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Drug Interaction Studies (drug + interaction_studies)
Selected AbstractsPregabalin Drug Interaction Studies: Lack of Effect on the Pharmacokinetics of Carbamazepine, Phenytoin, Lamotrigine, and Valproate in Patients with Partial EpilepsyEPILEPSIA, Issue 9 2005Martin J. Brodie Summary:,Purpose: Pregabalin (PGB) is an ,2 -, ligand with demonstrated efficacy in epilepsy, neuropathic pain, and anxiety disorders. PGB is highly efficacious as adjunctive therapy in patients with refractory partial seizures. Methods: Given its efficacy as adjunctive therapy, the potential for interaction of PGB with other antiepileptic drugs (AEDs) was assessed in patients with partial epilepsy in open-label, multiple-dose studies. Patients received PGB, 600 mg/day (200 mg q8h) for 7 days, in combination with their individualized maintenance monotherapy with valproate (VPA), phenytoin (PHT), lamotrigine (LTG), or carbamazepine (CBZ). Results: Trough steady-state concentrations of CBZ (and its epoxide metabolite), PHT, LTG, and VPA were unaffected by concomitant PGB administration. Likewise, PGB steady-state pharmacokinetic parameter values were similar among patients receiving CBZ, PHT, LTG, or VPA and, in general, were similar to those observed historically in healthy subjects receiving PGB alone. The PGB,AED combinations were generally well tolerated. PGB may be added to VPA, LTG, PHT, or CBZ therapy without concern for pharmacokinetic drug,drug interactions. [source] Clopidogrel: review of bioanalytical methods, pharmacokinetics/pharmacodynamics, and update on recent trends in drug,drug interaction studiesBIOMEDICAL CHROMATOGRAPHY, Issue 1 2009Ramesh Mullangi Abstract Clopidogrel, owing to its excellent inhibitory property of platelet aggregation, is used to reduce the cardiovascular risks in patients with multiple co-morbid conditions such as stroke, myocardial infarction and atherosclerosis. The current review focuses distinctly on three aspects: (a) an in-depth coverage on the bioanalytical methods for the quantification of clopidogrel and its inactive carboxylic acid metabolite as well as the active metabolite in pre-clinical and clinical samples; (b) an overview of the pharmacokinetic/pharmacodynamic aspects of clopidogrel; and (c) enumerating the key findings from drug,drug interaction studies of clopidogrel with various co-substrates such as lanzoprazole, fluvastatin, atorvastatin, pravastatin, digoxin, ketoconazole, donezepil and theophylline. Copyright © 2008 John Wiley & Sons, Ltd. [source] Development and validation of a high-sensitivity liquid chromatography/tandem mass spectrometry (LC/MS/MS) method with chemical derivatization for the determination of ethinyl estradiol in human plasma,BIOMEDICAL CHROMATOGRAPHY, Issue 7 2004Wilson Z. Shou Abstract An ultra-sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the analysis of oral contraceptive ethinyl estradiol (EE) was developed and validated over the curve range of 2.5,500 pg/mL using 1 mL of human plasma sample. Ethinyl estradiol and the internal standard, ethinyl estradiol tetra-deuterated (EE-d4), were extracted from the plasma matrix with methyl t -butyl ether, derivatized with dansyl chloride and then back-extracted into hexane. The hexane phase was evaporated to dryness, reconstituted and injected onto the LC/MS/MS system. The chromatographic separation was achieved on a Luna C18 column (50 × 2 mm, 5 µm) with an isocratic mobile phase of 20:80 (v/v) water:acetonitrile with 1% formic acid. The of,ine derivatization procedure introduced the easily ionizable tertiary amine function group to EE. This greatly improved analyte sensitivity in electrospray ionization and enabled us to achieve the desired lower limit of quantitation at 2.5 pg/mL. This high sensitivity method can be used for therapeutic drug monitoring or supporting bio-equivalence and drug,drug interaction studies in human subjects. Copyright © 2004 John Wiley & Sons, Ltd. [source] Everolimus drug interactions: application of a classification system for clinical decision makingBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 9 2006John M. Kovarik Abstract Introduction. More than half of all drugs used in medical practice are metabolized by cytochrome CYP3A. Coadministration of drugs that share this elimination pathway may lead to pharmacokinetic drug interactions. Efforts are underway by clinical, drug development and regulatory scientists to classify CYP3A-related drug interactions with the ultimate goal of improving guidance for clinical intervention. The CYP3A inhibitory classification system ranks inhibitors according to the fold-increase in area-under-the-curve (AUC) of a probe substrate as: strong (,5-fold), moderate (>2.0- to 4.9-fold), or weak (,2.0-fold). This classification system was applied to characterize everolimus as a CYP3A substrate. Methods. Five open-label crossover drug interaction studies were performed in 12,16 healthy subjects each. Subjects received a single 2 mg dose of everolimus alone and again during single- or multiple-dose treatment with the probe inhibitors ketoconazole, erythromycin, verapamil, cyclosporine and atorvastatin. Results. The fold-increase in everolimus AUC was: 15.0 with the strong inhibitor ketoconazole; 4.4, 3.5 and 2.7 with the moderate inhibitors erythromycin, verapamil and cyclosporine; and no change with the weak inhibitor atorvastatin. Subjects with low baseline AUCs when everolimus was given alone tended to have AUC increases of a higher magnitude (more potent interaction) in the presence of an inhibitor. Conclusions. Strong CYP3A inhibitors should be avoided when possible during everolimus treatment as compensatory everolimus dose reductions could be difficult to manage. Everolimus therapeutic drug monitoring should be used to guide individualized dose adjustments when moderate CYP3A inhibitors are added to or withdrawn from the regimen. Routine everolimus therapeutic drug monitoring should be sufficient to determine whether dose adjustments are needed when weak CYP3A inhibitors are coadministered. This rational and systematic approach to drug interactions on everolimus yielded clinically useful, structured guidelines for dose adjustment. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, in healthy subjectsBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 1 2010Hyunmi Kim WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Woohwangcheongsimwon suspension has traditionally been used for the treatment and prevention of stroke, hypertension, palpitations, convulsions and unconsciousness in various Asian countries. , Woohwangcheongsimwon suspensions showed an inhibitory effect on CYP2B6 activity in vitro. Two terpenoids, borneol and isoborneol, are major constituents of woohwangcheongsimwon suspension, and show a competitive inhibition of CYP2B6 with Ki values of 9.5 and 5.9 µm, respectively. , Bupropion undergoes metabolic transformation to the active metabolite, 4-hydroxybupropion, primarily via CYP2B6 both in vivo and in vitro. It is often used as a CYP2B6 substrate for clinical drug,drug interaction studies. , Drug interactions may occur between woohwangcheongsimwon suspension and bupropion. WHAT THIS STUDY ADDS , Co-administration with woohwangcheongsimwon suspension did not alter the pharmacokinetics of bupropion or its metabolite, 4-hydroxybupropion. , Dosage adjustment of bupropion is unnecessary in patients concomitantly administered the highest recommended daily dose of woohwangcheongsimwon suspension. AIMS To examine the effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, formed via CYP2B6 in vivo. METHODS A two-way crossover clinical trial with a 2 week washout period was conducted in 14 healthy volunteers. In phases I and II, subjects received 150 mg bupropion with or without woohwangcheongsimwon suspension four times (at ,0.17, 3.5, 23.5 and 47.5 h, with the time of bupropion administration taken as 0 h) in a randomized balanced crossover order. Bupropion and 4-hydroxybupropion plasma concentrations were measured for up to 72 h by LC-MS/MS. Urine was collected up to 24 h to calculate the renal clearance. In addition, the CYP2B6*6 genotype was also analyzed. RESULTS The geometric mean ratios and 90% confidence interval of bupropion with woohwangcheongsimwon suspension relative to bupropion alone were 0.976 (0.917, 1.04) for AUC(0,,) and 0.948 (0.830,1.08) for Cmax, respectively. The corresponding values for 4-hydroxybupropion were 0.856 (0.802, 0.912) and 0.845 (0.782, 0.914), respectively. The tmax values of bupropion and 4-hydroxybupropion were not significantly different between the two groups (P > 0.05). The pharmacokinetic parameters of bupropion and 4-hydroxybupropion were unaffected by woohwangcheongsimwon suspension. CONCLUSIONS These results indicate that woohwangcheongsimwon suspension has a negligible effect on the disposition of a single dose of bupropion in vivo. As a result, temporary co-administration with woohwangcheongsimwon suspension does not seem to require a dosage adjustment of bupropion. [source] | ||||||||||