones
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Rene E Paschall
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Emily M King
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Clara E Bruner
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - Jessica N Wallinger
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
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Yamamoto PA, Benzi JRDL, Dach F, Moraes NVD. Therapeutic drug monitoring of gabapentin: the applicability in patients with neuropathic pain. BRAZ J PHARM SCI 2022. [DOI: 10.1590/s2175-97902022e191073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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3
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Bouchard J, Yates C, Calello DP, Gosselin S, Roberts DM, Lavergne V, Hoffman RS, Ostermann M, Peng A, Ghannoum M. Extracorporeal Treatment for Gabapentin and Pregabalin Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup. Am J Kidney Dis 2021; 79:88-104. [PMID: 34799138 DOI: 10.1053/j.ajkd.2021.06.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/11/2021] [Indexed: 11/11/2022]
Abstract
Toxicity from gabapentin and pregabalin overdose is commonly encountered. Treatment is supportive, and the use of extracorporeal treatments (ECTRs) is controversial. The EXTRIP workgroup conducted systematic reviews of the literature and summarized findings following published methods. Thirty-three articles (30 patient reports and 3 pharmacokinetic studies) met the inclusion criteria. High gabapentinoid extracorporeal clearance (>150mL/min) and short elimination half-life (<5 hours) were reported with hemodialysis. The workgroup assessed gabapentin and pregabalin as "dialyzable" for patients with decreased kidney function (quality of the evidence grade as A and B, respectively). Limited clinical data were available (24 patients with gabapentin toxicity and 7 with pregabalin toxicity received ECTR). Severe toxicity, mortality, and sequelae were rare in cases receiving ECTR and in historical controls receiving standard care alone. No clear clinical benefit from ECTR could be identified although major knowledge gaps were acknowledged, as well as costs and harms of ECTR. The EXTRIP workgroup suggests against performing ECTR in addition to standard care rather than standard care alone (weak recommendation, very low quality of evidence) for gabapentinoid poisoning in patients with normal kidney function. If decreased kidney function and coma requiring mechanical ventilation are present, the workgroup suggests performing ECTR in addition to standard care (weak recommendation, very low quality of evidence).
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Affiliation(s)
- Josée Bouchard
- Research Center, CIUSSS du Nord-de-l'île-de-Montréal, Hôpital du Sacré-Coeur de Montréal, University of Montreal, Montreal, Quebec, Canada
| | - Christopher Yates
- Emergency Department and Clinical Toxicology Unit, Hospital Universitari Son Espases, SAMU 061, Balears, Spain; IdISBa Clinical Toxicology Workgroup, Palma de Mallorca, Spain
| | - Diane P Calello
- Department of Emergency Medicine, Rutgers New Jersey Medical School, Newark, New Jersey; New Jersey Poison Information and Education System, Newark, New Jersey
| | - Sophie Gosselin
- Centre Intégré de Santé et de Services Sociaux, Montérégie-Centre Emergency Department, Hôpital Charles-Lemoyne, Greenfield Park, Quebec, Canada; Department of Emergency Medicine, McGill University, Montreal, Quebec, Canada; Centre Antipoison du Québec, Quebec City, Quebec, Canada
| | - Darren M Roberts
- Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Sydney, Australia; St Vincent's Clinical School, University of New South Wales, Sydney, Australia; Drug Health Services, Royal Prince Alfred Hospital, Sydney, Australia
| | - Valéry Lavergne
- Research Center, CIUSSS du Nord-de-l'île-de-Montréal, Hôpital du Sacré-Coeur de Montréal, University of Montreal, Montreal, Quebec, Canada
| | - Robert S Hoffman
- Division of Medical Toxicology, Ronald O. Perelman Department of Emergency Medicine, Grossman School of Medicine, New York University, New York, New York
| | - Marlies Ostermann
- Department of Critical Care & Nephrology, King's College, London, United Kingdom; Guy's & St Thomas Hospital, London, United Kingdom
| | - Ai Peng
- Department of Nephrology and Rheumatology, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
| | - Marc Ghannoum
- Research Center, CIUSSS du Nord-de-l'île-de-Montréal, Hôpital du Sacré-Coeur de Montréal, University of Montreal, Montreal, Quebec, Canada.
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Hatton GE, Kregel HR, Pedroza C, Puzio TJ, Adams SD, Wade CE, Kao LS, Harvin JA. Age-related Opioid Exposure in Trauma: A Secondary Analysis of the Multimodal Analgesia Strategies for Trauma (MAST) Randomized Trial. Ann Surg 2021; 274:565-571. [PMID: 34506311 PMCID: PMC8783293 DOI: 10.1097/sla.0000000000005065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Evaluate the effect of age on opioid consumption after traumatic injury. SUMMARY BACKGROUND DATA Older trauma patients receive fewer opioids due to decreased metabolism and increased complications, but adequacy of pain control is unknown. We hypothesized that older trauma patients require fewer opioids to achieve adequate pain control. METHODS A secondary analysis of the multimodal analgesia strategies for trauma Trial evaluating the effectiveness of 2 multimodal pain regimens in 1561 trauma patients aged 16 to 96 was performed. Older patients (≥55 years) were compared to younger patients. Median daily oral morphine milligram equivalents (MME) consumption, average numeric rating scale pain scores, complications, and death were assessed. Multivariable analyses were performed. RESULTS Older patients (n = 562) had a median age of 68 years (interquartile range 61-78) compared to 33 (24-43) in younger patients. Older patients had lower injury severity scores (13 [9-20] vs 14 [9-22], P = 0.004), lower average pain scores (numeric rating scale 3 [1-4] vs 4 [2-5], P < 0.001), and consumed fewer MME/day (22 [10-45] vs 52 [28-78], P < 0.001). The multimodal analgesia strategies for trauma multi-modal pain regimen was effective at reducing opioid consumption at all ages. Additionally, on multivariable analysis including pain score adjustment, each decade age increase after 55 years was associated with a 23% reduction in MME/day consumed. CONCLUSIONS Older trauma patients required fewer opioids than younger patients with similar characteristics and pain scores. Opioid dosing for post-traumatic pain should consider age. A 20 to 25% dose reduction per decade after age 55 may reduce opioid exposure without altering pain control.
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Affiliation(s)
- Gabrielle E Hatton
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Surgical Trials and Evidence-based Practice, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - Heather R Kregel
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Surgical Trials and Evidence-based Practice, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - Claudia Pedroza
- Department of Pediatrics, McGovern Medical School at UTHealth, Houston, Texas
| | - Thaddeus J Puzio
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - Sasha D Adams
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - Charles E Wade
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - Lillian S Kao
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Surgical Trials and Evidence-based Practice, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
| | - John A Harvin
- Department of Surgery, Division of Acute Care Surgery, McGovern Medical School at UTHealth, Houston, Texas
- Center for Translational Injury Research, Houston, Texas
- Center for Clinical Research and Evidence Based Medicine, McGovern Medical School at UTHealth, Houston, Texas
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Dal Bello F, Medana C, Zorzi M, Kuck B, Fabbri D, Calza P. Liquid chromatography/mass spectrometry analytical determination of gabapentin transformation products by heterogeneous photocatalysis and environmental evaluation. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8925. [PMID: 32845556 DOI: 10.1002/rcm.8925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Gabapentin is a drug used to treat epilepsy and peripheral neuropathic pain. It is an analog of gamma-aminobutyric acid, and it is a selective blocker of voltage-gated calcium channels. The drug is excreted unmetabolized; it is stable in the environment and is classified as a persistent mobile organic contaminant. Because wastewater treatment plants (WWTPs) are not completely efficient, some bioactive molecules may be released unaltered into the environment. The aim of this study was to provide information about degradation pathways of gabapentin in water by studying its photoinduced transformation products (TPs) through laboratory simulation experiments. Gabapentin and its TPs were monitored in influent and effluent water samples from WWTPs in Germany and Italy. METHODS The laboratory simulation used heterogeneous photodegradation mediated by titanium dioxide (TiO2 ). Chromatographic separation was achieved using a C18 reverse-phase column, and the structural identification of TPs was performed using high-resolution electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and multistage MSn experiments. RESULTS Several TPs were observed during TiO2 photodegradation. Nine new compounds were detected, and potential structures were assigned by studying the fragmentation pathways of the [M + H]+ ions of these TPs and gabapentin. Gabapentin and some of the newly identified TPs were found in environmental samples from WWTPs. CONCLUSIONS The developed high-performance liquid chromatography/high-resolution mass spectrometry method was used to identify TPs from gabapentin. It was then successfully applied to real environmental samples to monitor the TPs as potential environmental pollutants.
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Affiliation(s)
- Federica Dal Bello
- Molecular Biotechnology and Health Sciences Department, Università degli Studi di Torino, Torino, Italy
| | - Claudio Medana
- Molecular Biotechnology and Health Sciences Department, Università degli Studi di Torino, Torino, Italy
| | - Michael Zorzi
- Molecular Biotechnology and Health Sciences Department, Università degli Studi di Torino, Torino, Italy
| | - Bertram Kuck
- Institute of Sanitary, Engineering, Water Quality and Solid Waste Management, University of Stuttgart, Stuttgart, Germany
| | - Debora Fabbri
- Chemistry Department, Università degli Studi di Torino, Torino, Italy
| | - Paola Calza
- Chemistry Department, Università degli Studi di Torino, Torino, Italy
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Roberti R, Palleria C, Nesci V, Tallarico M, Di Bonaventura C, Cerulli Irelli E, Morano A, De Sarro G, Russo E, Citraro R. Pharmacokinetic considerations about antiseizure medications in the elderly. Expert Opin Drug Metab Toxicol 2020; 16:983-995. [DOI: 10.1080/17425255.2020.1806236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Roberta Roberti
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
| | - Caterina Palleria
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
| | - Valentina Nesci
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
| | - Martina Tallarico
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
| | - Carlo Di Bonaventura
- Neurology Unit, Department of Human Neurosciences, “Sapienza” University, Rome, Italy
| | | | - Alessandra Morano
- Neurology Unit, Department of Human Neurosciences, “Sapienza” University, Rome, Italy
| | | | - Emilio Russo
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
| | - Rita Citraro
- Science of Health Department, School of Medicine, University of Catanzaro, Italy
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Schmid Y, Navarini A, Thomas ZRM, Pfleiderer B, Krähenbühl S, Mueller SM. Sex differences in the pharmacology of itch therapies-a narrative review. Curr Opin Pharmacol 2019; 46:122-142. [PMID: 31299512 DOI: 10.1016/j.coph.2019.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 02/08/2023]
Abstract
BACKGROUND Chronic itch is the most common skin-related condition, associated with a high psychosocial and economic burden. In recent years, increasing evidence of sex differences in the perception, clinical presentation and treatment requirements of itch points towards potential benefits when using sex-adapted therapies. It is well-known that body composition, absorption, metabolism, elimination and adverse drug reactions (ADRs) differ between sexes, but only little is known about the impact of sex in the pharmacology of itch treatments, which could help to rationalise sex-adapted treatment strategies. AIM To evaluate and review sex effects in the pharmacokinetics and /-dynamics of drugs used to treat itch. METHODS In this narrative review we performed a PubMed and MEDLINE (Ovid) search using the terms (itch OR pruritus) AND (gender OR sex) AND (drug OR medication OR pharmacokinetics OR pharmacodynamics). Additional searches were performed for the topical and systemic drugs recommended by the European Guideline on Chronic Pruritus. RESULTS We found numerous reports with variable levels of evidence of sex effects with respect to the pharmacokinetics and/or pharmacodynamics of 14 drug classes used for the treatment of itch, including a total of 19 systemic and 3 topical drugs. Women seem to present higher plasma levels of several drugs used in itch treatment, including tri- and tetracyclic antidepressants (e.g. doxepin, amitriptyline, mirtazapine), serotonin reuptake inhibitors (e.g. paroxetine, sertraline, fluoxetine), immunosuppressive drugs (e.g. cyclosporine, mycophenolate mofetil), serotonin receptor antagonists (e.g. ondansetron) and betablockers (e.g. propranolol). Adverse drug reactions (ADRs) were generally more common in women. Being female was reported to be an independent risk factor for QTc-prolongation associated with antihistamines and tetracyclic antidepressants. Additionally, women seem to be more prone to sedative effects of antihistamines, and to suffer from a higher frequency as well as severity of side effects with systemic calcineurin inhibitors, opioid agonists, and opioid antagonists. Women were also sensitised more often to topically applied drugs. Of note, apart from only one experimental study with capsaicin, none of these reports were designed specifically to assess the effect of sex (and gender) in the treatment of itch. DISCUSSION/CONCLUSION Our review supports previous reports that sex is of importance in the pharmacokinetics and /-dynamics of several drugs used to treat itch although those drugs were mostly evaluated for non-itch indications. However, the results are limited by methodological limitations evident in most studies such as underrepresentation of women in clinical trials. This emphasises the need to study the impact of sex (and gender) in future itch trials to yield better outcomes and prevent ADRs in both sexes.
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Affiliation(s)
- Yasmin Schmid
- Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland
| | | | | | - Bettina Pfleiderer
- Department of Clinical Radiology, University Hospital Münster and Medical Faculty, University of Münster, Germany; Competence Center Chronic Pruritus (KCP), University of Muenster, Germany
| | - Stephan Krähenbühl
- Clinical Pharmacology & Toxicology, University Hospital Basel, Switzerland
| | - Simon M Mueller
- Department of Dermatology, University Hospital Basel, Switzerland.
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Greenblatt HK, Greenblatt DJ. Gabapentin and Pregabalin for the Treatment of Anxiety Disorders. Clin Pharmacol Drug Dev 2019; 7:228-232. [PMID: 29579375 DOI: 10.1002/cpdd.446] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Yamamoto PA, Benzi JRL, Azeredo FJ, Dach F, Ianhez Júnior E, Zanelli CF, de Moraes NV. Pharmacogenetics-based population pharmacokinetic analysis of gabapentin in patients with chronic pain: Effect of OCT2 and OCTN1 gene polymorphisms. Basic Clin Pharmacol Toxicol 2018; 124:266-272. [PMID: 30192429 DOI: 10.1111/bcpt.13126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/04/2018] [Indexed: 01/11/2023]
Abstract
Gabapentin (GAB) is eliminated unchanged in urine, and organic cation transporters (OCT2 and OCTN1) have been shown to play a role in GAB renal excretion. This prospective clinical study aimed to evaluate the genetic polymorphisms effect on GAB pharmacokinetic (PK) variability using a population pharmacokinetic approach. Data were collected from 53 patients with chronic pain receiving multiple doses of GAB. Patients were genotyped for SLC22A2 c.808G>T and SLC22A4 c.1507C>T polymorphisms. Both polymorphisms' distribution followed the Hardy-Weinberg equilibrium. An one-compartment model with first-order absorption and linear elimination best described the data. The absorption rate constant, volume of distribution, and clearance estimated were 0.44 h-1 , 86 L, and 17.3 × (estimated glomerular filtration ratio/89.58)1.04 L/h, respectively. The genetic polymorphism SLC22A4 c.1507C>T did not have a significant influence on GAB absorption, distribution or elimination. Due to the low minor allelic frequency of SLC22A2 c.808G>T, further studies require higher number of participants to confirm its effect on GAB renal elimination. In conclusion, GAB clinical pharmacokinetics are strongly influenced by renal function and absorption process, but not by the OCTN1 (SLC22A4 c.1507C>T) polymorphism.
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Affiliation(s)
- Priscila A Yamamoto
- Department of Natural Products and Toxicology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Araraquara, Brazil
| | - Jhohann R L Benzi
- Department of Clinical Analyses, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, Brazil
| | | | - Fabíola Dach
- Department of Neurosciences, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, Brazil
| | | | - Cleslei F Zanelli
- Department of Biological Sciences, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Araraquara, Brazil
| | - Natália V de Moraes
- Department of Natural Products and Toxicology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Araraquara, Brazil
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Pharmacokinetic Factors to Consider in the Selection of Antiseizure Drugs for Older Patients with Epilepsy. Drugs Aging 2018; 35:687-698. [DOI: 10.1007/s40266-018-0562-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Conway JM, Eberly LE, Collins JF, Macias FM, Ramsay RE, Leppik IE, Birnbaum AK. Factors in Variability of Serial Gabapentin Concentrations in Elderly Patients with Epilepsy. Pharmacotherapy 2017; 37:1197-1203. [PMID: 28801938 PMCID: PMC9949609 DOI: 10.1002/phar.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES To characterize and quantify the variability of serial gabapentin concentrations in elderly patients with epilepsy. METHODS This study included 83 patients (age ≥ 60 yrs) from an 18-center randomized double-blind double-dummy parallel study from the Veterans Affairs Cooperative 428 Study. All patients were taking 1500 mg/day gabapentin. Within-person coefficient of variation (CV) in gabapentin concentrations, measured weekly to bimonthly for up to 52 weeks, then quarterly, was computed. Impact of patient characteristics on gabapentin concentrations (linear mixed model) and CV (linear regression) were estimated. RESULTS A total of 482 gabapentin concentration measurements were available for analysis. Gabapentin concentrations and intrapatient CVs ranged from 0.5 to 22.6 μg/ml (mean 7.9 μg/ml, standard deviation [SD] 4.1 μg/ml) and 2% to 79% (mean 27.9%, SD 15.3%), respectively, across all visits. Intrapatient CV was higher by 7.3% for those with a body mass index of ≥ 30 kg/m2 (coefficient = 7.3, p=0.04). CVs were on average 0.5% higher for each 1-unit higher CV in creatinine clearance (coefficient = 0.5, p=0.03) and 1.2% higher for each 1-hour longer mean time after dose (coefficient = 1.2, p=0.04). CONCLUSIONS Substantial intrapatient variability in serial gabapentin concentration was noted in elderly patients with epilepsy. Creatinine clearance, time of sampling relative to dose, and obesity were found to be positively associated with variability.
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Affiliation(s)
- Jeannine M. Conway
- Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota
| | - Lynn E. Eberly
- Division of Biostatistics, School of Public Health, University of Minnesota
| | | | | | | | - Ilo E. Leppik
- Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota,Department of Neurology, University of Minnesota
| | - Angela K. Birnbaum
- Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota
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