Pharmacokinetics of the Protease Inhibitor Indinavir in Human Immunodeficiency Virus Type 1-Infected Children

ABSTRACT The objective of this study was to evaluate the pharmacokinetics of indinavir in human immunodeficiency virus-infected children as part of a prospective, open, uncontrolled, multicenter study in The Netherlands. Human immunodeficiency virus type 1-infected children were monitored over 6 months of treatment with zidovudine (120 mg/m2 every 8 h [q8h]), lamivudine (4 mg/kg of body weight q12h), and indinavir (33mg/kg of metabolic weight [MW] q8h). Four weeks after the start of treatment, the steady-state pharmacokinetics of indinavir were determined by high-pressure liquid chromatography. If patients had an indinavir area under the concentration-time curve (AUC) of below 10 or above 30 mg/liter · h, a dose increase or a dose reduction was made and pharmacokinetic measurements were repeated 4 weeks later. Nineteen patients started with the dose of 33 mg/kg of MW q8h. The median AUC (range) was 10.5 (2.8 to 51.0) mg/liter · h. The median AUC (range) in 17 children treated with 50 mg/kg of MW q8h was 20.6 (4.1 to 38.7) mg/liter · h. Finally, five patients had a dose increase to 67 mg/kg of MW q8h, resulting in a median AUC (range) of 36.6 (27.2 to 80.0) mg/liter · h. After 6 months of treatment, there were 11 children with an AUC of below 20 mg/liter · h, of whom 5 (45%) had a detectable viral load, while this was the case in none of the 11 children with an AUC of higher than 20 mg/liter · h. We conclude that the optimal dose of indinavir in children to obtain drug exposure similar to that observed in adult patients is 50 mg/kg of MW q8h, which approximates 600 mg/m2 q8h. It would even be better to adjust the indinavir dose based on an AUC of greater than 20 mg/liter · h.

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Steady-State Pharmacokinetics of Amprenavir Coadministered with Ritonavir in Human Immunodeficiency Virus Type 1-Infected Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.1.118-123.2003 ◽

2003 ◽

Vol 47 (1) ◽

pp. 118-123 ◽

Cited By ~ 26

Author(s):

Cecile Goujard ◽

Isabelle Vincent ◽

Jean-Luc Meynard ◽

Nathalie Choudet ◽

Diane Bollens ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Steady State ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Time Curve ◽

Concentration Time ◽

Immunodeficiency Virus ◽

The Mean ◽

Hiv 1

ABSTRACT The protease inhibitor (PI) ritonavir is used as a strong inhibitor of cytochrome P450 3A4, which boosts the activities of coadministered PIs, resulting in augmented plasma PI levels, simplification of the dosage regimen, and better efficacy against resistant viruses. The objectives of the present open-label, multiple-dose study were to determine the steady-state pharmacokinetics of amprenavir administered at 600 mg twice daily (BID) and ritonavir administered at 100 mg BID in human immunodeficiency virus type 1 (HIV-1)-infected adults treated with different antiretroviral combinations including or not including a nonnucleoside reverse transcriptase inhibitor (NNRTI). Nineteen patients completed the study. The steady-state mean minimum plasma amprenavir concentration (C min,ss) was 1.92 μg/ml for patients who received amprenavir and ritonavir without an NNRTI and 1.36 μg/ml for patients who received amprenavir and ritonavir plus efavirenz. For patients who received amprenavir-ritonavir without an NNRTI, the steady-state mean peak plasma amprenavir concentration (C max,ss) was 7.12 μg/ml, the area under the concentration-time curve from 0 to 10 h (AUC0-10) was 32.06 μg · h/ml, and the area under the concentration-time curve over a dosing interval (12 h) at steady-state (AUCss) was 35.74 μg · h/ml. Decreases in the mean values of C min,ss (29%), C max,ss (42%), AUC0-10 (42%), and AUCss (40%) for amprenavir occurred when efavirenz was coadministered with amprenavir-ritonavir. No unexpected side effects were observed. As expected, coadministration of amprenavir with ritonavir resulted in an amprenavir C min,ss markedly higher than those previously reported for the marketed dose of amprenavir. When amprenavir-ritonavir was coadministered with efavirenz, amprenavir-ritonavir maintained a mean amprenavir C min,ss above the mean 50% inhibitory concentration of amprenavir previously determined for both wild-type HIV-1 isolates and HIV-1 strains isolated from PI-experienced patients. These data support the use of low-dose ritonavir to enhance the level of exposure to amprenavir and increase the efficacy of amprenavir.

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Pharmacokinetics of Indinavir Combined with Low-Dose Ritonavir in Human Immunodeficiency Virus Type 1-Infected Children

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.5.1904-1907.2004 ◽

2004 ◽

Vol 48 (5) ◽

pp. 1904-1907 ◽

Cited By ~ 10

Author(s):

A. S. Bergshoeff ◽

P. L. A. Fraaij ◽

A. M. C. van Rossum ◽

G. Verweel ◽

L. H. Wynne ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Low Dose ◽

Geometric Mean ◽

Time Curve ◽

Minimum Concentration ◽

Concentration Time ◽

Immunodeficiency Virus

ABSTRACT So far, no pediatric doses for indinavir combined with ritonavir have been defined. This study evaluated the pharmacokinetics of 400 mg of indinavir/m2 combined with 125 mg of ritonavir/m2 every 12 h (q12h) in 14 human immunodeficiency virus type 1-infected children. The area under the concentration-time curve from 0 to 24 h and the minimum concentration of drug in serum for indinavir were similar to those for 800 mg of indinavir-100 mg of ritonavir q12h in adults, while the maximum concentration of drug in serum was slightly decreased, with geometric mean ratios (90% confidence intervals in parentheses) of 1.1 (0.87 to 1.3), 0.96 (0.60 to 1.5), and 0.80 (0.68 to 0.94), respectively.

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Didanosine reduces atevirdine absorption in subjects with human immunodeficiency virus infections.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.3.767 ◽

1996 ◽

Vol 40 (3) ◽

pp. 767-771 ◽

Cited By ~ 2

Author(s):

G D Morse ◽

M A Fischl ◽

M J Shelton ◽

M T Borin ◽

M R Driver ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Maximum Concentration ◽

Concurrent Administration ◽

Time Curve ◽

Concentration Time ◽

Immunodeficiency Virus ◽

Combination Regimens

Atevirdine is a nonnucleoside reverse transcriptase inhibitor with in vitro activity against human immunodeficiency virus type 1 and is currently in phase II clinical trials. Atevirdine is most soluble at a pH of < 2, and therefore, normal gastric acidity is most likely necessary for optimal bioavailability. Because of the rapid development of resistance in vitro, atevirdine is being evaluated in combination with didanosine and/or zidovudine in both two- and three-drug combination regimens. To examine the influence of concurrent didanosine (buffered tablet formulation) on the disposition of atevirdine, 12 human immunodeficiency virus type 1-infected subjects (mean CD4+ cell count, 199 cells per mm3; range, 13 to 447 cells/mm3) participated in a three-way, partially randomized, crossover, single-dose study to evaluate the pharmacokinetics of didanosine and atevirdine when each drug was given alone (treatments A and B, respectively) versus concurrently (treatment C). Concurrent administration of didanosine and atevirdine significantly reduced the maximum concentration of atevirdine in serum from 3.45 +/- 2.8 to 0.854 +/- 0.33 microM (P = 0.004). Likewise, the mean atevirdine area under the concentration-time curve from 0 to 24 h after administration of the combination was reduced to 6.47 +/- 2.2 microM.h (P = 0.004) relative to a value of 11.3 +/- 4.8 microM.h for atevirdine alone. Atevirdine had no statistically significant effect on the pharmacokinetic parameters of didanosine. Concurrent administration of single doses of atevirdine and didanosine resulted in a markedly lower maximum concentration of atevirdine in serum and area under the concentration-time curve, with a minimal effect on the disposition of didanosine. It is unknown whether an interaction of similar magnitude would occur under steady-state conditions; thus, combination regimens which include both atevirdine and didanosine should be designed so that their administration times are separated. Since the duration of the buffering effect of didanosine formulations is unknown, atevirdine should be given prior to didanosine.

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