scholarly journals Effects of a High-Fat Meal on the Relative Oral Bioavailability of Piperaquine

2005 ◽  
Vol 49 (6) ◽  
pp. 2407-2411 ◽  
Author(s):  
Ing-Kye Sim ◽  
Timothy M. E. Davis ◽  
Kenneth F. Ilett
Keyword(s):  
Oral Bioavailability ◽  
Geometric Mean ◽  
Pharmacokinetic Analysis ◽  
Lipid Solubility ◽  
Fasting State ◽  
High Fat ◽  
Time Curve ◽  
Hematological Indices ◽  
Concentration Time ◽  
Fat Meal

ABSTRACT Piperaquine (PQ) is an antimalarial drug whose high lipid solubility suggests that its absorption can be increased by a high-fat meal. We examined the pharmacokinetics of PQ phosphate (500 mg given orally) in the fasting state and after a high-fat meal in eight healthy Caucasian volunteers (randomized crossover). Plasma PQ concentration-time profiles were analyzed by using noncompartmental pharmacokinetic analysis. In the fed state, the geometric mean C max increased by 213%, from 21.0 to 65.8 μg/liter (P < 0.001). The time of C max was not significantly different between the fasting and fed states. The geometric mean area under the concentration-time curve from zero onward (AUC0-∞) increased by 98%, from 3,724 to 7,362 μg h/liter (P = 0.006). The oral bioavailability of PQ relative to the fasting state was 121% greater after the high-fat meal (95% confidence interval, 26 to 216% increase; P = 0.020). The side effects, postural blood pressure changes, electrocardiographic corrected QT interval, serum glucose, and other biochemical and hematological indices were similar in the fasting and fed states over 28 days of follow-up.

scholarly journals Pharmacokinetics of Ethambutol under Fasting Conditions, with Food, and with Antacids

1999 ◽  
Vol 43 (3) ◽  
pp. 568-572 ◽  
Author(s):  
Charles A. Peloquin ◽  
Amy E. Bulpitt ◽  
George S. Jaresko ◽  
Roger W. Jelliffe ◽  
James M. Childs ◽  
...  
Keyword(s):  
Maximum Concentration ◽  
Pharmacokinetic Model ◽  
Mass Spectrometry Data ◽  
Gas Chromatography Mass Spectrometry ◽  
High Fat ◽  
Time Curve ◽  
First Order ◽  
Concentration Time ◽  
Males And Females ◽  
Fat Meal

ABSTRACT Ethambutol (EMB) is the most frequent “fourth drug” used for the empiric treatment of Mycobacterium tuberculosis and a frequently used drug for infections caused by Mycobacterium avium complex. The pharmacokinetics of EMB in serum were studied with 14 healthy males and females in a randomized, four-period crossover study. Subjects ingested single doses of EMB of 25 mg/kg of body weight under fasting conditions twice, with a high-fat meal, and with aluminum-magnesium antacid. Serum was collected for 48 h and assayed by gas chromatography-mass spectrometry. Data were analyzed by noncompartmental methods and by a two-compartment pharmacokinetic model with zero-order absorption and first-order elimination. Both fasting conditions produced similar results: a mean (± standard deviation) EMB maximum concentration of drug in serum (C max) of 4.5 ± 1.0 μg/ml, time to maximum concentration of drug in serum (T max) of 2.5 ± 0.9 h, and area under the concentration-time curve from 0 h to infinity (AUC0–∞) of 28.9 ± 4.7 μg · h/ml. In the presence of antacids, subjects had a mean C maxof 3.3 ± 0.5 μg/ml, T max of 2.9 ± 1.2 h, and AUC0–∞ of 27.5 ± 5.9 μg · h/ml. In the presence of the Food and Drug Administration high-fat meal, subjects had a mean C max of 3.8 ± 0.8 μg/ml, T max of 3.2 ± 1.3 h, and AUC0–∞ of 29.6 ± 4.7 μg · h/ml. These reductions in C max, delays inT max, and modest reductions in AUC0–∞ can be avoided by giving EMB on an empty stomach whenever possible.

scholarly journals Pharmacokinetics and Absorption of Posaconazole Oral Suspension under Various Gastric Conditions in Healthy Volunteers

2008 ◽  
Vol 53 (3) ◽  
pp. 958-966 ◽  
Author(s):  
Gopal Krishna ◽  
Allen Moton ◽  
Lei Ma ◽  
Matthew M. Medlock ◽  
James McLeod
Keyword(s):  
Proton Pump ◽  
Gastric Motility ◽  
Nutritional Supplement ◽  
Gastric Ph ◽  
High Fat ◽  
Time Curve ◽  
Concentration Time ◽  
Dosing Frequency ◽  
Randomized Crossover Study ◽  
Fat Meal

ABSTRACT A four-part, randomized, crossover study with healthy subjects evaluated the effects of gastric pH, the dosing frequency and prandial state, food consumption timing, and gastric motility on the absorption of posaconazole. In part 1, a single dose (SD) of posaconazole (400 mg) was administered alone or with an acidic beverage or a proton pump inhibitor (PPI), or both. In part 2, posaconazole (400 mg twice daily and 200 mg four times daily) was administered for 7 days with and without a nutritional supplement (Boost). In part 3, an SD of posaconazole (400 mg) was administered while the subjects were fasting and before, during, and after a high-fat meal. In part 4, an SD of posaconazole (400 mg) and the nutritional supplement were administered alone, with metoclopramide, and with loperamide. Compared to the results obtained with posaconazole alone, administration with an acidic beverage increased the posaconazole maximum concentration in plasma (C max) and the area under the concentration-time curve (AUC) by 92% and 70%, respectively, whereas a higher gastric pH decreased the posaconazole C max and AUC by 46% and 32%, respectively. Compared to the results obtained with posaconazole alone, posaconazole at 400 mg or at 200 mg plus the nutritional supplement increased the posaconazole C max and AUC by 65% and 66%, respectively, and by up to 137% and 161%, respectively. Administration before a high-fat meal increased the C max and the AUC by 96% and 111%, respectively, while administration during and after the meal increased the C max and the AUC by up to 339% and 387%, respectively. Increased gastric motility decreased the C max and the AUC by 21% and 19%, respectively. Strategies to maximize posaconazole exposure in patients with absorption difficulties include administration with or after a high-fat meal, with any meal or nutritional supplement, with an acidic beverage, or in divided doses and the avoidance of proton pump inhibitors.

scholarly journals Effect of Steady-State Faldaprevir on the Pharmacokinetics of Steady-State Methadone and Buprenorphine-Naloxone in Subjects Receiving Stable Addiction Management Therapy

2014 ◽  
Vol 59 (1) ◽  
pp. 498-504 ◽  
Author(s):  
David Joseph ◽  
Michael J. Schobelock ◽  
Robert R. Riesenberg ◽  
Bradley D. Vince ◽  
Lynn R. Webster ◽  
...  
Keyword(s):  
Steady State ◽  
Maximum Dose ◽  
Geometric Mean ◽  
Pharmacokinetic Analysis ◽  
Pharmacokinetics And Pharmacodynamics ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
State Concentration ◽  
State Area

ABSTRACTThe effects of steady-state faldaprevir on the safety, pharmacokinetics, and pharmacodynamics of steady-state methadone and buprenorphine-naloxone were assessed in 34 healthy male and female subjects receiving stable addiction management therapy. Subjects continued receiving a stable oral dose of either methadone (up to a maximum dose of 180 mg per day) or buprenorphine-naloxone (up to a maximum dose of 24 mg-6 mg per day) and also received oral faldaprevir (240 mg) once daily (QD) for 8 days following a 480-mg loading dose. Serial blood samples were taken for pharmacokinetic analysis. The pharmacodynamics of the opioid maintenance regimens were evaluated by the objective and subjective opioid withdrawal scales. Coadministration of faldaprevir with methadone or buprenorphine-naloxone resulted in geometric mean ratios for the steady-state area under the concentration-time curve from 0 to 24 h (AUC0–24,ss), the steady-state maximum concentration of the drug in plasma (Cmax,ss), and the steady-state concentration of the drug in plasma at 24 h (C24,ss) of 0.92 to 1.18 for (R)-methadone, (S)-methadone, buprenorphine, norbuprenorphine, and naloxone, with 90% confidence intervals including, or very close to including, 1.00 (no effect), suggesting a limited overall effect of faldaprevir. Although individual data showed moderate variability in the exposures between subjects and treatments, there was no evidence of symptoms of opiate overdose or withdrawal either during the coadministration of faldaprevir with methadone or buprenorphine-naloxone or after faldaprevir dosing was stopped. Similar faldaprevir exposures were observed in the methadone- and buprenorphine-naloxone-treated subjects. In conclusion, faldaprevir at 240 mg QD can be coadministered with methadone or buprenorphine-naloxone without dose adjustment, although given the relatively narrow therapeutic windows of these agents, monitoring for opiate overdose and withdrawal may still be appropriate. (This study has been registered atClinicalTrials.govunder registration no. NCT01637922.)

scholarly journals Pharmacokinetic Interactions between the Hormonal Emergency Contraception, Levonorgestrel (Plan B), and Efavirenz

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Monica L. Carten ◽  
Jennifer J. Kiser ◽  
Awewura Kwara ◽  
Samantha Mawhinney ◽  
Susan Cu-Uvin
Keyword(s):  
Geometric Mean ◽  
Liver Function Tests ◽  
Open Label ◽  
Time Curve ◽  
Geometric Means ◽  
Concentration Time ◽  
Plan B ◽  
Effective Contraception ◽  
Grade 3 ◽  
Hiv Negative

Objectives. Compare the Plan B levonorgestrel (LNG) area under the concentration- time curve (AUC12) prior to and with efavirenz (EFV).Design. Prospective, open-label, single-arm, equivalence study.Methods. Healthy HIV-negative subjects underwent 12 hr intensive pharmacokinetic (PK) sampling following single dose LNG alone and after 14 days of EFV. Geometric means, Geometric Mean Ratios, and 90% confidence intervals (CI) are reported for PK Parameters.T-tests were utilized. Clinical parameters and liver function tests (LFTs) were assessed.Results. 24 women enrolled and 21 completed the study. With EFV, LNG AUC12was reduced 56% (95% CI: 49%, 62%) from 42.9 to 17.8 ng*hr/mL, and maximum concentration (Cmax⁡) was reduced 41% (95% CI: 33%, 50%) from 8.4 to 4.6 ng/mL. LNG was well tolerated with no grade 3 or 4 treatment-related toxicities.Conclusions. EFV significantly reduced LNG exposures. Higher LNG doses may be required with EFV. These results reinforce the importance of effective contraception in women taking EFV.

scholarly journals Pharmacokinetics of Lopinavir-Ritonavir with and without Nonnucleoside Reverse Transcriptase Inhibitors in Ugandan HIV-Infected Adults

2010 ◽  
Vol 54 (7) ◽  
pp. 2965-2973 ◽  
Author(s):  
C. Kityo ◽  
A. S. Walker ◽  
L. Dickinson ◽  
F. Lutwama ◽  
J. Kayiwa ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Geometric Mean ◽  
Oral Clearance ◽  
Reverse Transcriptase Inhibitors ◽  
Time Curve ◽  
Nonnucleoside Reverse Transcriptase Inhibitors ◽  
Concentration Time ◽  
Half Dose ◽  
Trial Participants ◽  
Dose Tablet

ABSTRACT We evaluated the pharmacokinetics of lopinavir-ritonavir with and without nonnucleoside reverse transcriptase inhibitors (NNRTIs) in Ugandan adults. The study design was a three-period crossover study (3 tablets [600 mg of lopinavir/150 mg of ritonavir {600/150 mg}], 4 capsules [533/133 mg], and 2 tablets [400/100 mg] twice a day [BD]; n = 40) of lopinavir-ritonavir with NNRTIs and a parallel one-period study (2 tablets BD; n = 20) without NNRTIs. Six-point pharmacokinetic sampling (0, 2, 4, 6, 8, and 12 h) was undertaken after observed intake with a standardized breakfast. Ugandan DART trial participants receiving efavirenz (n = 20), nevirapine (n = 18), and no NNRTI (n = 20) had median ages of 41, 35, and 37 years, respectively, and median weights of 60, 64, and 63 kg, respectively. For the no-NNRTI group, the geometric mean (percent coefficient of variation [%CV]) lopinavir area under the concentration-time curve from 0 to 12 h (AUC0-12) was 110.1 (34%) μg·h/liter. For efavirenz, the geometric mean lopinavir AUC0-12 (%CV) values were 91.8 μg·h/liter (58%), 65.7 μg·h/liter (39%), and 54.0 μg·h/liter (65%) with 3 tablets, 4 capsules, and 2 tablets BD, respectively, with corresponding (within-individual) geometric mean ratios (GMR) for 3 and 2 tablets versus 4 capsules of 1.40 (90% confidence interval [CI], 1.18 to 1.65; P = 0.002) and 0.82 (90% CI, 0.68 to 0.99; P = 0.09), respectively, and the apparent oral clearance (CL/F) values were reduced by 58% and 1%, respectively. For nevirapine, the geometric mean lopinavir AUC0-12 (%CV) values were 112.9 μg·h/liter (30%), 68.1 μg·h/liter (53%), and 61.5 μg·h/liter (52%), respectively, with corresponding GMR values of 1.66 (90% CI, 1.46 to 1.88; P < 0.001) and 0.90 (90% CI, 0.77 to 1.06; P = 0.27), respectively, and the CL/F was reduced by 57% and 7%, respectively. Higher values for the lopinavir concentration at 12 h (C 12) were observed with 3 tablets and efavirenz-nevirapine (P = 0.04 and P = 0.0005, respectively), and marginally lower C 12 values were observed with 2 tablets and efavirenz-nevirapine (P = 0.08 and P = 0.26, respectively). These data suggest that 2 tablets of lopinavir-ritonavir BD may be inadequate when dosed with NNRTIs in Ugandan adults, and the dosage should be increased by the addition of an additional adult tablet or a half-dose tablet (100/25 mg), where available.

scholarly journals Effects of food and sucralfate on a single oral dose of 500 milligrams of levofloxacin in healthy subjects.

1997 ◽  
Vol 41 (10) ◽  
pp. 2196-2200 ◽  
Author(s):  
L J Lee ◽  
B Hafkin ◽  
I D Lee ◽  
J Hoh ◽  
R Dix
Keyword(s):  
Oral Dose ◽  
Healthy Subjects ◽  
High Fat ◽  
Time Curve ◽  
Mean Values ◽  
Treatment Groups ◽  
The Mean ◽  
The Individual ◽  
Individual Profiles ◽  
Fat Meal

The effects of food and sucralfate on the pharmacokinetics of levofloxacin following the administration of a single 500-mg oral dose were investigated in a randomized, three-way crossover study with young healthy subjects (12 males and 12 females). Levofloxacin was administered under three conditions: fasting, fed (immediately after a standardized high-fat breakfast), and fasting with sucralfate given 2 h following the administration of levofloxacin. The concentrations of levofloxacin in plasma and urine were determined by high-pressure liquid chromatography. By noncompartmental methods, the maximum concentration of drug in serum (Cmax), the time to Cmax (Tmax), the area under the concentration-time curve (AUC), half-life (t1/2), clearance (CL/F), renal clearance (CLR), and cumulative amount of levofloxacin in urine (Ae) were estimated. The individual profiles of the drug concentration in plasma showed little difference among the three treatments. The only consistent effect of the coadministration of levofloxacin with a high-fat meal for most subjects was that levofloxacin absorption was delayed and Cmax was slightly reduced (Tmax, 1.0 and 2.0 h for fasting and fed conditions, respectively [P = 0.002]; Cmax, 5.9 +/- 1.3 and 5.1 +/- 0.9 microg/ml [90% confidence interval = 0.79 to 0.94] for fasting and fed conditions, respectively). Sucralfate, which was administered 2 h after the administration of levofloxacin, appeared to have no effect on levofloxacin's disposition compared with that under the fasting condition. Mean values of Cmax and AUC from time zero to infinity were 6.7 +/- 3.2 microg/ml and 47.9 +/- 8.4 microg x h/ml, respectively, following the administration of sucralfate compared to values of 5.9 +/- 1.3 microg/ml and 50.5 +/- 8.1 microg x h/ml, respectively, under fasting conditions. The mean t1/2, CL/F, CLR, and Ae values were similar among all three treatment groups. In conclusion, the absorption of levofloxacin was slightly delayed by food, although the overall bioavailability of levofloxacin following a high-fat meal was not altered. Finally, sucralfate did not alter the disposition of levofloxacin when sucralfate was given 2 h after the administration of the antibacterial agent, thus preventing a potential drug-drug interaction.

scholarly journals Open-Label Crossover Study of Primaquine and Dihydroartemisinin-Piperaquine Pharmacokinetics in Healthy Adult Thai Subjects

2014 ◽  
Vol 58 (12) ◽  
pp. 7340-7346 ◽  
Author(s):  
Borimas Hanboonkunupakarn ◽  
Elizabeth A. Ashley ◽  
Podjanee Jittamala ◽  
Joel Tarning ◽  
Sasithon Pukrittayakamee ◽  
...  
Keyword(s):  
Crossover Study ◽  
Hospital Admissions ◽  
Geometric Mean ◽  
Radical Cure ◽  
Open Label ◽  
Time Curve ◽  
Content Type ◽  
Concentration Time ◽  
Pharmacokinetic Assessment ◽  
Adult Volunteers

ABSTRACTDihydroartemisinin-piperaquine is an artemisinin-based combination treatment (ACT) recommended by the WHO for uncomplicatedPlasmodium falciparummalaria, and it is being used increasingly for resistant vivax malaria where combination with primaquine is required for radical cure. The WHO recently reinforced its recommendations to add a single dose of primaquine to ACTs to reduceP. falciparumtransmission in low-transmission settings. The pharmacokinetics of primaquine and dihydroartemisinin-piperaquine were evaluated in 16 healthy Thai adult volunteers in a randomized crossover study. Volunteers were randomized to two groups of three sequential hospital admissions to receive 30 mg (base) primaquine, 3 tablets of dihydroartemisinin-piperaquine (120/960 mg), and the drugs together at the same doses. Blood sampling was performed over 3 days following primaquine and 36 days following dihydroartemisinin-piperaquine dosing. Pharmacokinetic assessment was done with a noncompartmental approach. The drugs were well tolerated. There were no statistically significant differences in dihydroartemisinin and piperaquine pharmacokinetics with or without primaquine. Dihydroartemisinin-piperaquine coadministration significantly increased plasma primaquine levels; geometric mean ratios (90% confidence interval [CI]) of primaquine combined versus primaquine alone for maximum concentration (Cmax), area under the concentration-time curve from 0 h to the end of the study (AUC0–last), and area under the concentration-time curve from 0 h to infinity (AUC0–∞) were 148% (117 to 187%), 129% (103 to 163%), and 128% (102 to 161%), respectively. This interaction is similar to that described recently with chloroquine and may result in an enhanced radical curative effect. (This study has been registered at ClinicalTrials.gov under registration no. NCT01525511.)

scholarly journals Phase I Study Assessing the Pharmacokinetic Profile, Safety, and Tolerability of a Single Dose of Ceftazidime-Avibactam in Hospitalized Pediatric Patients

2016 ◽  
Vol 60 (10) ◽  
pp. 6252-6259 ◽  
Author(s):  
John S. Bradley ◽  
Jon Armstrong ◽  
Antonio Arrieta ◽  
Raafat Bishai ◽  
Shampa Das ◽  
...  
Keyword(s):  
Single Dose ◽  
Phase I ◽  
Pediatric Patients ◽  
Geometric Mean ◽  
Open Label ◽  
Serious Adverse Events ◽  
Time Curve ◽  
Age Cohorts ◽  
Concentration Time ◽  
Systemic Antibiotic Therapy

ABSTRACTThis study aimed to investigate the pharmacokinetics (PK), safety, and tolerability of a single dose of ceftazidime-avibactam in pediatric patients. A phase I, multicenter, open-label PK study was conducted in pediatric patients hospitalized with an infection and receiving systemic antibiotic therapy. Patients were enrolled into four age cohorts (cohort 1, ≥12 to <18 years; cohort 2, ≥6 to <12 years; cohort 3, ≥2 to <6 years; cohort 4, ≥3 months to <2 years). Patients received a single 2-h intravenous infusion of ceftazidime-avibactam (cohort 1, 2,000 to 500 mg; cohort 2, 2,000 to 500 mg [≥40 kg] or 50 to 12.5 mg/kg [<40 kg]; cohorts 3 and 4, 50 to 12.5 mg/kg). Blood samples were collected to describe individual PK characteristics for ceftazidime and avibactam. Population PK modeling was used to describe characteristics of ceftazidime and avibactam PK across all age groups. Safety and tolerability were assessed. Thirty-two patients received study drug. Mean plasma concentration-time curves, geometric mean maximum concentration (Cmax), and area under the concentration-time curve from time zero to infinity (AUC0–∞) were similar across all cohorts for both drugs. Six patients (18.8%) reported an adverse event, all mild or moderate in intensity. No deaths or serious adverse events occurred. The single-dose PK of ceftazidime and avibactam were comparable between each of the 4 age cohorts investigated and were broadly similar to those previously observed in adults. No new safety concerns were identified. (This study has been registered at ClinicalTrials.gov under registration no. NCT01893346.)

scholarly journals Novel Dosing Strategies Increase Exposures of the Potent Antituberculosis Drug Rifapentine but Are Poorly Tolerated in Healthy Volunteers

2015 ◽  
Vol 59 (6) ◽  
pp. 3399-3405 ◽  
Author(s):  
Kelly E. Dooley ◽  
Radojka M. Savic ◽  
Jeong-Gun Park ◽  
Yoninah Cramer ◽  
Richard Hafner ◽  
...  
Keyword(s):  
Healthy Adults ◽  
Tuberculosis Treatment ◽  
Phase Iii ◽  
Pharmacokinetic Analysis ◽  
Population Pharmacokinetic ◽  
Antituberculosis Drug ◽  
High Fat ◽  
Low Fat ◽  
Once Daily ◽  
Fat Meal

ABSTRACTRifapentine is a potent antituberculosis drug currently in phase III trials. Bioavailability decreases with increasing dose, yet high daily exposures are likely needed to improve efficacy and shorten the tuberculosis treatment duration. Further, the limits of tolerability are poorly defined. The phase I multicenter trial in healthy adults described here investigated two strategies to increase rifapentine exposures: dividing the dose or giving the drug with a high-fat meal. In arm 1, rifapentine was administered at 10 mg/kg of body weight twice daily and 20 mg/kg once daily, each for 14 days, separated by a 28-day washout; the dosing sequence was randomized. In arm 2, 15 mg/kg rifapentine once daily was given with a high-fat versus a low-fat breakfast. Sampling for pharmacokinetic analysis was performed on days 1 and 14. Population pharmacokinetic analyses were performed. This trial was stopped early for poor tolerability and because of safety concerns. Of 44 subjects, 20 discontinued prematurely; 11 of these discontinued for protocol-defined toxicity (a grade 3 or higher adverse event or grade 2 or higher rifamycin hypersensitivity). Taking rifapentine with a high-fat meal increased the median steady-state area under the concentration-time curve from time zero to 24 h (AUC0–24ss) by 31% (relative standard error, 6%) compared to that obtained when the drug was taken with a low-fat breakfast. Dividing the dose increased exposures substantially (e.g., 38% with 1,500 mg/day). AUC0–24sswas uniformly higher in our study than in recent tuberculosis treatment trials, in which toxicity was rare. In conclusion, two strategies to increase rifapentine exposures, dividing the dose or giving it with a high-fat breakfast, successfully increased exposures, but toxicity was common in healthy adults. The limits of tolerability in patients with tuberculosis remain to be defined. (AIDS Clinical Trials Group study A5311 has been registered at ClinicalTrials.gov under registration no. NCT01574638.)

scholarly journals Pharmacokinetics of Telbivudine in Healthy Subjects and Absence of Drug Interaction with Lamivudine or Adefovir Dipivoxil

2006 ◽  
Vol 50 (7) ◽  
pp. 2309-2315 ◽  
Author(s):  
Xiao-Jian Zhou ◽  
Barbara A. Fielman ◽  
Deborah M. Lloyd ◽  
George C. Chao ◽  
Nathaniel A. Brown
Keyword(s):  
Single Dose ◽  
Steady State ◽  
Plasma Concentration ◽  
Healthy Subjects ◽  
Adefovir Dipivoxil ◽  
Geometric Mean ◽  
Time Curve ◽  
Concentration Time ◽  
Plasma Pharmacokinetics ◽  
Plasma Concentration Time Curve

ABSTRACT Two phase I studies were conducted to assess the plasma pharmacokinetics of telbivudine and potential drug-drug interactions between telbivudine (200 or 600 mg/day) and lamivudine (100 mg/day) or adefovir dipivoxil (10 mg/day) in healthy subjects. Study drugs were administered orally. The pharmacokinetics of telbivudine were characterized by rapid absorption with biphasic disposition. The maximum concentrations in plasma (C max) were reached at median times ranging from 2.5 to 3.0 h after dosing. Mean single-dose C max and area under the plasma concentration-time curve from time zero to infinity (AUC0-∞) were 1.1 and 2.9 μg/ml and 7.4 and 21.8 μg · h/ml for the 200- and 600-mg telbivudine doses, respectively. Steady state was reached after daily dosing for 5 to 7 days. The mean steady-state C max and area under the plasma concentration-time curve over the dosing interval (AUCτ) were 1.2 and 3.4 μg/ml and 8.9 and 27.5 μg · h/ml for the 200- and 600-mg telbivudine repeat doses, respectively. The steady-state AUCτ of telbivudine was 23 to 57% higher than the single-dose values. Concomitant lamivudine or adefovir dipivoxil did not appear to significantly alter the steady-state plasma pharmacokinetics of telbivudine; the geometric mean ratios and associated 90% confidence interval (CI) for the AUCτ of telbivudine alone versus in combination were 106.3% (92.0 to 122.8%) and 98.6% (86.4 to 112.5%) when coadministered with lamivudine and adefovir dipivoxil, respectively. Similarly, the steady-state plasma pharmacokinetics of lamivudine or adefovir were not markedly affected by the coadministration of telbivudine; the geometric mean ratios and associated 90% CI, alone versus in combination with telbivudine, were 99.0% (87.1 to 112.4%) and 92.2% (84.0 to 101.1%), respectively, for the lamivudine and adefovir AUCτ values. Moreover, the combination regimens studied were well tolerated in all subjects. The results from these studies provide pharmacologic support for combination therapy or therapy switching involving telbivudine, lamivudine, and adefovir dipivoxil for the treatment of chronic hepatitis B virus infection.

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