scholarly journals Bayesian Parameter Estimates of Nelfinavir and Its Active Metabolite, Hydroxy-tert-Butylamide, in Infants Perinatally Infected with Human Immunodeficiency Virus Type 1

2005 ◽  
Vol 49 (2) ◽  
pp. 525-535 ◽  
Author(s):  
Salomé Payen ◽  
Albert Faye ◽  
Alexandra Compagnucci ◽  
Carlo Giaquinto ◽  
Diana Gibbs ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Body Weight ◽  
Human Immunodeficiency Virus Type ◽  
Active Metabolite ◽  
Population Pharmacokinetic Model ◽  
Pharmacokinetic Model ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Immunodeficiency Virus

ABSTRACT The objective of the present study was to develop a population pharmacokinetic model for nelfinavir mesylate (NFV) and nelfinavir hydroxy-tert-butylamide (M8), the most abundant metabolite of NFV, in infants vertically infected with human immunodeficiency virus type 1 and participating in the Paediatric European Network for Treatment of AIDS 7 study. Plasma NFV concentrations were determined during repeated NFV administrations (two to three times a day). Eighteen infants younger that age 2 years participated in this study. The doses administered ranged from 71 to 203 mg/kg of body weight/day. Pharmacokinetic parameter estimates were obtained by a compartmental approach by using a kinetic model to simultaneously fit NFV and M8 (active metabolite) concentrations. M8 was shown to be formation rate limited and was characterized by first-order rate constants of formation and elimination. Body weight was found to be a more appropriate predictor than age of the changes in (i) the rate of metabolism, (ii) the elimination rate constant of NFV, and (iii) NFV clearance. Population parameters were computed to account for the relationship between the rate of metabolism and body weight. The estimated NFV and M8 elimination half-lives were 4.3 and 2.04 h, respectively. The estimated NFV clearance was 2.13 liters/h/kg. The M8 concentration-to-NFV concentration ratio was 0.64 ± 0.44. In conclusion, the population pharmacokinetic model describing the dispositions of NFV and M8 should facilitate the design of future studies to elucidate the relative contributions of the parent compound and M8 to the pharmacological and toxic effects of NFV therapy.

scholarly journals Safety and Single-Dose Pharmacokinetics of Abacavir (1592U89) in Human Immunodeficiency Virus Type 1-Infected Children

1999 ◽  
Vol 43 (3) ◽  
pp. 609-615 ◽  
Author(s):  
Walter Hughes ◽  
James A. McDowell ◽  
Jerry Shenep ◽  
Patricia Flynn ◽  
Mark W. Kline ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Body Weight ◽  
High Performance ◽  
Age Groups ◽  
Area Under The Curve ◽  
Oral Solution ◽  
Parameter Estimates ◽  
Immunodeficiency Virus ◽  
The Mean

ABSTRACT Abacavir (formerly 1592U89) is a potent 2′-deoxyguanosine analog reverse transcriptase inhibitor that has been demonstrated to have a favorable safety profile in initial clinical trials with adults with human immunodeficiency virus (HIV) type 1 infection. A phase I study was conducted to evaluate the pharmacokinetics and safety of abacavir following the administration of two single oral doses (4 and 8 mg/kg of body weight) to 22 HIV-infected children ages 3 months to 13 years. Plasma was collected for analysis at predose and at 0.5, 1, 1.5, 2, 2.5, 3, 5, and 8 h after the administration of each dose. Plasma abacavir concentrations were determined by high-performance liquid chromatography, and data were analyzed by noncompartmental methods. Abacavir was well tolerated by all subjects. The single abacavir-related adverse event was rash, which occurred in 2 of 22 subjects. After administration of the oral solution, abacavir was rapidly absorbed, with the time to the peak concentration in plasma occurring within 1.5 h postdosing. Pharmacokinetic parameter estimates were comparable among the different age groups for each dose level. The mean maximum concentration in plasma (C max) and the mean area under the curve from time zero to infinity (AUC0–∞) increased by 16 and 45% more than predicted, respectively, as the abacavir dose was doubled from 4 to 8 mg/kg (C max increased from 1.69 to 3.94 μg/ml, and AUC0–∞ increased from 2.82 to 8.09 μg · h/ml). Abacavir was rapidly eliminated, with a mean elimination half-life of 0.98 to 1.13 h. The mean apparent clearance from plasma decreased from 27.35 to 18.88 ml/min/kg as the dose increased. Neither body surface area nor creatinine clearance were correlated with pharmacokinetic estimates at either dose. The extent of exposure to abacavir appears to be slightly lower in children than in adults, with the comparable unit doses being based on body weight. In conclusion, this study showed that abacavir is safe and well tolerated in children when it is administered as a single oral dose of 4 or 8 mg/kg.

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