1
|
Tverdislov VA, Sidorova AE, Bagrova OE, Belova EV, Bystrov VS, Levashova NT, Lutsenko AO, Semenova EV, Shpigun DK. Chirality As a Symmetric Basis of Self-Organization of Biomacromolecules. Biophysics (Nagoya-shi) 2022. [DOI: 10.1134/s0006350922050190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
|
2
|
Shoemaker MB, Yoneda ZT, Crawford DM, Akers WS, Richardson T, Montgomery JA, Phillips S, Shyr Y, Saavedra P, Estrada J, Kanagasundram A, Shen ST, Michaud G, Crossley G, Ellis CR, Knollmann BC. A Mechanistic Clinical Trial Using ( R)- Versus (S)-Propafenone to Test RyR2 (Ryanodine Receptor) Inhibition for the Prevention of Atrial Fibrillation Induction. Circ Arrhythm Electrophysiol 2022; 15:e010713. [PMID: 36166682 PMCID: PMC9588733 DOI: 10.1161/circep.121.010713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 08/16/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND Experimental data suggest ryanodine receptor-mediated intracellular calcium leak is a mechanism for atrial fibrillation (AF), but evidence in humans is still needed. Propafenone is composed of two enantiomers that are equally potent sodium-channel blockers; however, (R)-propafenone is an ryanodine receptor inhibitor whereas (S)-propafenone is not. This study tested the hypothesis that ryanodine receptor inhibition with (R)-propafenone prevents induction of AF compared to (S)-propafenone or placebo in patients referred for AF ablation. METHODS Participants were randomized 4:4:1 to a one-time intravenous dose of (R)-propafenone, (S)-propafenone, or placebo. The study drug was given at the start of the procedure and an AF induction protocol using rapid atrial pacing was performed before ablation. The primary endpoint was 30 s of AF or atrial flutter. RESULTS A total of 193 participants were enrolled and 165 (85%) completed the study protocol (median age: 63 years, 58% male, 95% paroxysmal AF). Sustained AF and/or atrial flutter was induced in 60 participants (84.5%) receiving (R)-propafenone, 60 (80.0%) receiving (S)-propafenone group, and 12 (63.2%) receiving placebo. Atrial flutter occurred significantly more often in the (R)-propafenone (N=23, 32.4%) and (S)-propafenone (N=26, 34.7%) groups compared to placebo (N=1, 5.3%, P=0.029). There was no significant difference between (R)-propafenone and (S)-propafenone for the primary outcome of AF and/or atrial flutter induction in univariable (P=0.522) or multivariable analysis (P=0.199, adjusted for age and serum drug level). CONCLUSIONS There is no difference in AF inducibility between (R)-propafenone and (S)-propafenone at clinically relevant concentrations. These results are confounded by a high rate of inducible atrial flutter due to sodium-channel blockade. REGISTRATION https://clinicaltrials.gov; Unique Identifier: NCT02710669.
Collapse
Affiliation(s)
- M. Benjamin Shoemaker
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Zachary T. Yoneda
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Diane M. Crawford
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Wendell S. Akers
- Department of Pharmacology, Vanderbilt University School of Medicine
- Department of Pharmaceutical Sciences, Lipscomb University College of Pharmacy, Nashville, TN
| | - Travis Richardson
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Jay A. Montgomery
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Sharon Phillips
- Department of Biostatistics, Vanderbilt University School of Medicine
| | - Yu Shyr
- Department of Biostatistics, Vanderbilt University School of Medicine
| | - Pablo Saavedra
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - J.C. Estrada
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Arvindh Kanagasundram
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Sharon T. Shen
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Greg Michaud
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - George Crossley
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | - Christopher R. Ellis
- Division of Cardiology, Department of Medicine, Vanderbilt University Medical Center
| | | |
Collapse
|
3
|
Tran QT, Baek IH, Han NY, Yun HY, Chae JW. The Effect of CYP2D6 Phenotypes on the Pharmacokinetics of Propafenone: A Systematic Review and Meta-Analysis. Pharmaceutics 2022; 14:pharmaceutics14071446. [PMID: 35890339 PMCID: PMC9324789 DOI: 10.3390/pharmaceutics14071446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/04/2022] [Accepted: 07/08/2022] [Indexed: 02/04/2023] Open
Abstract
Propafenone (PPF) is a class 1C antiarrhythmic agent mainly metabolized by cytochrome (CYP) 2D6, CYP1A2, and CYP3A4. Previous studies have shown that CYP2D6 polymorphism influences the pharmacokinetics (PK) of PPF. However, the small sample sizes of PK studies can lead to less precise estimates of the PK parameters. Thus, this meta-analysis was performed to merge all current PK studies of PPF to determine the effects of the CYP2D6 phenotype more accurately on the PPF PK profile. We searched electronic databases for published studies to investigate the association between the PPF PK and CYP2D6 phenotype. Four PK-related outcomes were included: area under the time–concentration curve (AUC), maximum concentration (Cmax), apparent clearance (CL/F), and half-life (t1/2). A total of five studies were included in this meta-analysis (n = 56). Analyses were performed to compare PK parameters between poor metabolizers (PMs) versus extensive metabolizers (EMs). PPF has a non-linear pharmacokinetics; therefore, analyses were performed according to dose (300 mg and 400 mg). At 300 mg, the AUC mean (95% CI), Cmax, and t1/2 of PPF in PMs were 15.9 (12.5–19.2) µg·h/mL, 1.10 (0.796–1.40) µg/mL, and 12.8 (11.3–14.3) h, respectively; these values were 2.4-, 11.2-, and 4.7-fold higher than those in the EM group, respectively. At 400 mg, a comparison was performed between S- and R-enantiomers. The CL/F was approximately 1.4-fold higher for the R-form compared with the S-form, which was a significant difference. This study demonstrated that CYP2D6 metabolizer status could significantly affect the PPF PK profile. Adjusting the dose of PPF according to CYP2D6 phenotype would help to avoid adverse effects and ensure treatment efficacy.
Collapse
Affiliation(s)
- Quyen Thi Tran
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea;
| | - In-hwan Baek
- College of Pharmacy, Kyungsung University, Busan 48434, Korea;
| | - Na-young Han
- College of Pharmacy, Jeju National University, Jeju 63243, Korea;
| | - Hwi-yeol Yun
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea;
- Bio-AI Convergence Research Center, Chungnam National University, Daejeon 34134, Korea
- Correspondence: (H.-y.Y.); (J.-w.C.); Tel.: +82-42-821-5941 or +82-10-7454-5825 (H.-y.Y.); +82-42-821-5929 or +82-10-9882-1070 (J.-w.C.)
| | - Jung-woo Chae
- College of Pharmacy, Chungnam National University, Daejeon 34134, Korea;
- Bio-AI Convergence Research Center, Chungnam National University, Daejeon 34134, Korea
- Correspondence: (H.-y.Y.); (J.-w.C.); Tel.: +82-42-821-5941 or +82-10-7454-5825 (H.-y.Y.); +82-42-821-5929 or +82-10-9882-1070 (J.-w.C.)
| |
Collapse
|
4
|
Belova EV, Semenova EV, Tverdislov VA. On the Chirality of Drugs and the Structures of Biomacromolecules. Biophysics (Nagoya-shi) 2022. [DOI: 10.1134/s0006350922030034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
5
|
Parker MH, Sanoski CA. Clinical Pearls in Using Antiarrhythmic Drugs in the Outpatient Setting. J Pharm Pract 2015; 29:77-86. [DOI: 10.1177/1933719115615878] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A role for oral antiarrhythmic drugs (AADs) remains in clinical practice for patients with atrial and ventricular arrhythmias in spite of advances in nonpharmacologic therapy. Pharmacists play a vital role in the appropriate use of AAD dosing, administration, adverse effects, interactions, and monitoring. Pharmacists who are involved in providing care to patients with cardiac arrhythmias must remain updated regarding the efficacy and safety of the most commonly used AADs. This review will address key issues for appropriate initiation and maintenance of commonly selected Vaughan-Williams Class Ic and III agents in the outpatient setting.
Collapse
Affiliation(s)
- Mary H. Parker
- Clinical Pharmacy Specialist Pharmacy Service, Clinic Coordinator Ambulatory Care, Durham Veterans Affairs Medical Center, Durham, NC, USA
| | | |
Collapse
|
6
|
Faggioni M, Savio-Galimberti E, Venkataraman R, Hwang HS, Kannankeril PJ, Darbar D, Knollmann BC. Suppression of spontaneous ca elevations prevents atrial fibrillation in calsequestrin 2-null hearts. Circ Arrhythm Electrophysiol 2014; 7:313-20. [PMID: 24493699 DOI: 10.1161/circep.113.000994] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Atrial fibrillation (AF) risk has been associated with leaky ryanodine receptor 2 (RyR2) Ca release channels. Patients with mutations in RyR2 or in the sarcoplasmic reticulum Ca-binding protein calsequestrin 2 (Casq2) display an increased risk for AF. Here, we examine the underlying mechanisms of AF associated with loss of Casq2 and test mechanism-based drug therapy. METHODS AND RESULTS Compared with wild-type Casq2+/+ mice, atrial burst pacing consistently induced atrial flutter or AF in Casq2-/- mice and in isolated Casq2-/- hearts. Atrial optical voltage maps obtained from isolated hearts revealed multiple independent activation sites arising predominantly from the pulmonary vein region. Ca and voltage mapping demonstrated diastolic subthreshold spontaneous Ca elevations (SCaEs) and delayed afterdepolarizations whenever the pacing train failed to induce AF. The dual RyR2 and Na channel inhibitor R-propafenone (3 μmol/L) significantly reduced frequency and amplitude of SCaEs and delayed afterdepolarizations in atrial myocytes and intact atria and prevented induction of AF. In contrast, the S-enantiomer of propafenone, an equipotent Na channel blocker but much weaker RyR2 inhibitor, did not reduce SCaEs and delayed afterdepolarizations and failed to prevent AF. CONCLUSIONS Loss of Casq2 increases risk of AF by promoting regional SCaEs and delayed afterdepolarizations in atrial tissue, which can be prevented by RyR2 inhibition with R-propafenone. Targeting AF caused by leaky RyR2 Ca channels with R-propafenone may be a more mechanism-based approach to treating this common arrhythmia.
Collapse
Affiliation(s)
- Michela Faggioni
- Division of Clinical Pharmacology, Department of Medicine, Division of Cardiology, Department of Medicine, Department of Biomedical Engineering and Physics, and Division of Cardiology, Department of Pediatrics, Vanderbilt University, Nashville, TN; and Department of Cardiovascular Diseases, University of Pisa, Pisa, Italy
| | | | | | | | | | | | | |
Collapse
|
7
|
Abstract
Characterization of the circulating metabolites for a new chemical entity in humans is essential for safety assessment, an understanding of their contributions to pharmacologic activities, and their potential involvement in drug-drug interactions. This review examines the abundance of metabolites relative to the total parent drug [metabolite-to-parent (M/P) ratio] from 125 drugs in relation to their structural and physicochemical characteristics, lipoidal permeability, protein binding, and fractional formation from parent (fm). Our analysis suggests that fm is the major determinant of total drug M/P ratio for amine, alcohol, N- and S-oxide, and carboxylic acid metabolites. Passage from the hepatocyte to systemic circulation does not appear to be limiting owing to the vast majority of metabolites formed being relatively lipid permeable. In some cases, active transport plays an important role in this process (e.g., carboxylic acid metabolites). Differences in total parent drug clearance and metabolite clearance are attenuated by the reduction in lipophilicity introduced by the metabolic step and resultant compensatory changes in unbound clearance and protein binding. A small subclass of these drugs (e.g., terfenadine) is unintentional prodrugs with very high parent drug clearance, resulting in very high M/P ratios. In contrast, arenol metabolites show a more complex relationship with fm due largely to the new metabolic routes (conjugation) available to the metabolite compared with the parent drug molecule. For these metabolites, a more thorough understanding of the elimination clearance of the metabolite is critical to discern the likelihood of whether the phenol will constitute a major circulating metabolite.
Collapse
Affiliation(s)
- Cho-Ming Loi
- Pfizer, Inc., 10646 Science Center Drive, San Diego, CA 92121, USA.
| | | | | |
Collapse
|
8
|
Heijman J, Voigt N, Dobrev D. New directions in antiarrhythmic drug therapy for atrial fibrillation. Future Cardiol 2013; 9:71-88. [DOI: 10.2217/fca.12.78] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and has a significant impact on morbidity and mortality. Current antiarrhythmic drugs for AF suffer from limited safety and efficacy, probably because they were not designed based on specific pathological mechanisms. Recent research has provided important insights into the mechanisms contributing to AF and highlighted several potential novel antiarrhythmic strategies. In this review, we highlight the main pathological mechanisms of AF, discuss traditional and novel aspects of atrial antiarrhythmic drugs in relation to these pathological mechanisms, and present potential novel therapeutic approaches including structure-based modulation of atrial-specific cardiac ion channels, restoring abnormal Ca2+ handling in AF and targeting atrial remodeling.
Collapse
Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
- Division of Experimental Cardiology, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Dobromir Dobrev
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| |
Collapse
|
9
|
β-Blocking Properties of Propafenone in Extensive Oxidisers: A Study on Heart Rate Behaviour during Holter Monitoring. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/bf03259424] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
10
|
Lee YS, Maruyama M, Chang PC, Park HW, Rhee KS, Hsieh YC, Hsueh CH, Shen C, Lin SF, Hwang HS, Yin H, Knollmann BC, Chen PS. Ryanodine receptor inhibition potentiates the activity of Na channel blockers against spontaneous calcium elevations and delayed afterdepolarizations in Langendorff-perfused rabbit ventricles. Heart Rhythm 2012; 9:1125-32. [PMID: 22387372 DOI: 10.1016/j.hrthm.2012.02.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Indexed: 01/06/2023]
Abstract
BACKGROUND Na channel blockers are effective in suppressing delayed afterdepolarizations (DADs) in isolated Purkinje fibers. However, in isolated mouse ventricular myocytes lacking calsequestrin, only those Na channel blockers that also inhibit type 2 ryanodine receptor channels were effective against spontaneous Ca elevation (SCaE) and DADs. OBJECTIVE To test the hypothesis that combined Na channel and type 2 ryanodine receptor channel blocker ((R)-propafenone) is more effective than a Na channel blocker (lidocaine) in suppressing SCaE and DADs in the intact rabbit ventricles. METHODS We compared (R)-propafenone (3 μmol/L) with lidocaine (50 μmol/L) on SCaE and DADs by using epicardial optical mapping of intracellular calcium (Ca(i)) and membrane voltage in Langendorff-perfused rabbit hearts. SCaE and DADs were induced by rapid pacing trains and isoproterenol (0.3 μmol/L) infusion. One arbitrary unit is equivalent to the Ca transient amplitude of paced beats. RESULTS SCaEs were observed at the cessation of rapid pacing in all hearts at baseline. (R)-Propafenone nearly completely inhibited DADs and SCaE (0.04 arbitrary units [95% confidence interval 0.02-0.06] vs 0.23 arbitrary units [95% confidence interval 0.18-0.28] at baseline; n = 6 hearts; P <.001). Lidocaine also significantly reduced the SCaE but was significantly (P <.05) less effective than (R)-propafenone. Both drugs increased the rise time of action potential upstroke and reduced conduction velocity to a similar extent, suggesting a significant inhibition of I(Na). CONCLUSIONS Both Na channel blockers significantly reduced tachycardia-induced SCaEs in the rabbit ventricles, but (R)-propafenone was significantly more effective than lidocaine. These data suggest that type 2 ryanodine receptor inhibition potentiates the activity of Na channel blockers against SCaE and DADs in the intact hearts.
Collapse
Affiliation(s)
- Young Soo Lee
- Department of Medicine, Krannert Institute of Cardiology and Division of Cardiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Hwang HS, Hasdemir C, Laver D, Mehra D, Turhan K, Faggioni M, Yin H, Knollmann BC. Inhibition of cardiac Ca2+ release channels (RyR2) determines efficacy of class I antiarrhythmic drugs in catecholaminergic polymorphic ventricular tachycardia. Circ Arrhythm Electrophysiol 2011; 4:128-35. [PMID: 21270101 DOI: 10.1161/circep.110.959916] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Catecholaminergic polymorphic ventricular tachycardia (CPVT) is caused by mutations in the cardiac ryanodine receptor (RyR2) or calsequestrin (Casq2) and can be difficult to treat. The class Ic antiarrhythmic drug flecainide blocks RyR2 channels and prevents CPVT in mice and humans. It is not known whether other class I antiarrhythmic drugs also block RyR2 channels and to what extent RyR2 channel inhibition contributes to antiarrhythmic efficacy in CPVT. METHODS AND RESULTS We first measured the effect of all class I antiarrhythmic drugs marketed in the United States (quinidine, procainamide, disopyramide, lidocaine, mexiletine, flecainide, and propafenone) on single RyR2 channels incorporated into lipid bilayers. Only flecainide and propafenone inhibited RyR2 channels, with the S-enantiomer of propafenone having a significantly lower potency than R-propafenone or flecainide. In Casq2(-/-) myocytes, the propafenone enantiomers and flecainide significantly reduced arrhythmogenic Ca(2+) waves at clinically relevant concentrations, whereas Na(+) channel inhibitors without RyR2 blocking properties did not. In Casq2(-/-) mice, 5 mg/kg R-propafenone or 20 mg/kg S-propafenone prevented exercise-induced CPVT, whereas procainamide (20 mg/kg) or lidocaine (20 mg/kg) were ineffective (n=5 to 9 mice, P<0.05). QRS duration was not significantly different, indicating a similar degree of Na(+) channel inhibition. Clinically, propafenone (900 mg/d) prevented ICD shocks in a 22-year-old CPVT patient who had been refractory to maximal standard drug therapy and bilateral stellate ganglionectomy. CONCLUSIONS RyR2 cardiac Ca(2+) release channel inhibition appears to determine efficacy of class I drugs for the prevention of CPVT in Casq2(-/-) mice. Propafenone may be an alternative to flecainide for CPVT patients symptomatic on β-blockers.
Collapse
Affiliation(s)
- Hyun Seok Hwang
- Oates Institute for Experimental Therapeutics, Vanderbilt University School of Medicine, Division of Clinical Pharmacology, Nashville, TN 37232-0575, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Grilo LS, Carrupt PA, Abriel H. Stereoselective Inhibition of the hERG1 Potassium Channel. Front Pharmacol 2010; 1:137. [PMID: 21833176 PMCID: PMC3153011 DOI: 10.3389/fphar.2010.00137] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 11/03/2010] [Indexed: 12/11/2022] Open
Abstract
A growing number of drugs have been shown to prolong cardiac repolarization, predisposing individuals to life-threatening ventricular arrhythmias known as Torsades de Pointes. Most of these drugs are known to interfere with the human ether à-gogo related gene 1 (hERG1) channel, whose current is one of the main determinants of action potential duration. Prolonged repolarization is reflected by lengthening of the QT interval of the electrocardiogram, as seen in the suitably named drug-induced long QT syndrome. Chirality (presence of an asymmetric atom) is a common feature of marketed drugs, which can therefore exist in at least two enantiomers with distinct three-dimensional structures and possibly distinct biological fates. Both the pharmacokinetic and pharmacodynamic properties can differ between enantiomers, as well as also between individuals who take the drug due to metabolic polymorphisms. Despite the large number of reports about drugs reducing the hERG1 current, potential stereoselective contributions have only been scarcely investigated. In this review, we present a non-exhaustive list of clinically important molecules which display chiral toxicity that may be related to hERG1-blocking properties. We particularly focus on methadone cardiotoxicity, which illustrates the importance of the stereoselective effect of drug chirality as well as individual variations resulting from pharmacogenetics. Furthermore, it seems likely that, during drug development, consideration of chirality in lead optimization and systematic assessment of the hERG1 current block with all enantiomers could contribute to the reduction of the risk of drug-induced LQTS.
Collapse
Affiliation(s)
- Liliana Sintra Grilo
- School of Pharmaceutical Sciences, University of Geneva, University of LausanneGeneva, Switzerland
- Department of Clinical Research, University of BernBern, Switzerland
| | - Pierre-Alain Carrupt
- School of Pharmaceutical Sciences, University of Geneva, University of LausanneGeneva, Switzerland
| | - Hugues Abriel
- Department of Clinical Research, University of BernBern, Switzerland
| |
Collapse
|
13
|
Xie S, Zeng S. Stereoselective Glucuronidation of Propafenone and Its Analogues by Human Recombinant UGT1A9. Chem Pharm Bull (Tokyo) 2010; 58:879-83. [DOI: 10.1248/cpb.58.879] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Shenggu Xie
- Zhejiang Institute of Food and Drug Control
- Department of Pharmaceutical Analysis and Drug Metabolism, College of Pharmaceutical Sciences, Zhejiang University
| | - Su Zeng
- Department of Pharmaceutical Analysis and Drug Metabolism, College of Pharmaceutical Sciences, Zhejiang University
| |
Collapse
|
14
|
Lamprecht G, Stoschitzky K. Enantioselective analysis of R- and S-propafenone in plasma by HPLC applying column switching and liquid–liquid extraction. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:3489-94. [DOI: 10.1016/j.jchromb.2009.08.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/25/2009] [Accepted: 08/12/2009] [Indexed: 11/29/2022]
|
15
|
Affiliation(s)
- Shu-Feng Zhou
- Discipline of Chinese Medicine, School of Health Sciences, RMIT University, Victoria, Australia.
| |
Collapse
|
16
|
Zhou SF, Liu JP, Chowbay B. Polymorphism of human cytochrome P450 enzymes and its clinical impact. Drug Metab Rev 2009; 41:89-295. [PMID: 19514967 DOI: 10.1080/03602530902843483] [Citation(s) in RCA: 502] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.
Collapse
Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Bundoora, Victoria, Australia.
| | | | | |
Collapse
|
17
|
TURGEON JACQUES, MURRAY KATHERINET, RODEN DANM. Effects of Drug Metabolism, Metabolites, and Stereoselectivity on Antiarrhythmic Drug Action. J Cardiovasc Electrophysiol 2008. [DOI: 10.1111/j.1540-8167.1990.tb01065.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
18
|
Abstract
Many chiral drugs are used as their racemic mixtures in clinical practice. Two enantiomers of a chiral drug generally differ in pharmacodynamic and/or pharmacokinetic properties as a consequence of the stereoselective interaction with optically active biological macromolecules. Thus, a stereospecific assay to discriminate between enantiomers is required in order to relate plasma concentrations to pharmacological effect of a chiral drug. Stereoselective metabolism of drugs is most commonly the major contributing factor to stereoselectivity in pharmacokinetics. Metabolizing enzymes often display a preference for one enantiomer of a chiral drug over the other, resulting in enantioselectivity. The structural characteristics of enzymes dictate the enantiomeric discrimination associated with the metabolism of chiral drugs. The stereoselectivity can, therefore, be viewed as the physical property characteristic that phenotypes the enzyme. This review provides a comprehensive appraisal of stereochemical aspects of drug metabolism (i.e., enantioselective metabolism and first-pass effect, enzyme-selective inhibition or induction and drug interaction, species differences and polymorphic metabolism).
Collapse
Affiliation(s)
- Hong Lu
- GlaxoSmithKline, Worldwide Drug Metabolism and Pharmacokinetics, 5 Moore Drive, Research Triangle Park, NC 27709-3398, USA.
| |
Collapse
|
19
|
Brocks DR. Drug disposition in three dimensions: an update on stereoselectivity in pharmacokinetics. Biopharm Drug Dispos 2007; 27:387-406. [PMID: 16944450 DOI: 10.1002/bdd.517] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Many marketed drugs are chiral and are administered as the racemate, a 50:50 combination of two enantiomers. Pharmacodynamic and pharmacokinetic differences between enantiomers are well documented. Because of enantioselectivity in pharmacokinetics, results of in vitro pharmacodynamic studies involving enantiomers may differ from those in vivo where pharmacokinetic processes will proceed. With respect to pharmacokinetics, disparate plasma concentration vs time curves of enantiomers may result from the pharmacokinetic processes proceeding at different rates for the two enantiomers. At their foundation, pharmacokinetic processes may be enantioselective at the levels of drug absorption, distribution, metabolism and excretion. In some circumstances, one enantiomer can be chemically or biochemically inverted to its antipode in a unidirectional or bidirectional manner. Genetic consideration such as polymorphic drug metabolism and gender, and patient factors such as age, disease state and concomitant drug intake can all play a role in determining the relative plasma concentrations of the enantiomers of a racemic drug. The use of a nonstereoselective assay method for a racemic compound can lead to difficulties in interpretation of data from, for example, bioequivalence or dose/concentration vs effect assessments. In this review data from a number of representative studies involving pharmacokinetics of chiral drugs are presented and discussed.
Collapse
Affiliation(s)
- Dion R Brocks
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada.
| |
Collapse
|
20
|
Gardiner SJ, Begg EJ. Pharmacogenetics, drug-metabolizing enzymes, and clinical practice. Pharmacol Rev 2006; 58:521-90. [PMID: 16968950 DOI: 10.1124/pr.58.3.6] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The application of pharmacogenetics holds great promise for individualized therapy. However, it has little clinical reality at present, despite many claims. The main problem is that the evidence base supporting genetic testing before therapy is weak. The pharmacology of the drugs subject to inherited variability in metabolism is often complex. Few have simple or single pathways of elimination. Some have active metabolites or enantiomers with different activities and pathways of elimination. Drug dosing is likely to be influenced only if the aggregate molar activity of all active moieties at the site of action is predictably affected by genotype or phenotype. Variation in drug concentration must be significant enough to provide "signal" over and above normal variation, and there must be a genuine concentration-effect relationship. The therapeutic index of the drug will also influence test utility. After considering all of these factors, the benefits of prospective testing need to be weighed against the costs and against other endpoints of effect. It is not surprising that few drugs satisfy these requirements. Drugs (and enzymes) for which there is a reasonable evidence base supporting genotyping or phenotyping include suxamethonium/mivacurium (butyrylcholinesterase), and azathioprine/6-mercaptopurine (thiopurine methyltransferase). Drugs for which there is a potential case for prospective testing include warfarin (CYP2C9), perhexiline (CYP2D6), and perhaps the proton pump inhibitors (CYP2C19). No other drugs have an evidence base that is sufficient to justify prospective testing at present, although some warrant further evaluation. In this review we summarize the current evidence base for pharmacogenetics in relation to drug-metabolizing enzymes.
Collapse
Affiliation(s)
- Sharon J Gardiner
- Department of Medicine, Christchurch School of Medicine, Private Bag 4345, Christchurch, New Zealand.
| | | |
Collapse
|
21
|
Afshar M, Thormann W. Capillary electrophoretic investigation of the enantioselective metabolism of propafenone by human cytochrome P-450 SUPERSOMES: Evidence for atypical kinetics by CYP2D6 and CYP3A4. Electrophoresis 2006; 27:1526-36. [PMID: 16609933 DOI: 10.1002/elps.200500664] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An enantioselective CE method was used to identify the ability of CYP450 enzymes and their stereoselectivity in catalyzing the transformation of propafenone (PPF) to 5-hydroxy-propafenone (5OH-PPF) and N-despropyl-propafenone (NOR-PPF). Using in vitro incubations with single CYP450 enzymes (SUPERSOMES), 5OH-PPF is shown to be selectively produced by CYP2D6 and N-dealkylation is demonstrated to be mediated by CYP2D6, CYP3A4, CYP1A2, and CYP1A1. For the elucidation of kinetic aspects of the metabolism with CYP2D6 and CYP3A4, incubations with individual PPF enantiomers and racemic PPF were investigated. With the exception of the dealkylation in presence of R-PPF only, which can be described by the Michaelis-Menten model, all CYP2D6-induced reactions were found to follow autoactivation kinetics. For CYP3A4, all NOR-PPF enantiomer formation rates as function of PPF enantiomer concentration were determined to follow substrate inhibition kinetics. The formation of NOR-PPF by the different enzymes is stereoselective and is reduced significantly when racemic PPF is incubated. Clearance values obtained for CYP3A4 dealkylation are stereoselective whereas those of CYP2D6 hydroxylation are not. This paper reports the first investigation of the PPF hydroxylation and dealkylation kinetics by the CYP2D6 enzyme and represents the first report in which enantioselective CE data provide the complete in vitro kinetics of metabolic steps of a drug.
Collapse
Affiliation(s)
- Minoo Afshar
- Department of Clinical Pharmacology, University of Bern, Bern, Switzerland
| | | |
Collapse
|
22
|
Afshar M, Thormann W. Validated capillary electrophoresis assay for the simultaneous enantioselective determination of propafenone and its major metabolites in biological samples. Electrophoresis 2006; 27:1517-25. [PMID: 16532516 DOI: 10.1002/elps.200500663] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A robust, inexpensive, and fully validated CE method for the simultaneous determination of the enantiomers of propafenone (PPF), 5-hydroxy-propafenone (5OH-PPF) and N-despropyl-propafenone (NOR-PPF) in serum and in in vitro media is described. It is based upon liquid-liquid extraction at alkaline pH followed by analysis of the reconstituted extract by CE in presence of a pH 2.0 running buffer composed of 100 mM sodium phosphate, 19% methanol, and 0.6% highly sulfated beta-CD. For each compound, the S-enantiomers are shown to migrate ahead of their antipodes, and the overall run time is about 30 min. Enantiomer levels between 25 and 1000 ng/mL provide linear calibration graphs, and the LOD for all enantiomers is between 10 and 12 ng/mL. The assay is shown to be suitable for the determination of the enantiomers of PPF and its metabolites in in vitro incubations comprising human liver microsomes or single CYP450 enzymes (SUPERSOMES). Incubations with CYP2D6 SUPERSOMES revealed, for the first time, the simultaneous formation of the enantiomers of 5OH-PPF and NOR-PPF with that enzyme. CE data can be used for the evaluation of the enzymatic N-dealkylation and hydroxylation rates.
Collapse
Affiliation(s)
- Minoo Afshar
- Department of Clinical Pharmacology, University of Bern, Bern, Switzerland
| | | |
Collapse
|
23
|
Bachmakov I, Rekersbrink S, Hofmann U, Eichelbaum M, Fromm MF. Characterisation of (R/S)-propafenone and its metabolites as substrates and inhibitors of P-glycoprotein. Naunyn Schmiedebergs Arch Pharmacol 2005; 371:195-201. [PMID: 15900513 DOI: 10.1007/s00210-005-1025-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Accepted: 01/18/2005] [Indexed: 01/03/2023]
Abstract
Digoxin is a drug with a narrow therapeutic index, which is a substrate of the ATP-dependent efflux pump P-glycoprotein. Increased or decreased digoxin plasma concentrations occur in humans due to the inhibition or induction of this drug transporter in organs with excretory function such as small intestine, liver and kidney. It is well known that serum concentrations of digoxin increase considerably in humans if propafenone is given simultaneously. However, it has not been investigated in detail whether propafenone and its metabolites are substrates and/or inhibitors of human P-glycoprotein. The aim of this study, therefore, was to investigate the P-glycoprotein-mediated transport and inhibition properties of propafenone and its major metabolites 5-hydroxypropafenone and N-desalkylpropafenone in Caco-2 cell monolayers. Inhibition of P-glycoprotein-mediated transport by propafenone and its metabolites was determined using digoxin as a P-glycoprotein substrate. No polarised transport was observed for propafenone and N-desalkylpropafenone in Caco-2 cell monolayers. However, 5-hydroxypropafenone translocation was significantly greater from basal-to-apical compared with apical-to-basal (P(app) basal-apical vs. P(app) apical-basal, 10.21+/-2.63 x 10(-6) vs. 4.34+/-1.84 x 10(-6) cm/s; P<0.01). Moreover, propafenone, 5-hydroxypropafenone and N-desalkylpropafenone inhibited P-glycoprotein-mediated digoxin transport with IC(50) values of 6.8, 19.9, and 21.3 microM, respectively. In summary, whereas propafenone and N-desalkylpropafenone are not substrates of P-glycoprotein, 5-hydroxypropafenone is translocated by human P-glycoprotein across cell monolayers. In addition, propafenone and its two major metabolites 5-hydroxypropafenone and N-desalkylpropafenone are inhibitors of human P-glycoprotein and therefore contribute to the digoxin-propafenone interaction observed in humans.
Collapse
Affiliation(s)
- Iouri Bachmakov
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Fahrstrasse 17, 91054 Erlangen, Germany
| | | | | | | | | |
Collapse
|
24
|
Dorne JLCM, Walton K, Slob W, Renwick AG. Human variability in polymorphic CYP2D6 metabolism: is the kinetic default uncertainty factor adequate? Food Chem Toxicol 2002; 40:1633-56. [PMID: 12176090 DOI: 10.1016/s0278-6915(02)00117-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human variability in the kinetics of CYP2D6 substrates has been quantified using a database of compounds metabolised extensively (>60%) by this polymorphic enzyme. Published pharmacokinetic studies (after oral and intravenous dosing) in non-phenotyped healthy adults, and phenotyped extensive (EMs), intermediate or slow-extensive (SEMs) and poor metabolisers (PMs) have been analysed using data for parameters that relate primarily to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve) and primarily to acute exposure (peak concentration). Similar analyses were performed with the available data for subgroups of the population (age, ethnicity and disease). Interindividual differences in kinetics for markers of oral exposure were large for non-phenotyped individuals and for EMs (coefficients of variation were 67-71% for clearances and 54-63% for C(max)), whereas the intravenous data indicated a lower variability (34-38%). Comparisons between EMs, SEMs and PMs revealed an increase in oral internal dose for SEMs and PMs (ratio compared to EMs=3 and 9-12, respectively) associated with lower variability than that for non-phenotyped individuals (coefficients of variation were 32-38% and 30% for SEMs and PMs, respectively). In relation to the uncertainty factors used for risk assessment, most subgroups would not be covered by the kinetic default of 3.16. CYP2D6-related factors necessary to cover 95-99% of each subpopulation ranged from 2.7 to 4.1 in non-phenotyped healthy adults and EMs to 15-18 in PMs and 22-45 in children. An exponential relationship (R(2)=0.8) was found between the extent of CYP2D6 metabolism and the uncertainty factors. The extent of CYP2D6 involvement in the metabolism of a substrate is critical in the estimation of the CYP2D6-related factor. The 3.16 kinetic default factor would cover PMs for substrates for which CYP2D6 was responsible for up to 25% of the metabolism in EMs.
Collapse
Affiliation(s)
- J L C M Dorne
- Clinical Pharmacology Group, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, Southampton SO16 7PX, UK
| | | | | | | |
Collapse
|
25
|
Mehvar R, Brocks DR, Vakily M. Impact of stereoselectivity on the pharmacokinetics and pharmacodynamics of antiarrhythmic drugs. Clin Pharmacokinet 2002; 41:533-58. [PMID: 12102640 DOI: 10.2165/00003088-200241080-00001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Many antiarrhythmic drugs introduced into the market during the past three decades have a chiral centre in their structure and are marketed as racemates. Most of these agents, including disopyramide, encainide, flecainide, mexiletine, propafenone and tocainide, belong to class I antiarrhythmics, whereas verapamil is a class IV antiarrhythmic agent. Except for encainide and flecainide, there is substantial stereoselectivity in one or more of the pharmacological actions of chiral antiarrhythmics, with the activity of enantiomers differing by as much as 100-fold or more for some of these drugs. The absorption of chiral antiarrhythmics appears to be nonstereoselective. However, their distribution, metabolism and renal excretion usually favour one enantiomer versus the other. In terms of distribution, plasma protein binding is stereoselective for most of these drugs, resulting in up to two-fold differences between the enantiomers in their unbound fractions in plasma and volume of distribution. For disopyramide, stereoselective plasma protein binding is further complicated by nonlinearity in the binding at therapeutic concentrations. Hepatic metabolism plays a significant role in the elimination of these antiarrhythmics, accounting for >90% of the elimination of mexiletine, propafenone and verapamil. Additionally, in most cases, significant stereoselectivity is observed in different pathways of metabolism of these drugs. For some drugs, such as propafenone and verapamil, the stereoselectivity in metabolism is further complicated by nonlinearity in one or more of the metabolic pathways. Further, the metabolism of a number of chiral antiarrhythmics, such as mexiletine, propafenone, encainide and flecainide, cosegregates with debrisoquine/sparteine hydroxylation phenotype. Therefore, it is not surprising that a wide interindividual variability exists in the metabolism of these drugs. Excretion of the unchanged enantiomers in urine is an important pathway for the elimination of disopyramide, flecainide and tocainide. The renal clearances of both disopyramide and flecainide exceed the filtration rate for these drugs, suggesting the involvement of active tubular secretion. However, the stereoselectivity in the renal clearance of these drugs, if any, is minimal. Similarly, there is no stereoselectivity in the renal clearance of tocainide, a drug that undergoes tubular reabsorption in addition to glomerular filtration. Overall, substantial stereoselectivity has been observed in both the pharmacokinetics and pharmacodynamics of chiral antiarrhythmic agents. Because the effects of these drugs are related to their plasma concentrations, this information is of special clinical relevance.
Collapse
Affiliation(s)
- Reza Mehvar
- School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter, Amarillo, TX 79106, USA.
| | | | | |
Collapse
|
26
|
Chankvetadze B, Lomsadze K, Blaschke G. Enantioseparation of antiarrhythmic drugs propafenone and diprafenone, their metabolites and analogs by capillary electrophoresis. J Sep Sci 2001. [DOI: 10.1002/1615-9314(20010901)24:9<795::aid-jssc795>3.0.co;2-v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
27
|
Boni JR, Korth-Bradley JM, Richards LS, Chiang ST, Hicks DR, Benet LZ. Chiral bioequivalence: effect of absorption rate on racemic etodolac. Clin Pharmacokinet 2000; 39:459-69. [PMID: 11192477 DOI: 10.2165/00003088-200039060-00006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
BACKGROUND For many racemic drugs, bioequivalence assessment based on isomer-nonspecific assays is appropriate because enantiomeric area under the concentration-time curve (AUC) exposure ratios are close to unity. Use of nonspecific methods in cases in which the ratio is substantially greater or less than 1, however, may obscure real therapeutic differences among formulations, especially if the enantiomers exhibit differing pharmacological potencies. OBJECTIVE To examine the influence of absorption rate on etodolac bioequivalence as measured by total [(R,S)-] and (S)-etodolac. DESIGN Single dose, 3-period, crossover, pharmacokinetic study in 24 healthy volunteers in which the administration rate of etodolac was varied. METHODS Participants received etodolac 400mg in solution, given as a single dose over 1 minute or as divided doses over 30 and 90 minutes. Unresolved and enantiomer concentrations of etodolac were measured by a validated HPLC assay. The enantiomer ratio was similarly measured by HPLC. RESULTS Bioequivalence parameters derived for both unresolved and (S)etodolac indicate that peak plasma drug concentration (Cmax) was not bioequivalent. By delaying absorption, bioequivalence was lost. CONCLUSIONS Collectively, these data demonstrate that bioequivalence between 2 products of etodolac based on enantiomerically nonspecific criteria alone may not generalise to the pharmacologically relevant (S)-enantiomer. This suggests that enantiospecific assays are necessary for bioequivalence assessments.
Collapse
Affiliation(s)
- J R Boni
- Department of Clinical Pharmacokinetics, Wyeth-Ayerst Research, Radnor, Pennsylvania 19101-1245, USA.
| | | | | | | | | | | |
Collapse
|
28
|
Yao TW, Zhou Q, Zeng S. Stereoselective determination of propafenone enantiomers in transgenic Chinese hamster CHL cells expressing human cytochrome P450. Biomed Chromatogr 2000; 14:498-501. [PMID: 11113932 DOI: 10.1002/1099-0801(200011)14:7<498::aid-bmc9>3.0.co;2-d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
An enantioselective assay for S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450 was developed. The method involved extraction of propafenone from the S9s incubates, and formation of propafenone diastereomeric derivatives with the chiral reagent 2,3,4, 6-tetra-O-beta-D-glucopranosyl isothiocyanate. Separation and quantitation of diastereomeric propafenone derivatives were carried out in a reverse-phase-HPLC system with UV detection. The assay was linear from 2 to 200 microg/mL for each enantiomer. The analytical method gave average recoveries of 97.5% and 97.0% for S(+)- and R(-)-propafenone, respectively. The limits of detection and quantitation for the method are 0.1 and 2.0 microg/mL for both S(+)- and R(-)-propafenone, respectively. The reproducibility of the assay was good (RSD <10%). The method allowed study of the depletion of S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450. The stereoselectivity of propafenone phase I metabolism via cDNA-expressed CYP3A4 was observed.
Collapse
Affiliation(s)
- T W Yao
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310006, People's Republic of China
| | | | | |
Collapse
|
29
|
Bonato PS, de Abreu LR, de Gaitani CM, Lanchote VL, Bertucci C. Enantioselective HPLC analysis of propafenone and of its main metabolites using polysaccharide and protein-based chiral stationary phases. Biomed Chromatogr 2000; 14:227-33. [PMID: 10861733 DOI: 10.1002/1099-0801(200006)14:4<227::aid-bmc971>3.0.co;2-q] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
HPLC on chiral stationary phases has been used for the enantioselective assay of propafenone (PPF), 5-hydroxypropafenone (PPF-50H) and N-despropylpropafenone (PPF-NOR) enantiomers. The results obtained on Chiralpak AD column showed that it is useful for the resolution of PPF and of its main metabolites, although the peaks obtained for PPF-NOR were not symmetrical under the conditions investigated. This column and circular dichroism-based detection system were used to determine the absolute configuration of the eluates. Furthermore, the influence of the mobile phase composition on the resolution of PPF and of its main metabolites was investigated on cellulose derivatives (Chiralcel OD-H and Chiralcel OD-R) and protein (Chiral AGP and Ultron ES-OVM)-based chiral stationary phases. The enantiomers of PPF were resolved on all the columns, except for the Ultron ES-OVM. This column, the Chiralpak AD and the Chiralcel OD-H columns were suitable for the resolution of the PPF-50H enantiomers. The PPF-NOR enantiomers were resolved on the Chiralpak AD, Chiral AGP and Chiralcel OD-R columns.
Collapse
Affiliation(s)
- P S Bonato
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto-USP, Ribeirão Preto, Brazil
| | | | | | | | | |
Collapse
|
30
|
Brockmöller J, Kirchheiner J, Meisel C, Roots I. Pharmacogenetic diagnostics of cytochrome P450 polymorphisms in clinical drug development and in drug treatment. Pharmacogenomics 2000; 1:125-51. [PMID: 11256586 DOI: 10.1517/14622416.1.2.125] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The current use and future perspectives of molecular genetic characterisation of cytochrome P450 enzymes (CYP) for drug development and drug treatment are summarised. CYP genes are highly polymorphic and the enzymes play a key role in the elimination of the majority of drugs from the human body. Frequent variants of some enzymes, CYP2A6, 2C9, 2C19 and 2D6, should be analysed in participants of clinical trials whenever these enzymes may play a role. It is suggested that a CYP genotype certificate is handed out to the volunteers or patients to avoid replicate analyses, and to allow that this information is available for future research and also for treatment with eventually needed drugs. Guidelines on what CYP alleles have to be analysed in drug development, as well as on analytical validation and CYP genotype data handling will be required. Treatment with several drugs may be improved by prior genotyping. The concepts and problems of CYP genotype-based clinical dose recommendations are presented and illustrated for selected drugs. The requirement for prospective trials on the medical and economic benefits of routine CYP genotyping is emphasised. Specific operationally defined recommendations dependent on genotype are a prerequisite for such studies and this review presents tentative CYP genotype-based dose recommendations systematically calculated from published data. Because of the multiplicity of factors involved, these doses will not be the optimal doses for each given individual, but should be more adequate than doses generally recommended for an average total population. Those CYP alleles and polymorphically metabolised drugs which are currently most interesting in drug development and drug treatment are reviewed, and more complete information is available from websites cited in this article.
Collapse
Affiliation(s)
- J Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Charité, Humboldt University, Berlin, Germany.
| | | | | | | |
Collapse
|
31
|
Chen X, Zhong D, Blume H. Stereoselective pharmacokinetics of propafenone and its major metabolites in healthy Chinese volunteers. Eur J Pharm Sci 2000; 10:11-6. [PMID: 10699379 DOI: 10.1016/s0928-0987(99)00083-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The stereoselective pharmacokinetics of propafenone (PPF) and its active metabolite 5-hydroxypropafenone (5-OHP) as well as their glucuronide and sulfate conjugates have been investigated, in order to clarify the relationship between metabolism and stereoselective disposition of PPF in humans. After oral administration of 300 mg racemic PPF hydrochloride to 10 healthy Chinese subjects, the areas under the plasma concentration-time curves (AUCs) for (S)-PPF were significantly higher (S/R ratio, 1.50+/-0.17) and the apparent oral clearance significantly lower (S/R ratio, 0.68+/-0.07) than those parameters for (R)-PPF. In contrast, the AUCs of PPF glucuronide (PPF-G) were lower for (S)-PPF-G than for the (R)-enantiomer (S/R ratio, 0.83+/-0.12). The partial clearance of (S)-PPF by glucuronidation pathway was lower than that of (R)-PPF and the enantiomeric ratio was 0.62+/-0.04. The t(max) values of PPF glucuronide diastereoisomers showed no statistically significant differences between each other, but were much shorter than the corresponding values of the parent drug, implying that glucuronidation may be the 'first-choice' pathway in presystemic metabolism of PPF. Glucuronidation of 5-OHP favored the (S)-enantiomer, whereas the sulfation showed a large preference for the (R)-enantiomer. After beta-glucuronidase hydrolysis, no significant differences were observed in AUCs between 5-OHP enantiomers (including unconjugated and conjugated 5-OHP). The results suggest that the significant difference in disposition between PPF enantiomers may be, at least in part attributed to stereoselective metabolism in the glucuronidation pathway.
Collapse
Affiliation(s)
- X Chen
- Laboratory of Drug Metabolism and Pharmacokinetics, Shenyang Pharmaceutical University, Wenhua Road 103, Shenyang, PR China
| | | | | |
Collapse
|
32
|
Valderrábano M, Singh BN. Electrophysiologic and Antiarrhythmic Effects of Propafenone: Focus on Atrial Fibrillation. J Cardiovasc Pharmacol Ther 1999; 4:183-198. [PMID: 10684540 DOI: 10.1177/107424849900400308] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- M Valderrábano
- Veterans Affairs Medical Center of West Los Angeles, Los Angeles, California, USA
| | | |
Collapse
|
33
|
Pires de Abreu LR, Lanchote VL, Bertucci C, Cesarino EJ, Bonato PS. Simultaneous determination of propafenone and 5-hydroxypropafenone enantiomers in plasma by chromatography on an amylose derived chiral stationary phase. J Pharm Biomed Anal 1999; 20:209-16. [PMID: 10704025 DOI: 10.1016/s0731-7085(99)00022-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
An enantioselective liquid chromatography method was developed for the simultaneous determination of propafenone (PPF) and 5-hydroxypropafenone (PPF-5OH) enantiomers in plasma. After liquid liquid extraction with dichloromethane, the enantiomers were resolved on a Chiralpak AD column using hexane-ethanol (88:12, v/v) plus 0.1% diethylamine as the mobile phase and monitored at 315 nm. Under these conditions the enantiomeric fractions of the drug and of its metabolite were analysed within 20 min. The extraction procedure resulted in absolute recoveries of 62.9 and 61.3% for (R)- and (S)-PPF, respectively, and of 57.6 and 56.5% for (R)- and (S)-PPF-5OH, respectively. This procedure was efficient in removing endogenous interferents as well the interference of an other PPF metabolite, N-despropylpropafenone (PPF-NOR). The calibration curves were linear over the concentration range 25-1250 ng/ml. Low values of the coefficients of variation were demonstrated for both within-day and between day assays. The method described in this paper allows the determination of PPF and PPF-5OH enantiomers at plasma levels as low as 25 ng/ml and can be used in clinical pharmacokinetic studies.
Collapse
|
34
|
Cai WM, Chen B, Cai MH, Chen Y, Zhang YD. The influence of CYP2D6 activity on the kinetics of propafenone enantiomers in Chinese subjects. Br J Clin Pharmacol 1999; 47:553-6. [PMID: 10336580 PMCID: PMC2014184 DOI: 10.1046/j.1365-2125.1999.00932.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To determine role of CYP2D6 activity in the pharmacokinetics of propafenone (PPF) enantiomers in native Chinese subjects. METHODS Sixteen extensive metabolizers (EMs) and one poor metabolizer (PM), whose phenotype had been previously assessed with dextromethorphan metabolic phenotyping, were enrolled. Blood samples (0 approximately 15 h) were taken after oral administration of a single dose (400 mg) of racemic-propafenone hydrochloride. A reverse-phase h.p.l.c. method with pre-column derivatization was employed to quantitate enantiomeric concentrations of propafenone in plasma. RESULTS For the EM subjects, S-PPF was less rapidly metabolized and had higher peak plasma concentrations than R-PPF (413+/-143 vs 291+/-109 ng ml-1, P<0.001). The AUC was markedly higher for S-PPF than for R-PPF (2214+/-776 vs 1639+/-630 microg h l-1, P<0.001), whereas the clearance of S-PPF was significantly lower than that of R-PPF (96.0+/-39.0 vs 138+/-78 l h-1, P<0.01). There were no differences in t1/2, and Cmax between the two isomers (P >0.05). In the one PM subject, not only did S-PPF appear to undergo less rapid metabolism than R-PPF, but the subject also showed 2 approximately 3 fold differences in Cmax, CL and AUC compared with EMs. The correlation coefficients (rs ) between dextromethorphan metabolic ratio (lg MR) and pharmacokinetic parameters (Cmax, CL and AUC) were 0.63, -0.87, 0.87 for S-PPF and 0. 57, -0.73, 0.86 for R-PPF, respectively. CONCLUSIONS Our results suggest that CYP2D6 activity contributes to the pharmacokinetic variability of propafenone enantiomers in Chinese subjects.
Collapse
Affiliation(s)
- W M Cai
- Department of Clinical Pharmacology, Jinling Hospital, Nanjing, China
| | | | | | | | | |
Collapse
|
35
|
Zhong D, Chen X. Enantioselective determination of propafenone and its metabolites in human plasma by liquid chromatography-mass spectrometry. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 721:67-75. [PMID: 10027638 DOI: 10.1016/s0378-4347(98)00444-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A sensitive and stereospecific method was developed to determine propafenone (PPF), 5-hydroxypropafenone (5-OHP) as well as their glucuronide and sulfate conjugates in human plasma. Quantitative analyses and preparative isolations of PPF and 5-OHP were performed on a Nucleosil C18 column after liquid-liquid extraction. Afterwards the enantiomeric ratios of PPF and 5-OHP were determined on a Chiral-AGP column with ion trap mass spectrometric detection in the selected reaction monitoring (SRM) mode via electrospray ionization (ESI). The enantiomers of PPF and 5-OHP were separated with different mobile phases. For PPF enantiomers, the mobile phase consisted of 10 mM ammonium acetate buffer (pH 5.96)-1-propanol (100:9, v/v), at a flow-rate of 0.5 ml/min; And for 5-OHP enantiomers, the mobile phase was 10 mM ammonium acetate buffer (pH 4.1)-2-propanol (100:0.9, v/v), at a flow-rate of 0.6 ml/min. The SRM transitions m/z 342 to m/z 324 and m/z 358 to m/z 340 were monitored for detection of enantiomers of PPF and 5-OHP, respectively. Linear calibration curves were obtained in the concentration range of 20-1600 ng/ml for each enantiomer of PPF and 20-500 ng/ml for the 5-OHP enantiomer. The limits of quantification for each enantiomer of PPF and 5-OHP were found to be 20 ng/ml. Precision and accuracy were within 11% over the calibration range for each of the analytes. Incubation of the plasma samples with beta-glucuronidase/arylsulfatase and the use of the specific beta-glucuronidase inhibitor saccharo-1,4-lactone allows the quantitation of both the glucuronide and sulfate conjugates of the enantiomers. The method was applied to human plasma samples from ten Chinese male volunteers after oral administration of 300 mg racemic propafenone.
Collapse
Affiliation(s)
- D Zhong
- Laboratory of Drug Metabolism and Pharmacokinetics, Shenyang Pharmaceutical University, PR China.
| | | |
Collapse
|
36
|
Li G, Gong PL, Qiu J, Zeng FD, Klotz U. Stereoselective steady state disposition and action of propafenone in Chinese subjects. Br J Clin Pharmacol 1998; 46:441-5. [PMID: 9833596 PMCID: PMC1873699 DOI: 10.1046/j.1365-2125.1998.00806.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [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 the steady state disposition and action of racemic propafenone and its enantiomers and the potential for an enantiomer-enantiomer interaction in Chinese subjects. METHODS Eight healthy male Chinese individuals received in a double-blind, randomized, cross-over study racemic propafenone (150 mg every 6 h), (S)-, and (R)-propafenone (150 mg each every 6 h) and placebo orally for 4 days. During the last dosing interval the plasma concentrations of both enantiomers of propafenone were measured and ECG, blood pressure (MAP) and heart rate were monitored. RESULTS Whereas the apparent elimination half-life (t1/2,z), mean residence time (MRT) and time to reach peak concentrations (tmax) of (S)- and (R)-propafenone were similar and independent of the administered agent, significant differences were observed in the apparent oral clearance (CLO) of the enantiomers. During dosing with racemic propafenone CLO of (S)- and (R)-propafenone averaged (+/-s.d.) 1226+751 and 1678+625 ml min(-1), respectively (P=0.024). Following the administration of the pure enantiomers CLO of (S)-propafenone increased (P= 0.007) to 2028+/-959 ml min(-1) and that of (R)-propafenone was reduced (P= 0.042) to 1318+/-867 ml min(-1). Both enantiomers and the racemate caused about a 10% increase in the QRS duration (P<0.05) and PR-interval (P<0.01) when compared with placebo. The increase in maximum exercise heart rate was significantly (P<0.05) attenuated only at 3 h following the administration of the racemate and the S-enantiomer. MAP and QTC were not affected significantly. CONCLUSIONS These data indicate that the stereoselective disposition of propafenone is similar in Chinese and Caucasian subjects (previously published findings), the (R)-enantiomer being cleared more rapidly. A similar enantiomer-enantiomer interaction also occurred. Thus, when the racemate was given, the elimination of (S)-propafenone was impaired and that of the (R)-form accelerated compared with single enantiomer administration. The results indicate that dosage adjustments are probably not required in Chinese patients receiving propafenone.
Collapse
Affiliation(s)
- G Li
- Department of Clinical Pharmacology, School of Pharmacy, Tongji Medical University, Wuhan/PR China
| | | | | | | | | |
Collapse
|
37
|
de Gaitani CM, Lanchote VL, Bonato PS. Enantioselective analysis of propafenone in plasma using a polysaccharide-based chiral stationary phase under reversed-phase conditions. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1998; 708:177-83. [PMID: 9653960 DOI: 10.1016/s0378-4347(97)00652-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We present a method for the enantioselective analysis of propafenone in human plasma for application in clinical pharmacokinetic studies. Propafenone enantiomers were resolved on a 10-microm Chiralcel OD-R column (250 x 4.6 mm I.D.) after solid-phase extraction using disposable solid-phase extraction tubes (RP-18). The mobile phase used for the resolution of propafenone enantiomers and the internal standard propranolol was 0.25 M sodium perchlorate (pH 4.0)-acetonitrile (60:40, v/v), at a flow-rate of 0.7 ml/min. The method showed a mean recovery of 99.9% for (S)-propafenone and 100.5% for (R)-propafenone, and the coefficients of variation obtained in the precision and accuracy study were below 10%. The proposed method presented quantitation limits of 25 ng/ml and was linear up to a concentration of 5000 ng/ml of each enantiomer.
Collapse
Affiliation(s)
- C M de Gaitani
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto-USP, Ribeirão Preto CEP, Brazil
| | | | | |
Collapse
|
38
|
Islam MR, Mahdi JG, Bowen ID. Pharmacological importance of stereochemical resolution of enantiomeric drugs. Drug Saf 1997; 17:149-65. [PMID: 9306051 DOI: 10.2165/00002018-199717030-00002] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Drug enantiomers have identical properties in an achiral environment, but should be considered as different chemical compounds. This is because they often differ considerably in potency, pharmacological activity and pharmacokinetic profile, since the modules with which they interact in biological systems are also optically active. Within biological systems, the metabolism of one isomer may be via a different pathway or occur at a different rate from that of the other isomer. Preferential binding of one isomer to plasma proteins may cause differences in circulating free drug and hence alter concentrations at active sites. Interactions of both isomers may differ at the active sites through which pharmacological action is mediated. Actions and levels of activity of the stereoisomers in vivo may also differ. All the pharmacological activity may reside in a single enantiomer, whereas several possibilities exist for the other enantiomer-- it may be inactive, have a qualitatively different effect, an antagonistic effect or produce greater toxicity. Two isomers may have nearly identical qualitative pharmacological activity, qualitatively similar pharmacological activity but quantitatively different potency, or qualitatively different pharmacological activity. To avoid adverse effects and optimise the therapeutic value of enantiomeric drugs, it is necessary that methods for the resolution of racemates be evolved and devolved to determine isomeric purity, establish the effectiveness of isomers of the drug, and detect the presence of an enantiomer with lower therapeutic activity and undesirable adverse effects. Even if a drug is given as a pure enantiomer, methods to discriminate between enantiomers are required because racemisation can occur both in vitro and in vivo. Methods developed for resolution of drug enantiomers should facilitate routine testing of single isomers and their metabolites, studies of pharmacological, toxicological and clinical effectiveness, routine analysis of racemates, pure enantiomers or intermediates in manufacturing processes, and investigation of the potential for inversion of an enantiopure drug substance during the early stages of drug development and therapeutic drug monitoring.
Collapse
Affiliation(s)
- M R Islam
- School of Pure and Applied Biology, University of Wales College of Cardiff, UK
| | | | | |
Collapse
|
39
|
Kroemer HK, Fromm MF, Eichelbaum M. Stereoselectivity in drug metabolism and action: effects of enzyme inhibition and induction. Ther Drug Monit 1996; 18:388-92. [PMID: 8857556 DOI: 10.1097/00007691-199608000-00013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Many synthetic drugs that contain a chiral center are marketed as racemates. Taking into account the composite nature of chiral rugs has improved our understanding of the dose/effect relationship of these compounds. It is widely accepted that drug metabolism is often responsible for stereoselective disposition and hence factors modulating the activity of drug-metabolizing enzymes can modify this effect. The present article highlights the influence of some of these factors (induction and inhibition of drug-metabolizing enzymes) on stereoselective drug disposition. The latter topic includes an enantiomer/enantiomer interaction that alters drug disposition and drug action.
Collapse
Affiliation(s)
- H K Kroemer
- Dr. Margarete Fischer-Bosch-Institut für Klinische Pharmakologie, Stuttgart, Germany
| | | | | |
Collapse
|
40
|
Marzo A, Balant LP. Investigation of xenobiotic metabolism by CYP2D6 and CYP2C19: importance of enantioselective analytical methods. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 678:73-92. [PMID: 8861658 DOI: 10.1016/0378-4347(95)00229-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Investigations into the genetic polymorphism of drug metabolism have involved specific models to screen poor and extensive metabolisers of xenobiotics. Debrisoquine, sparteine, S-mephenytoin and dextromethorphan are particularly well known. They have been extensively described in the literature and are used to phenotype human subjects before performing investigations with new drugs which are believed to be under the control of a genetic polymorphism. Dextromethorphan, debrisoquine and sparteine are good substrates for CYP2D6, whereas the S-enantiomer of mephenytoin is a good substrate for CYP2C19, both being two isozymes of cytochrome P-450. In many drugs, the hepatic microsomal oxidative metabolism involving stereogenic centres congregates either with CYP2D6 or with CYP2C19 or, in certain cases, with both of them. The availability of both CYP2D6 from poor and extensive metabolisers and an enantioselective assay would allow genetic polymorphism in drug biotransformation to be investigated in vitro ex vivo at an early stage of drug development before the IND (investigational new drug). Single-dose investigations in vivo can also be performed when only minimal pre-clinical toxicological data are available and produce more reliable results than in vitro studies. This paper focuses on the problem of genetic polymorphism in drug development and specifically discusses some relevant knowledge gained in the last two decades on enantioselective bioassays. Specific examples are given.
Collapse
Affiliation(s)
- A Marzo
- I.P.A.S.S.A., Clinical Pharmacology Department, Stabio, Switzerland
| | | |
Collapse
|
41
|
Eichelbaum M, Gross AS. Stereochemical aspects of drug action and disposition. ADVANCES IN DRUG RESEARCH 1996. [DOI: 10.1016/s0065-2490(96)80003-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
42
|
Mörike K, Magadum S, Mettang T, Griese EU, Machleidt C, Kuhlmann U. Propafenone in a usual dose produces severe side-effects: the impact of genetically determined metabolic status on drug therapy. J Intern Med 1995; 238:469-72. [PMID: 7595187 DOI: 10.1111/j.1365-2796.1995.tb01225.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report the case of an elderly lady presenting with dizziness, a head injury resulting from a fall and bradycardia. Propafenone 150 mg t.i.d. had been prescribed for atrial fibrillation with tachyarrhythmia, induced by hyperthyroidism, 18 months earlier. A toxic concentration of parent propafenone, and no 5-hydroxy metabolite, was detected in a plasma sample. Symptoms disappeared after the discontinuation of propafenone. The poor metaboliser (PM) phenotype of sparteine/debrisoquine was assumed and subsequently confirmed by phenotyping (sparteine test) and genotyping (allele-specific polymerase chain reaction). The PM phenotype is common in European populations, with a prevalence of about 7%. If drugs with narrow therapeutic ranges undergo genetically polymorphic metabolism, toxicity may arise even with recommended doses. Individualization of doses is required to avoid adverse effects.
Collapse
Affiliation(s)
- K Mörike
- Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
Over the past 15 years stereoselectivity has become a well-recognized consideration in clinical pharmacology. Drugs that have an asymmetric center or plane of symmetry within their molecular structure are said to be chiral. They are available as pairs of nonsuperimposable mirror images, called enantiomers, that share essentially the same physicochemical properties. These three-dimensional structural differences, however, can translate into enantiospecific pharmacologic or pharmacokinetic properties, which may be important in understanding the clinical pharmacology of chiral drugs. Most chiral drugs are available as the racemate, in which equal proportions of the two enantiomers are administered concurrently. The pharmacologic and disposition properties of many chiral drugs are documented to be stereospecific, and this has influenced the regulatory requirements for the approval of new drug candidates. Due to this influence on new drug development, the possible issues surrounding racemic drugs will undoubtedly affect the types of pharmaceuticals that are used clinically in the next century. Accordingly, considerable advances have been made in producing optically pure drug. It should be emphasized, however, that stereochemically pure drugs are not necessarily superior to the respective racemates.
Collapse
Affiliation(s)
- D R Brocks
- SmithKline Beecham Pharmaceutical Research and Development, King of Prussia, Pennsylvania, USA
| | | |
Collapse
|
44
|
Chu KM, Shieh SM, Hu OY. Pharmacokinetics and pharmacodynamics of enantiomers of pimobendan in patients with dilated cardiomyopathy and congestive heart failure after single and repeated oral dosing. Clin Pharmacol Ther 1995; 57:610-21. [PMID: 7781260 DOI: 10.1016/0009-9236(95)90223-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pharmacokinetics and pharmacodynamics of pimobendan were studied in eight patients with dilated cardiomyopathy and chronic congestive heart failure after single dosing and after 2-week repeated dosing of 5 mg racemic pimobendan. Enantiomers of pimobendan and its demethylated metabolite in plasma and in red blood cells were measured. In the single-dose study, the peak plasma levels of 16.3 +/- 4.0 and 17.0 +/- 3.1 ng/ml of (+)- and (-)-pimobendan were observed at 0.9 hour after dosing. The concentration-time curves followed a two-compartment model, with terminal half-lives of 2.56 +/- 0.35 and 2.93 +/- 0.33 hours for (+)- and (-)-pimobendan (p > 0.05), respectively. The oral volumes of distribution after equilibrium were 3.26 +/- 0.74 and 3.13 +/- 0.75 L/kg, and oral clearances were 28.6 +/- 7.0 and 21.9 +/- 4.1 ml/min/kg for (+)- and (-)-pimobendan (p > 0.05), respectively. In red blood cells, the respective (+)- and (-)-pimobendan concentrations were 5.8 and 8.4 times higher than those in plasma, indicating a stereoselective partitioning of drugs between plasma and red blood cells. The pharmacodynamic effect of pimobendan was evaluated by echocardiography. The ejection fraction, mean velocity of circumferential fiber shortening, aortic flow peak velocity, cardiac index, and stroke volume index significantly increased 50% to 60%. The left ventricular end-systolic dimension, systolic blood pressure, and diastolic blood pressure significantly decreased 8% to 11%. These effects lasted for more than 8 hours. In a 2-week repeated-dose study, there was no significant dose accumulation in plasma and red blood cells. The pharmacokinetic parameters were similar to those in the single-dose study, except for significantly shorter absorption half-lives. The baseline levels of cardiac index and stroke volume index were significantly higher than the baseline levels in the single-dose study. This suggests an accumulation of pharmacodynamic effects despite a relatively short elimination half-life.
Collapse
Affiliation(s)
- K M Chu
- Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan, Republic of China
| | | | | |
Collapse
|
45
|
Abstract
OBJECTIVE To describe how drug stereoisomers may differ in pharmacokinetic and pharmacodynamic properties and how these differences may affect therapeutic outcomes. STUDY SELECTION Representative studies were chosen from the drug literature demonstrating stereoisomeric differences in drug absorption, protein binding and distribution, metabolism, and elimination. Furthermore, examples of pharmacodynamic differences between drug stereoisomers are presented to demonstrate that these stereoisomers not only may differ in pharmacologic potency, but may possess entirely different pharmacologic actions. DATA SYNTHESIS Examples are presented demonstrating that when stereoiosomeric differences in pharmacokinetics are linked to pharmacodynamic differences, alterations in therapeutic effect can result. Additionally, drug interactions are discussed in which 1 isomer is affected to a greater extent than the other, potentially causing not only an increase or decrease in effect, but also a change in pharmacologic action. Examples also are presented of the marketing of single isomer entities, with a discussion of the use of these products. Finally, preliminary policies of the Food and Drug Administration are discussed, as well as the potential implications of these policies. CONCLUSIONS Drugs that are administered as stereoisomers can differ with respect to both pharmacokinetics and pharmacodynamics, and these differences may have profound implications in pharmacotherapy. All future investigations of drugs that exist as stereoisomers must take into account the pharmacokinetics and pharmacodynamics of both isomers to understand fully the observed phenomena.
Collapse
Affiliation(s)
- T S Tracy
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, USA
| |
Collapse
|
46
|
Groschner K, Lindner W, Schnedl H, Kukovetz WR. The effects of the stereoisomers of propafenone and diprafenone in guinea-pig heart. Br J Pharmacol 1995; 102:669-74. [PMID: 1364837 PMCID: PMC1917929 DOI: 10.1111/j.1476-5381.1991.tb12231.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. Optically pure enantiomers of propafenone and diprafenone were prepared from their racemic mixtures and tested for their ability to block beta-adrenoceptors and to prolong functional refractory period in the guinea-pig heart. beta-Adrenoceptor affinity of the enantiomers was determined by the radioligand binding technique and in functional experiments. 2. Propafenone and diprafenone inhibited specific binding of the beta-adrenoceptor antagonist (-)-[3H]-CGP-12177 to guinea-pig myocardial membranes. beta-Adrenoceptor affinities of diprafenone enantiomers exceeded those of corresponding propafenone enantiomers by one order of magnitude. Displacement of (-)-[3H]-CGP-12177 by both antiarrhythmics was highly stereoselective, in that the (S)-enantiomers were 40-60 fold, i.e. 1.6-1.8 log units more potent than the (R)-enantiomers. 3. Propafenone and diprafenone antagonized the positive inotropic action of isoprenaline in isolated atria. beta-Adrenoceptor antagonist potencies of diprafenone enantiomers were about one order of magnitude higher than those of corresponding propafenone enantiomers. For both drugs the (S)-enantiomer was found to be considerably more potent (14-40 fold) than the (R)-enantiomer. 4. Propafenone and diprafenone prolonged functional refractory period of isolated auricles with equal potency and no difference in the antiarrhythmic activity of purified enantiomers was found. 5. It is concluded that the enantiomers of propafenone and diprafenone exert comparable antiarrhythmic activity, whereas only (S)-enantiomers block cardiac beta-adrenoceptors with high affinity, which explains the beta-adrenoceptor antagonist effects of the racemic drugs.
Collapse
Affiliation(s)
- K Groschner
- Institut für Pharmakodynamik und Toxikologie, Karl-Franzens-Universität Graz, Austria
| | | | | | | |
Collapse
|
47
|
Blume H, Zhong D, Elze M, Wendt G, Schug B, Scheidel B, Hutt HJ, Hagenlocher M. Advantages of a steady-state crossover design in assessment of bioequivalence of highly variable drugs: propafenone. Eur J Pharm Sci 1994. [DOI: 10.1016/0928-0987(94)00068-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
48
|
Soltés L, Sébille B, Szalay P. Propafenone binding interaction with human alpha 1-acid glycoprotein: assessing experimental design and data evaluation. J Pharm Biomed Anal 1994; 12:1295-302. [PMID: 7841226 DOI: 10.1016/0731-7085(94)00074-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Binding data on racemic RS-propafenone as well as individual R- and S-drug enantiomers interacting reversibly with human alpha 1-acid glycoprotein, as obtained by a high-performance liquid chromatographic method, are evaluated according to three different approaches introduced, respectively, by Scatchard, Bjerrum, and by Tobler and Engel. A non-linear curve-fitting procedure was applied to compute the binding parameters exclusively for the binary system comprising the examined protein and R- and S-propafenone, individually. The exactness of the study design rather than the numerical values were the focus of attention in the evaluation of the data found.
Collapse
Affiliation(s)
- L Soltés
- Institute of Experimental Pharmacology, Slovak Academy of Sciences, Bratislava
| | | | | |
Collapse
|
49
|
Abstract
Genetic polymorphisms of drug metabolizing enzymes are well recognized. This review presents molecular mechanisms, ontogeny and clinical implications of genetically determined intersubject variation in some of these enzymes. Included are the polymorphic enzymes N-acetyl transferase, cytochromes P4502D6 and 2C, which have been well described in humans. Information regarding other Phase I and Phase II polymorphic pathways, such as glutathione and methyl conjugation and alcohol and acetaldehyde oxidation continues to increase and are also discussed. Genetic factors effecting enzyme activity are frequently important determinants of the disposition of drugs and their efficacy and toxicity. In addition, associations between genetic differences in these enzymes and susceptibility to carcinogens and teratogens have been reported. Ultimately, the application of knowledge regarding these genetic factors of enzyme activity may guide medical therapy and minimize xenobiotic-induced disease.
Collapse
Affiliation(s)
- D G May
- Department of Pediatrics, Wayne State University, Children's Hospital of Michigan, Detroit 48201
| |
Collapse
|
50
|
Abstract
Individual variation in pharmacokinetics has long been recognised. This variability is extremely pronounced in drugs that undergo extensive first-pass metabolism. Drug concentrations obtained from individuals given the same dose could range several-fold, even in young healthy volunteers. In addition to the liver, which is the major organ for drug and xenobiotic metabolism, the gut and the lung can contribute significantly to variability in first-pass metabolism. Unfortunately, the contributions of the latter 2 organs are difficult to quantify because conventional in vivo methods for quantifying first-pass metabolism are not sufficiently specific. Drugs that are mainly eliminated by phase II metabolism (e.g. estrogens and progestogens, morphine, etc.) undergo significant first-pass gut metabolism. This is because the gut is rich in conjugating enzymes. The role of the lung in first-pass metabolism is not clear, although it is quite avid in binding basic drugs such as lidocaine (lignocaine), propranolol, etc. Factors such as age, gender, disease states, enzyme induction and inhibition, genetic polymorphism and food effects have been implicated in causing variability in pharmacokinetics of drugs that undergo extensive first-pass metabolism. Of various factors considered, age and gender make the least evident contributions, whereas genetic polymorphism, enzymatic changes due to induction or inhibition, and the effects of food are major contributors to the variability in first-pass metabolism. These factors can easily cause several-fold variations. Polymorphic disposition of imipramine and propafenone, an increase in verapamil first-pass metabolism by rifampicin (rifampin), and the effects of food on propranolol, metoprolol and propafenone, are typical examples. Unfortunately, the contributions of these factors towards variability are unpredictable and tend to be drug-dependent. A change in steady-state clearance of a drug can sometimes be exacerbated when first-pass metabolism and systemic clearance of a drug are simultaneously altered. Therefore, an understanding of the source of variability is the key to the optimisation of therapy.
Collapse
Affiliation(s)
- Y K Tam
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada
| |
Collapse
|