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AE possibly or probably related to the treatment (raised liver enzyme levels) occurred during period 2; the subject was withdrawn from the study.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.

scholarly journals Effect of Telaprevir on the Pharmacokinetics of Buprenorphine in Volunteers on Stable Buprenorphine/Naloxone Maintenance Therapy

2012 ◽  
Vol 56 (7) ◽  
pp. 3641-3647 ◽  
Author(s):  
Xia Luo ◽  
Jose Trevejo ◽  
Rolf P. G. van Heeswijk ◽  
Frances Smith ◽  
Varun Garg
Keyword(s):  
Maintenance Therapy ◽  
Least Squares ◽  
Confidence Intervals ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Data ◽  
Open Label ◽  
Serious Adverse Events ◽  
Time Curve ◽  
Symptom Frequency ◽  
Single Sequence

ABSTRACTThis was an open-label, single-sequence trial in hepatitis C virus-negative volunteers on stable, individualized, buprenorphine maintenance therapy. Telaprevir at 750 mg every 8 h was coadministered with buprenorphine/naloxone (4:1 ratio as sublingual tablets) for 7 days with food. Pharmacokinetic profiles of buprenorphine, norbuprenorphine, and naloxone were measured over the 24-hour dosing interval on day −1 (buprenorphine/naloxone alone, reference) and day 7 of telaprevir coadministration (test). Geometric least-squares mean ratios and associated 90% confidence intervals of treatment ratios (test/reference) were calculated using log-transformed pharmacokinetic parameters. Opioid withdrawal symptoms were evaluated throughout the study (via questionnaires and pupillometry). Pharmacokinetic data were available for 14 and 13 volunteers on day −1 and day 7, respectively. The area under the concentration-time curve (AUC) for buprenorphine was unchanged and the maximum concentration of drug in serum (Cmax) for buprenorphine,Cmaxand AUC for norbuprenorphine, andCmaxnaxolone were modestly decreased during coadministration with telaprevir. Geometric least-squares mean ratios (90% confidence intervals) for buprenorphine were 0.80 (0.69, 0.93) for theCmaxand 0.96 (0.84, 1.10) for the AUC from 0 to 24 h (AUC0–24); for norbuprenorphine, values were 0.85 (0.66, 1.09) forCmaxand 0.91 (0.71, 1.16) for AUC0–24; for naloxone, theCmaxwas 0.84 (0.62, 1.13). Coadministration of telaprevir did not increase withdrawal symptom frequency, and there were no serious adverse events reported during or after completion of telaprevir coadministration. Results suggest dose adjustment may not be necessary when telaprevir and buprenorphine/naloxone are coadministered.

scholarly journals Determination of Appropriate Weight-Based Cutoffs for Empiric Cefazolin Dosing Using Data from a Phase 1 Pharmacokinetics and Safety Study of Cefazolin Administered for Surgical Prophylaxis in Pediatric Patients Aged 10 to 12 Years

2015 ◽  
Vol 59 (7) ◽  
pp. 4173-4180 ◽  
Author(s):  
Michael L. Schmitz ◽  
Jeffrey L. Blumer ◽  
Wes Cetnarowski ◽  
Christopher M. Rubino
Keyword(s):  
Pediatric Patients ◽  
Phase 1 ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Data ◽  
Time Data ◽  
Surgical Prophylaxis ◽  
Open Label ◽  
Time Curve ◽  
Concentration Time ◽  
Few Data

ABSTRACTDespite over 40 years of worldwide usage, relatively few data have been published on the pharmacokinetics of cefazolin in pediatric surgical patients. The primary objectives of this study were to examine the pharmacokinetics and safety of cefazolin in children 10 to 12 years of age (inclusive) receiving 1 or 2 g of cefazolin, based on body weight. This multiple-center, open-label study enrolled pediatric patients electively scheduled for surgical procedures who required cefazolin as part of their routine clinical management. Patients weighing ≥25 to <50 kg received a 1-g dose, and patients weighing ≥50 to ≤85 kg received a 2-g dose. Postdose pharmacokinetic and safety assessments were conducted following drug administration. Cefazolin concentration-time data were analyzed by using both noncompartmental and population pharmacokinetics methods. Monte Carlo simulations were performed to identify appropriate weight-based cutoffs for the dosing of children aged 10 to 17 years of age. Twelve patients were enrolled in this study and provided the requisite pharmacokinetic data. In general, cefazolin was well tolerated. The mean cefazolin terminal elimination half-life, clearance, and area under the concentration-time curve from time zero to infinity in this population were 1.95 h, 0.804 ml/min/kg, and 607 mg · h/liter, respectively. Patients weighing 50 to 60 kg exhibited elevated cefazolin exposures. Observed pharmacokinetic parameters and simulation results indicated that a weight-based cutoff of 60 kg is predicted to provide cefazolin exposure consistent with that observed in normal, healthy adults at recommended doses for surgical prophylaxis. (This study has been registered at ClinicalTrials.gov under registration no. NCT01904357.)

Effect of Terbinafine on Theophylline Pharmacokinetics in Healthy Volunteers

1998 ◽  
Vol 42 (3) ◽  
pp. 695-697 ◽  
Author(s):  
Eric F. Trépanier ◽  
Anne N. Nafziger ◽  
Guy W. Amsden
Keyword(s):  
Healthy Volunteers ◽  
Multiple Dose ◽  
Treatment Phase ◽  
Pharmacokinetic Parameters ◽  
Noncompartmental Analysis ◽  
Open Label ◽  
Time Curve ◽  
Blood Samples ◽  
Concentration Time ◽  
Randomized Crossover Study

ABSTRACT Twelve healthy volunteers were enrolled in an open-label, randomized, crossover study. Subjects received single doses of theophylline (5 mg/kg) with and without multiple-dose terbinafine, and 11 blood samples were collected over 24 h. The study phases were separated by a 4-week washout period. Theophylline serum data were modeled via noncompartmental analysis. When the control phase (i.e., no terbinafine) was compared to the treatment phase (terbinafine), theophylline exposure (the area under the serum concentration-time curve from time zero to infinity) increased by 16% (P= 0.03), oral clearance decreased by 14% (P = 0.04), and half-life increased by 24% (P = 0.002). No significant changes in other theophylline pharmacokinetic parameters were evident.

scholarly journals Herb-Drug Interaction betweenEchinacea purpureaand Darunavir-Ritonavir in HIV-Infected Patients

2010 ◽  
Vol 55 (1) ◽  
pp. 326-330 ◽  
Author(s):  
José Moltó ◽  
Marta Valle ◽  
Cristina Miranda ◽  
Samandhy Cedeño ◽  
Eugenia Negredo ◽  
...  
Keyword(s):  
High Performance ◽  
Geometric Mean ◽  
Echinacea Purpurea ◽  
The Body ◽  
Pharmacokinetic Parameters ◽  
Root Extract ◽  
Open Label ◽  
Fixed Sequence ◽  
Time Curve ◽  
Sequence Study

ABSTRACTThe aim of this open-label, fixed-sequence study was to investigate the potential ofEchinacea purpurea, a commonly used botanical supplement, to interact with the boosted protease inhibitor darunavir-ritonavir. Fifteen HIV-infected patients receiving antiretroviral therapy including darunavir-ritonavir (600/100 mg twice daily) for at least 4 weeks were included.E. purpurearoot extract capsules were added to the antiretroviral treatment (500 mg every 6 h) from days 1 to 14. Darunavir concentrations in plasma were determined by high-performance liquid chromatography immediately before and 1, 2, 4, 6, 8, 10, and 12 h after a morning dose of darunavir-ritonavir on days 0 (darunavir-ritonavir) and 14 (darunavir-ritonavir plus echinacea). Individual darunavir pharmacokinetic parameters were calculated by noncompartmental analysis and compared between days 0 and 14 with the geometric mean ratio (GMR) and its 90% confidence interval (CI). The median age was 49 (range, 43 to 67) years, and the body mass index was 24.2 (range, 18.7 to 27.5) kg/m2. Echinacea was well tolerated, and all participants completed the study. The GMR for darunavir coadministered with echinacea relative to that for darunavir alone was 0.84 (90% CI, 0.63-1.12) for the concentration at the end of the dosing interval, 0.90 (90% CI, 0.74-1.10) for the area under the concentration-time curve from 0 to 12 h, and 0.98 (90% CI, 0.82-1.16) for the maximum concentration. In summary, coadministration ofE. purpureawith darunavir-ritonavir was safe and well tolerated. Individual patients did show a decrease in darunavir concentrations, although this did not affect the overall darunavir or ritonavir pharmacokinetics. Although no dose adjustment is required, monitoring darunavir concentrations on an individual basis may give reassurance in this setting.

scholarly journals Lack of Effect of Zafirlukast on the Pharmacokinetics of Azithromycin, Clarithromycin, and 14-Hydroxyclarithromycin in Healthy Volunteers

1999 ◽  
Vol 43 (5) ◽  
pp. 1152-1155 ◽  
Author(s):  
Kevin W. Garey ◽  
Charles A. Peloquin ◽  
Paul G. Godo ◽  
Anne N. Nafziger ◽  
Guy W. Amsden
Keyword(s):  
Steady State ◽  
Healthy Subjects ◽  
High Performance ◽  
Pharmacokinetic Parameters ◽  
Steady State Concentration ◽  
Open Label ◽  
Time Curve ◽  
Data Analyses ◽  
Concentration Time ◽  
State Concentration

ABSTRACT This randomized, open-label, crossover study was conducted to investigate whether the coadministration of zafirlukast would affect the pharmacokinetics of azithromycin, clarithromycin, or 14-hydroxyclarithromycin (14-OHC). Twelve healthy subjects (six males and six females) received single 500-mg doses of azithromycin and clarithromycin with and without zafirlukast given to a steady-state concentration. Blood was collected prior to all macrolide doses and for 3 and 10 days after each clarithromycin and azithromycin dose, respectively. Serum was assayed for azithromycin, clarithromycin, and 14-OHC concentrations by validated high-performance liquid chromatography assay systems. Data analyses were done by noncompartmental and nonparametric methods. Analysis of the patients indicated that the addition of steady-state concentrations of zafirlukast did not significantly alter the pharmacokinetic parameters of or overall exposure (based on the area under the concentration-time curve) to azithromycin, clarithromycin, and 14-OHC. While zafirlukast is a known inhibitor of CYP3A4, it does not appear to exert a clinically or statistically significant pharmacokinetic effect on azithromycin, clarithromycin, or 14-OHC.

scholarly journals Pharmacokinetics and Safety of Famciclovir in Children with Herpes Simplex or Varicella-Zoster Virus Infection

2009 ◽  
Vol 53 (5) ◽  
pp. 1912-1920 ◽  
Author(s):  
X. Sáez-Llorens ◽  
R. Yogev ◽  
A. Arguedas ◽  
A. Rodriguez ◽  
M. G. Spigarelli ◽  
...  
Keyword(s):  
Herpes Simplex ◽  
Varicella Zoster Virus ◽  
Multiple Dose ◽  
Systemic Exposure ◽  
Varicella Zoster Virus Infection ◽  
Pharmacokinetic Data ◽  
Dosing Regimen ◽  
Open Label ◽  
Two Phase ◽  
Varicella Zoster

ABSTRACT Two multicenter, open-label, single-arm, two-phase studies evaluated single-dose pharmacokinetics and single- and multiple-dose safety of a pediatric oral famciclovir formulation (prodrug of penciclovir) in children aged 1 to 12 years with suspicion or evidence of herpes simplex virus (HSV) or varicella-zoster virus (VZV) infection. Pooled pharmacokinetic data were generated after single doses in 51 participants (∼12.5 mg/kg of body weight [BW] for children weighing <40 kg and 500 mg for children weighing ≥40 kg). The average systemic exposure to penciclovir was similar (6- to 12-year-olds) or slightly lower (1- to <6-year-olds) than that in adults receiving a 500-mg dose of famciclovir (historical data). The apparent clearance of penciclovir increased with BW in a nonlinear manner, proportional to BW0.696. An eight-step weight-based dosing regimen was developed to optimize exposure in smaller children and was used in the 7-day multiple-dose safety phases of both studies, which enrolled 100 patients with confirmed/suspected viral infections. Twenty-six of 47 (55.3%) HSV-infected patients who received famciclovir twice a day and 24 of 53 (45.3%) VZV-infected patients who received famciclovir three times a day experienced at least one adverse event. Most adverse events were gastrointestinal in nature. Exploratory analysis following 7-day famciclovir dosing regimen showed resolution of symptoms in most children with active HSV (19/21 [90.5%]) or VZV disease (49/53 [92.5%]). Famciclovir formulation (sprinkle capsules in OraSweet) was acceptable to participants/caregivers. In summary, we present a weight-adjusted dosing schedule for children that achieves systemic exposures similar to those for adults given the 500-mg dose.

scholarly journals Effect of Tipranavir-Ritonavir on Pharmacokinetics of Raltegravir

2009 ◽  
Vol 53 (7) ◽  
pp. 2752-2755 ◽  
Author(s):  
William D. Hanley ◽  
Larissa A. Wenning ◽  
Allison Moreau ◽  
James T. Kost ◽  
Eric Mangin ◽  
...  
Keyword(s):  
Geometric Mean ◽  
Study Drug ◽  
Integrase Inhibitor ◽  
Phase Iii ◽  
Open Label ◽  
Time Curve ◽  
Period 2 ◽  
Adverse Experiences ◽  
Immunodeficiency Virus

ABSTRACT Raltegravir (RAL) is a novel and potent human immunodeficiency virus type 1 integrase inhibitor that is predominantly metabolized via glucuronidation. The protease inhibitor combination tipranavir (TPV) at 500 mg and ritonavir (RTV) at 200 mg (TPV-RTV) has inhibitory and inductive effects on metabolic enzymes, which includes the potential to induce glucuronosyltransferase. Because RAL may be coadministered with TPV-RTV, there is the potential for the induction of RAL metabolism. Consequently, we assessed the effect of TPV-RTV on the pharmacokinetics of RAL and the safety and tolerability of this combination. Eighteen healthy adults were enrolled in this open-label study. The participants received RAL at 400 mg twice daily for 4 days (period 1) and TPV-RTV twice daily for 7 days (period 2), followed immediately by 400 mg RAL with TPV-RTV twice daily for 4 days (period 3). Under steady-state conditions, the RAL concentration at 12 h (C 12) was decreased when RAL was administered with TPV-RTV (geometric mean ratio [GMR], 0.45; 90% confidence interval [CI] 0.31, 0.66; P = 0.0021); however, the area under the concentration-time curve from time zero to 12 h (GMR, 0.76; 90% CI, 0.49, 1.19; P = 0.2997) and the maximum concentration in serum (GMR, 0.82; 90% CI, 0.46, 1.46; P = 0.5506) were not substantially affected. There were no serious adverse experiences or discontinuations due to study drug-related adverse experiences, and RAL coadministered with TPV-RTV was generally well tolerated. Although the RAL C 12 was decreased with TPV-RTV in this study, favorable efficacy data collected in phase III studies substantiate that TPV-RTV may be coadministered with RAL without dose adjustment.

scholarly journals Steady-State Pharmacokinetics of Abacavir in Plasma and Intracellular Carbovir Triphosphate following Administration of Abacavir at 600 Milligrams Once Daily and 300 Milligrams Twice Daily in Human Immunodeficiency Virus-Infected Subjects

2009 ◽  
Vol 53 (4) ◽  
pp. 1532-1538 ◽  
Author(s):  
Graeme Moyle ◽  
Marta Boffito ◽  
Carl Fletcher ◽  
Chris Higgs ◽  
Phillip E. Hay ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
High Performance ◽  
Pharmacokinetic Parameters ◽  
Virologic Suppression ◽  
Open Label ◽  
Time Curve ◽  
Mixed Effect ◽  
Once Daily ◽  
Immunodeficiency Virus ◽  
And Gender

ABSTRACT Abacavir (ABC) is administered either at 600 mg once daily (ABC 600 mg QD) or 300 mg twice daily (ABC 300 mg BID) in anti-human immunodeficiency virus (anti-HIV) combination therapy. Although ABC plasma pharmacokinetics following each regimen has been well defined, no study has directly compared the regimens with respect to pharmacokinetics of ABC's active intracellular anabolite, carbovir-triphosphate (CBV-TP). In an open-label, two-period, crossover study, 34 HIV-infected male and female subjects stabilized on antiretroviral regimens containing either ABC 600 mg QD or ABC 300 mg BID received their usual doses on days −1 and 1 and then switched regimens for days 2 to 11. Serial blood samples collected on days 1 and 11 were assayed for plasma ABC and intracellular CBV-TP concentrations using validated high-performance liquid chromatography-tandem mass spectrometry methods. Pharmacokinetic parameters were calculated using noncompartmental methods. Analysis of variance with a mixed-effect model was performed for treatment and gender comparisons. In 27 evaluable subjects, the regimens provided bioequivalent ABC daily areas under the concentration-time curve from 0 to 24 h (AUC0-24) and comparable CBV-TP concentrations at the end of the dosing interval (C τ). As expected, ABC QD resulted in 109% higher ABC maximum concentrations of drug in plasma (C max) than did ABC BID. ABC QD also resulted in 32% higher CBV-TP AUC0-24 and 99% higher CBV-TP C max than did ABC BID. Females had a 38% higher weight-adjusted ABC AUC0-24 and 81% higher weight-adjusted CBV-TP AUC0-24 than did males. Virologic suppression was maintained during regimen switch, and no tolerability differences between regimens were observed. In conclusion, this study showed that ABC 600 mg QD and ABC 300 mg BID regimens led to similar intracellular CBV-TP C τ values, thus providing pharmacokinetic support for the interchangeability of these two regimens. Women had higher intracellular CBV-TP exposure than did men.

scholarly journals Indinavir Pharmacokinetics and Parmacodynamics in Children with Human Immunodeficiency Virus Infection

2000 ◽  
Vol 44 (3) ◽  
pp. 752-755 ◽  
Author(s):  
Giorgio Gatti ◽  
Alessandra Vigano' ◽  
Natascia Sala ◽  
Stefano Vella ◽  
Matteo Bassetti ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Dosage Regimen ◽  
Renal Toxicity ◽  
Significant Negative Correlation ◽  
Pharmacokinetic Parameters ◽  
Pharmacokinetic Data ◽  
Time Curve ◽  
Number Of Patients ◽  
Immunodeficiency Virus ◽  
The Difference

ABSTRACT The indinavir dosage regimen currently used for human immunodeficiency virus (HIV)-infected children is not based on pharmacokinetic data obtained in the target patient population. The purpose of our study was to characterize indinavir pharmacokinetics and pharmacodynamics in HIV-infected children. Eleven children (age range, 9.0 to 13.6 years; weight range, 21.7 to 56.0 kg) receiving indinavir (500 mg/m2 every 8 h) in combination with lamivudine and stavudine were studied. The correlation of indinavir pharmacokinetic parameters and demographic parameters was evaluated. Also, the pharmacodynamic relationship between parameters of indinavir exposure and parameters of renal toxicity and immunologic recovery was studied. The area under the indinavir concentration-time curve (AUC) and patient body surface area (BSA) showed a significant negative correlation (r = 0.73; P = 0.012). Patients with smaller BSA had excessive indinavir AUC compared to adults. On the other hand, the median minimum drug concentration in plasma (C min) was lower than that reported for adults. The maximum indinavir concentration in serum was higher in patients with renal toxicity (5 out of 11 children), but the difference was not statistically significant (15.3 ± 8.2 versus 9.8 ± 4.4 mg/liter; P = 0.19). There was a trend toward higher immunologic efficacy in patients with greater indinavir exposure: the time-averaged AUC of the percentage of CD4+ lymphocytes over the baseline value for patients with indinavir C min > 95% inhibitory concentration (IC95) was higher than in patients withC min < IC95(P = 0.068). Our study suggests that a dose reduction may be appropriate for children with small BSA and that a 6-h dosage regimen may be indicated for a substantial percentage of patients. Due to the low number of patients enrolled in this study, our results should be confirmed by a larger study.

scholarly journals Pharmacokinetics of Ritonavir and Delavirdine in Human Immunodeficiency Virus-Infected Patients

2003 ◽  
Vol 47 (5) ◽  
pp. 1694-1699 ◽  
Author(s):  
Mark J. Shelton ◽  
Ross G. Hewitt ◽  
John Adams ◽  
Andrew Della-Coletta ◽  
Steven Cox ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Systemic Exposure ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Minimum Concentration ◽  
Mean Values ◽  
Immunodeficiency Virus ◽  
The Mean ◽  
Full Dosage ◽  
Delavirdine Mesylate

ABSTRACT To evaluate the pharmacokinetic effect of adding delavirdine mesylate to the antiretroviral regimens of human immunodeficiency virus (HIV)-infected patients stabilized on a full dosage of ritonavir (600 mg every 12 h), 12 HIV-1-infected subjects had delavirdine mesylate (400 mg every 8 h) added to their current antiretroviral regimens for 21 days. Ritonavir pharmacokinetics were evaluated before (day 7) and after (day 28) the addition of delavirdine, and delavirdine pharmacokinetics were evaluated on day 28. The mean values (± standard deviations) for the maximum concentration in serum (C max) of ritonavir, the area under the concentration-time curve from 0 to 12 h (AUC0-12), and the minimum concentration in serum (C min) of ritonavir before the addition of delavirdine were 14.8 ± 6.7 μM, 94 ± 36 μM · h, and 3.6 ± 2.1 μM, respectively. These same parameters were increased to 24.6 ± 13.9 μM, 154 ± 83 μM · h, and 6.52 ± 4.85 μM, respectively, after the addition of delavirdine (P is <0.05 for all comparisons). Delavirdine pharmacokinetic parameters in the presence of ritonavir included a C max of 23 ± 16 μM, an AUC0-8 of 114 ± 75 μM · h, and a C min of 9.1 ± 7.5 μM. Therefore, delavirdine increases systemic exposure to ritonavir by 50 to 80% when the drugs are coadministered.

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