scholarly journals THE INFLUENCE OF PAROXETINE ON THE PHARMACOKINETICS OF ATOMOXETINE AND ITS MAIN METABOLITE

2015 ◽  
Vol 88 (4) ◽  
pp. 513-520 ◽  
Author(s):  
Ioana Todor ◽  
Adina Popa ◽  
Maria Neag ◽  
Dana Muntean ◽  
Corina Bocsan ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Active Metabolite ◽  
Multiple Dose ◽  
Plasma Concentrations ◽  
Pharmacokinetic Parameters ◽  
Extensive Metabolizers ◽  
Open Label ◽  
Main Metabolite ◽  
Daily Dose ◽  
Metabolite Pharmacokinetics

Background and aims. To evaluate the effects of paroxetine on the pharmacokinetics of atomoxetine and its main metabolite, 4-hydroxyatomoxetine-O-glucuronide, after coadministration of atomoxetine and paroxetine in healthy volunteers.Methods. 22 healthy volunteers, extensive metabolizers, took part in this open-label, non-randomized, clinical trial. The study consisted of two periods: Reference, when a single oral dose of 25 mg atomoxetine was administrated to each subject and Test, when 25 mg atomoxetine  and 20 mg paroxetine were coadministered. Between the two periods, the volunteers received an oral daily dose of 20-40 mg paroxetine, for 6 days. Atomoxetine and 4-hydroxyatomoxetine-O-glucuronide plasma concentrations were determined within the first 48 hours following drug administration. The pharmacokinetic parameters of both compounds were assessed using a non-compartmental method and the analysis of variance aimed at identifying any statistical significant differences between the pharmacokinetic parameters of atomoxetine and its main metabolite, corresponding to each study period.Results. Paroxetine modified the pharmacokinetic parameters of atomoxetine. Cmax increased from 221.26±94.93 to 372.53±128.28 ng/mL, while AUC0-t and AUC0-∞ also increased from 1151.19±686.52 to 6452.37±3388.76 ng*h/mL, and from 1229.15±751.04 to 7111.74±4195.17 ng*h/mL respectively. The main metabolite pharmacokinetics was also influenced by paroxetine intake, namely Cmax, AUC0-t and AUC0-∞ decreased from 688.76±270.27 to 131.01±100.43 ng*h/mL, and from 4810.93±845.06 to 2606.04±923.88 and from 4928.55±853.25 to 3029.82 ±941.84 respectively.Conclusions. Multiple-dose paroxetine intake significantly influenced atomoxetine and its active metabolite pharmacokinetics, causing a 5.8-fold increased exposure to atomoxetine and 1.6-fold reduced exposure to 4-hydroxyatomoxetine-O-glucuronide.

scholarly journals Evaluation of tramadol human pharmacokinetics and safety after co-administration of magnesium ions in randomized, single- and multiple-dose studies

2021 ◽  
Vol 73 (2) ◽  
pp. 604-614
Author(s):  
Piotr J. Rudzki ◽  
Katarzyna Jarus-Dziedzic ◽  
Monika Filist ◽  
Edyta Gilant ◽  
Katarzyna Buś-Kwaśnik ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Multiple Dose ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Pharmacokinetic Parameters ◽  
Human Pharmacokinetics ◽  
Magnesium Ions ◽  
Open Label ◽  
Multiple Dose Study ◽  
Dose Study

Abstract Background Magnesium ions (Mg2+) increase and prolong opioid analgesia in chronic and acute pain. The nature of this synergistic analgesic interaction has not yet been explained. Our aim was to investigate whether Mg2+ alter tramadol pharmacokinetics. Our secondary goal was to assess the safety of the combination. Methods Tramadol was administered to healthy Caucasian subjects with and without Mg2+ as (1) single 100-mg and (2) multiple 50-mg oral doses. Mg2+ was administered orally at doses of 150 mg and 75 mg per tramadol dosing in a single- and multiple-dose study, respectively. Both studies were randomized, open label, laboratory-blinded, two-period, two-treatment, crossover trials. The plasma concentrations of tramadol and its active metabolite, O-desmethyltramadol, were measured. Results A total of 25 and 26 subjects completed the single- and multiple-dose study, respectively. Both primary and secondary pharmacokinetic parameters were similar. The 90% confidence intervals for Cmax and AUC0-t geometric mean ratios for tramadol were 91.95–102.40% and 93.22–102.76%. The 90% confidence intervals for Cmax,ss and AUC0-τ geometric mean ratios for tramadol were 93.85–103.31% and 99.04–105.27%. The 90% confidence intervals for primary pharmacokinetic parameters were within the acceptance range. ANOVA did not show any statistically significant contribution of the formulation factor (p > 0.05) in either study. Adverse events and clinical safety were similar in the presence and absence of Mg2+. Conclusions The absence of Mg2+ interaction with tramadol pharmacokinetics and safety suggests that this combination may be used in the clinical practice for the pharmacotherapy of pain. Graphic abstract

Pharmacokinetic and Pharmacodynamic Interaction Between Allopurinol and Probenecid in Patients with Gout

2011 ◽  
Vol 38 (5) ◽  
pp. 904-910 ◽  
Author(s):  
SOPHIE L. STOCKER ◽  
GARRY G. GRAHAM ◽  
ANDREW J. McLACHLAN ◽  
KENNETH M. WILLIAMS ◽  
RICHARD O. DAY
Keyword(s):  
Clinical Trials ◽  
Active Metabolite ◽  
Plasma Concentrations ◽  
Open Label ◽  
Pharmacodynamic Interaction ◽  
Daily Dose ◽  
Renal Clearances ◽  
Blood And Urine Samples ◽  
Plasma Urate ◽  
Clinical Trials Registry

Objective.To investigate the pharmacokinetic and pharmacodynamic interaction between probenecid and oxypurinol (the active metabolite of allopurinol) in patients with gout.Methods.This was an open-label observational clinical study. Blood and urine samples were collected to measure oxypurinol and urate concentrations. We examined the effects of adding probenecid to allopurinol therapy upon plasma concentrations and renal clearances of urate and oxypurinol.Results.Twenty patients taking allopurinol 100–400 mg daily completed the study. Maximum coadministered doses of probenecid were 250 mg/day (n = 1), 500 mg/day (n = 19), 1000 mg/day (n = 7), 1500 mg/day (n = 3), and 2000 mg/day (n = 1). All doses except the 250 mg daily dose were divided and dosing was twice daily. Estimated creatinine clearances ranged from 28 to 113 ml/min. Addition of probenecid 500 mg/day to allopurinol therapy decreased plasma urate concentrations by 25%, from mean 0.37 mmol/l (95% CI 0.33–0.41) to mean 0.28 mmol/l (95% CI 0.24–0.32) (p < 0.001); and increased renal urate clearance by 62%, from mean 6.0 ml/min (95% CI 4.5–7.5) to mean 9.6 ml/min (95% CI 6.9–12.3) (p < 0.001). Average steady-state plasma oxypurinol concentrations decreased by 26%, from mean 11.1 mg/l (95% CI 5.0–17.3) to mean 8.2 mg/l (95% CI 4.0–12.4) (p < 0.001); and renal oxypurinol clearance increased by 24%, from mean 12.7 ml/min (95% CI 9.6–15.8) to mean 16.1 ml/min (95% CI 12.0–20.2) (p < 0.05). The additional hypouricemic effect of probenecid 500 mg/day appeared to be lower in patients with renal impairment.Conclusion.Coadministration of allopurinol with probenecid had a significantly greater hypouricemic effect than allopurinol alone despite an associated reduction of plasma oxypurinol concentrations. Australian Clinical Trials Registry ACTRN012606000276550.

Liquid Chromatography-Tandem Mass Spectrometry Method for Ticagrelor and its Active Metabolite Determination in Human Plasma: Application to a Pharmacokinetic Study

2020 ◽  
Vol 16 (5) ◽  
pp. 602-608
Author(s):  
Niloufar Marsousi ◽  
Serge Rudaz ◽  
Jules A. Desmeules ◽  
Youssef Daali
Keyword(s):  
Clinical Trial ◽  
Formic Acid ◽  
Human Plasma ◽  
Active Metabolite ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Studies ◽  
Healthy Male ◽  
Coronary Syndrome ◽  
Healthy Male Volunteers ◽  
Male Volunteers

Background: Ticagrelor is a highly recommended new antiplatelet agent for the treatment of patients with acute coronary syndrome at moderate or high ischemic risk. There is a real need for rapid and accurate analytical methods for ticagrelor determination in biological fluids for pharmacokinetic studies. In this study, a sensitive and specific LC-MS method was developed and validated for quantification of ticagrelor and its Active Metabolite (AM) in human plasma over expected clinical concentrations. Methods: Samples were handled by Liquid-Liquid Extraction (LLE). A linear gradient was applied with a mobile phase composed of formic acid 0.1% and acetonitrile with 0.1% of formic acid using a C18 reversed-phase column. MS spectra were obtained by electrospray ionization in negative mode and optimized at 521.4→360.9 m/z, 477.2→361.2 m/z and 528.1→367.9 m/z transitions for ticagrelor, AM and ticagrelor-d7, respectively. Results: This method allowed rapid elution, in less than 4 minutes, and quantification of concentrations as low as 2 ng/mL for ticagrelor and 1 ng/mL for AM using only 100 μL of human plasma. LLE using hexane/ethyl acetate (50/50) was an optimal compromise in terms of extraction recovery and endogenous compounds interference. Trueness values of 87.8% and 89.5% and precisions of 84.1% and 93.8% were obtained for ticagrelor and AM, respectively. Finally, the usefulness of the method was assessed in a clinical trial where a single 180 mg ticagrelor was orally administered to healthy male volunteers. Pharmacokinetic parameters of ticagrelor and its active metabolite were successfully determined. Conclusion: A sensitive and specific quantification LC-MS-MS method was developed and validated for ticagrelor and its active metabolite determination in human plasma. The method was successfully applied to a clinical trial where a single ticagrelor 180 mg dose was orally administered to healthy male volunteers. The described method allows quantification of concentrations as low as 2 ng/mL of ticagrelor and 1 ng/mL of the metabolite using only 100 μL of plasma.

scholarly journals Similar Results in Children with Asthma for Steady State Pharmacokinetic Parameters of Ciclesonide Inhaled with or without Spacer

2010 ◽  
Vol 4 ◽  
pp. CMPed.S4311 ◽  
Author(s):  
H. Boss ◽  
P. Minic ◽  
R. Nave
Keyword(s):  
Active Metabolite ◽  
Day Treatment ◽  
Systemic Exposure ◽  
Dose Inhaler ◽  
Pharmacokinetic Parameters ◽  
Metered Dose Inhaler ◽  
Inhaled Corticosteroid ◽  
Open Label ◽  
Metered Dose ◽  
Children With Asthma

Background Ciclesonide is an inhaled corticosteroid administered by a metered dose inhaler (MDI) to treat bronchial asthma. After inhalation, the inactive ciclesonide is converted by esterases in the airways to active metabolite desisobutyryl-ciclesonide (des-CIC). Aim To compare the pharmacokinetic (PK) parameters of des-CIC in children after administration of therapeutic dose of ciclesonide with and without spacer (AeroChamber Plus™). Methods Open-label, 3 period, cross over, repeated dose, PK study in 37 children with mild to moderate stable asthma (age: 6–11 y; body weight: 20–53 kg). During each 7-day treatment period, ciclesonide was inhaled once in the morning: A) 160 μg MDI with spacer, B) 80 μg MDI with spacer, and C) 160 μg MDI without spacer. Serum PK parameters of ciclesonide and des-CIC were determined on Day 7 of each period. The primary PK parameters were the AUCτ and Cmax for des-CIC. Results Inhaling ciclesonide with spacer led to a dose proportional systemic exposure (AUCτ) of des-CIC (0.316 μg*h/L for 80 μg and 0.663 μg*h/L for 160 μg). The dose-normalized systemic exposure for des-CIC (based on AUCτ) was 27% higher after inhalation of ciclesonide 80 μg or 160 μg with spacer than without spacer; the corresponding Cmax values for des-CIC were, respectively, 63% and 55% higher with spacer. No clinically relevant abnormalities or adverse drug reactions were observed. Conclusions Inhalation of therapeutic ciclesonide dose with spacer led to a slight increase in the systemic exposure of des-CIC, which does not warrant dose adjustment.

scholarly journals The Efficacy of Once-Daily Dose of Phenobarbital in Children with Generalized Tonic-Clonic Epilepsy

2018 ◽  
Vol 35 (7-8) ◽  
pp. 172-9
Author(s):  
Amril A. Burhany ◽  
Sofyan Ismael ◽  
Hardiono Pusponegoro
Keyword(s):  
Clinical Trial ◽  
Plasma Concentrations ◽  
Serum Levels ◽  
Control Group ◽  
Controlled Clinical Trial ◽  
Study Group ◽  
Once Daily ◽  
Daily Dose ◽  
Plasma Measurements ◽  
Better Than

In spite of its long half life, phenobarbital is still given twice-daily in the treatment of generalized tonic-clonic epilepsy. This study aims to determine if daily dose of phenobarbital given once differs to that given twice daily. Subjects of this unblinded controlled clinical trial were generalized tonic-clonic epilepsy patients ranging in age from 1-15 years. There were 40 study cases and 42 controls. We gave phenobarbital 4-6 mg/kg/day once-daily for study group and twice-daily dose for control group. History, physical and EEG examination and phenobarbital plasma measurements were obtained a t the beginning of the study and four weeks later. The ratio of the second to first phenobarbital plasma concentrations in the study group was 0.99 while in the control group it was 1.02. The proportion of seizure-free patients in the study group increased from 70% at the beginning to 85% at the end of study, and in the control group from 64.3% to 83.3%. Hyperactivity and irritability increased in both groups, and there were no significant differences in mean serum levels, seizures control, hyperactivity and irritability in both groups. Drowsiness was found in 50% of cases, but statistically significant decrease were found in study group. The compliance of the study group (92.5%) was significantly better than that of the control group (71.4%).

scholarly journals Lack of Effect of Efavirenz on the Pharmacokinetics of Tipranavir-Ritonavir in Healthy Volunteers

2009 ◽  
Vol 53 (11) ◽  
pp. 4840-4844 ◽  
Author(s):  
C. J. L. la Porte ◽  
J. P. Sabo ◽  
L. Béïque ◽  
D. W. Cameron
Keyword(s):  
Steady State ◽  
Multiple Dose ◽  
Healthy Adult ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Open Label ◽  
Multiple Dose Study ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Dose Study

ABSTRACT Previously it has been shown that tipranavir-ritonavir (TPV/r) does not affect efavirenz (EFV) plasma concentrations. This study investigates the effect of steady-state EFV on steady-state TPV/r pharmacokinetics. This was a single-center, open-label, multiple-dose study of healthy adult female and male volunteers. TPV/r 500/200 mg twice a day (BID) was given with food for 24 days. After dosing with TPV/r for 10 days, EFV 600 mg once a day was added to the regimen. Intensive pharmacokinetic (PK) sampling was done on days 10 and 24. Validated bioanalytical high-pressure liquid chromatography-tandem mass spectrometry methods were used to determine plasma tipranavir (TPV), ritonavir (RTV), and EFV concentrations. Thirty-four subjects were entered into the study, and 16 subjects completed it. The geometric mean ratios (90% confidence intervals) for TPV and RTV area under the curves, C maxs, and C mins comparing TPV/r alone and in combination with EFV were 0.97 (0.87 to 1.09), 0.92 (0.81 to 1.03), and 1.19 (0.93 to 1.54) for TPV and 1.03 (0.78 to 1.38), 0.92 (0.65 to 1.30), and 1.04 (0.72 to 1.48) for RTV. Frequently observed adverse events were diarrhea, headache, dizziness, abnormal dreams, and rash. EFV had no effect on the steady-state PK of TPV or RTV, with the exception of a 19% increase in the TPV C min, which is not clinically relevant. TPV/r can be safely coadministered with EFV and without the need for a dose adjustment.

scholarly journals Phenotypic differences in nebivolol metabolism and bioavailability in healthy volunteers

2015 ◽  
Vol 88 (2) ◽  
pp. 208-213 ◽  
Author(s):  
Corina Briciu ◽  
Maria Neag ◽  
Dana Muntean ◽  
Corina Bocsan ◽  
Anca Buzoianu ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Active Metabolite ◽  
Genetic Regulation ◽  
Standard Normal Distribution ◽  
Pharmacokinetic Analysis ◽  
Pharmacokinetic Parameters ◽  
Open Label ◽  
Phenotypic Differences ◽  
Standard Normal ◽  
Unique Distribution

Introduction: Nebivolol, a third-generation β-blocker, is subject to extensive first-pass metabolism and produces active β-blocking hydroxylated metabolites, like 4-OH-nebivolol. It is primarily a substrate of CYP2D6, a metabolic pathway that is under polymorphic genetic regulation. The objective of this study was to assess the metabolizer phenotype and to evaluate the interphenotype bioavailability and metabolism of nebivolol.Material and methods: Forty-three healthy volunteers were included in this open-label, non-randomized clinical trial and each volunteer received a single dose of 5 mg nebivolol. Non-compartmental pharmacokinetic analysis was performed to determine the pharmacokinetic parameters of nebivolol and its active metabolite. The phenotypic distribution was assessed based on the AUC (aria under the curve) metabolic ratio of nebivolol/4-OH-nebivolol and statistical analysis. An interphenotype comparison of nebivolol metabolism and bioavailability was performed based on the pharmacokinetic parameters of nebivolol and its active metabolite.Results: Nebivolol/4-OH-nebivolol AUC metabolic ratios were not characterized by a standard normal distribution. The unique distribution emphasized the existence of two groups and the 43 healthy volunteers were classified as follows: poor metabolizers (PMs)=3, extensive metabolizers (EMs)=40. The phenotype had a marked impact on nebivolol metabolism. The exposure to nebivolol was 15-fold greater for PMs in comparison to EMs.  Conclusion: 40 EMs and 3 PMs were differentiated by using the pharmacokinetic parameters of nebivolol and its active metabolite. The study highlighted the existence of interphenotype differences regarding nebivolol metabolism and bioavailability.

scholarly journals Pharmacokinetics of Liposomal Amphotericin B for Injection in Chinese Healthy Subjects Based on a Bioequivalence Study

2021 ◽  
Author(s):  
Xueyuan Zhang ◽  
Huanhuan Qi ◽  
Manman Wang ◽  
Yuhuan Ji ◽  
Chunlei Li ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Liposomal Amphotericin ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Bioequivalence Study ◽  
Liposomal Amphotericin B ◽  
Pharmacokinetic Parameters ◽  
Healthy Population ◽  
Open Label ◽  
Liposomal Form

Abstract Purpose: The aim of this study was to evaluate the pharmacokinetic characteristics and safety of Liposomal Amphotericin B for injection in healthy Chinese volunteers based on a pilot bioequivalence clinical trial between a generic formulation and Ambisome ® Methods: This randomized, two sequence, open label, single dose,two period crossover study was conducted in healthy volunteers at the dose of 2mg kg Blood samples were collected at pre defined time points up to 674 h after the start of the 2 h infusion. Plasma concentrations of total, unencapsulated and encapsulated amphotericin B were determined. Pharmacokinetic parameters were calculated using non compartmental model . The formulations were considered bioequivalent if the 90% confidence interval ls (CIs) of the geometric mean ratio of C max and AUC of both products for free and encapsulated amphotericin B were within80.00 1 25.00 for L n transformed data. Results and conclusion: All the 12subjects completed the two period study , no subjects withdrew the study. The plasma pharmacokinetic profile of liposomal amphotericin B based on free, encapsulated and total amphotericin B demonstrated the characteristics of a three compartment al model. The majority drug in the circulating system after IV infusion of liposomal amphotericin B is remained liposomal form . Pharmacokinetic behaviors in Chinese population w ere consistent with that in western healthy population based on total and unbound amphotericin B concentrations in plasma. The generic liposomal amphotericin B for injection is bioequivalent to Ambisome ® in terms of the Pharmacokinetic parameters for free, encapsulated and total amphotericin B. Trial registration number at National Medical Products Administration CTR20200885 . Date of registration: May 22 , 20 2 0.

scholarly journals Bioequivalence of levamlodipine besylate tablets in healthy Chinese subjects: A single-dose and two-period crossover randomized study

2020 ◽  
Author(s):  
Li Xin ◽  
Chenjing Wang ◽  
Ting Li ◽  
Yanping Liu ◽  
Shuqin Liu ◽  
...  
Keyword(s):  
Single Dose ◽  
Randomized Study ◽  
Plasma Concentrations ◽  
Bioequivalence Study ◽  
Pharmacokinetic Parameters ◽  
Open Label ◽  
Liquid Chromatography Tandem Mass ◽  
The Mean ◽  
Healthy Chinese ◽  
Chinese Subjects

Abstract Background: Levamlodipine, a calcium channel blocker, has been show act as a cardiovascular drug. To compare the pharmacokinetic parameters between levamlodipine (test formulation) at a single dose of 5 mg and amlodipine (reference formulation) at a single dose of 10 mg, the bioequivalence study was carried out.Methods: A single-dose randomized, open-label, two-period crossover study was designed in healthy Chinese subjects. 48 subjects were divided into fasted and fed groups equally. The subjects randomly received the test or reference formulations at the rate of 1:1. Following a 21-day washout period, the alternative formulations were received. The blood samples were collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 24, 36, 48, 72, 96, 120, 144, 168 hours later. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to determine the plasma concentrations of levamlodipine. Adverse events were recorded.Results: The 90% confidence intervals (CIs) of the ratio of geometric means (GMRs) of Cmax, AUC0-t, and AUC0-∞ under both fasted and fed conditions were within the prespecified bioequivalence limits between 80~125%. Under fasted conditions, 24 subjects were enrolled and completed the study. The mean Cmax was (2.70±0.49) ng/mL, AUC0-t was (141.32±36.24) ng×h/mL and AUC0-∞ was (157.14±45.65) ng×h/mL after a single dose of 5 mg levamlodipine. The mean Cmax was (2.83±0.52) ng/mL, AUC0-t was (153.62±33.96) ng×h/mL and AUC0-∞ was (173.05±41.78) ng×h/mL after a single dose of 10 mg amlodipine. Under fed conditions, 24 subjects were enrolled and completed the study. The mean Cmax was (2.73±0.55) ng/mL, AUC0-t was (166.93±49.96) ng×h/mL and AUC0-∞ was (190.99±70.89) ng×h/mL after a single dose of 5 mg levamlodipine. The mean Cmax was (2.87±0.81) ng/mL AUC0-t was (165.46±43.58) ng×h/mL and AUC0-∞ was (189.51±64.70) ng×h/mL after a single dose of 10 mg amlodipine. Serious adverse event was not observed.Conclusion: The trial confirmed that levamlodipine at a single dose of 5 mg and amlodipine at a single dose of 10 mg were bioequivalent under both fasted condition and fed condition.Trial registration: Cinicaltrials, NCT04411875. Registered 3 June 2020 - Retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0009W1Q&selectaction=Edit&uid=U00050YQ&ts=3&cx=-6iqkm8

scholarly journals Pharmacokinetic Study of Tenofovir Disoproxil Fumarate Combined with Rifampin in Healthy Volunteers

2005 ◽  
Vol 49 (2) ◽  
pp. 680-684 ◽  
Author(s):  
J. A. H. Droste ◽  
C. P. W. G. M. Verweij-van Wissen ◽  
B. P. Kearney ◽  
R. Buffels ◽  
P. J. vanHorssen ◽  
...  
Keyword(s):  
Tenofovir Disoproxil Fumarate ◽  
Multiple Dose ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Data ◽  
Open Label ◽  
Time Curve ◽  
Simultaneous Treatment ◽  
Minimum Concentration ◽  
Period 2 ◽  
Tenofovir Df

ABSTRACT Tenofovir disoproxil fumarate (tenofovir DF) was studied in combination with rifampin in 24 healthy subjects in a multiple-dose, open-label, single-group, two-period study. All subjects were given tenofovir DF at 300 mg once a day (QD) from days 1 to 10 (period 1). From days 11 to 20 the subjects received tenofovir DF at 300 mg combined with rifampin at 600 mg QD (period 2). The multiple-dose pharmacokinetics of tenofovir (day 10 and 20) and rifampin (day 20) were assessed. The drug-related adverse events (AEs) experienced during this study were mostly mild. Only one grade 3 AE possibly or probably related to the treatment (raised liver enzyme levels) occurred during period 2; the subject was withdrawn from the study. Pharmacokinetic data for 23 subjects were thus evaluable. Point estimates for the mean ratios of tenofovir with rifampin versus tenofovir alone for the area under the concentration-time curve from time zero to 24 h (AUC0-24), the maximum concentration of drug in plasma (C max), and the minimum concentration of drug in plasma (C min) were 0.88, 0.84, and 0.85, respectively. The 90% classical confidence intervals for AUC0-24, C max, and C min were 0.84 to 0.92, 0.78 to 0.90, and 0.80 to 0.91, respectively, thus suggesting pharmacokinetic equivalence. Similarly, coadministration of rifampin and tenofovir DF did not result in changes in the values of the tenofovir pharmacokinetic parameters. For rifampin, the values of the pharmacokinetic parameters found in this study were comparable to those found in the literature, indicating that tenofovir DF has no effect on the pharmacokinetics of rifampin. In conclusion, adaptation of either the rifampin or the tenofovir DF dose for the simultaneous treatment of tuberculosis and human immunodeficiency virus (HIV) infection in HIV-infected patients is probably not required.

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