Pharmacokinetics and safety of nelfinavir when used in combination with zidovudine and lamivudine in HIV-infected pregnant women: Pediatric AIDS Clinical Trials Group (PACTG) Protocol 353.

BACKGROUND: Combination antiretroviral regimens including nelfinavir (NFV) are commonly used in pregnancy. We studied the safety, antiviral effect, and pharmacokinetics of NFV and its M8 metabolite with two dosing regimens in combination with zidovudine (ZDV) and lamivudine (3TC) in HIV-infected pregnant women. METHOD: HIV-infected pregnant women between 14 and 34 weeks gestation received NFV (Cohort 1: 750 mg tid, n = 10; Cohort 2: 1250 mg bid, n = 23) with ZDV and 3TC. Serial blood sampling for NFV concentrations was performed antepartum (AP) and 6 weeks postpartum (PP). Maternal and cord blood samples were also obtained at delivery. NFV and M8 levels were determined by high-performance liquid chromatography. The pharmacokinetic (PK) target was an extrapolated NFV AUC0-24 > 30 mug . h/mL. Mothers were followed frequently for potential clinical and laboratory toxicity. RESULTS: Overall, NFV in combination with ZDV and 3TC was well tolerated. The PK target was met in 3/8 AP and 5/7 PP in Cohort 1 and 17/21 AP and 16/17 PP in Cohort 2. When Cohort 2 NFV PK parameters AP and PP were compared, median Cmax (3.90 microg/mL vs. 5.01 microg/mL, p < .05) and AUC0-24 (56.6 vs. 86.8 microg . h/mL, p < .05) were increased PP and oral clearance (Cl/F; 44.2 vs. 28.8 L/h, p < .05) was decreased PP. The average M8/NFV ratio was increased PP compared to AP (0.085 vs. 0.29, p < .001). Placental transfer of NFV was low with a median cord blood:maternal plasma ratio at delivery of 0.05. Maternal mean CD4+ T cell counts increased significantly and plasma HIV-1 RNA levels decreased from entry to delivery and 6 to 12 weeks postpartum. CONCLUSION: NFV used in combination with ZDV and 3TC was well tolerated in pregnant HIV-infected women and produced a significant improvement in HIV disease parameters. NFV drug exposure is inadequate in most pregnant women receiving 750 mg tid but is much improved with 1250 mg bid. NFV crosses the placenta poorly. The AP increase in NFV oral clearance and decrease in M8/NFV ratio suggest that CYP3A activity increases relative to CYP2C19 activity during pregnancy.

Single-dose pharmacokinetics and safety of the oral antiviral compound adefovir dipivoxil in children infected with human immunodeficiency virus type 1. The Pediatrics AIDS Clinical Trials Group.

The acyclic phosphonate analog adefovir is a potent inhibitor of retroviruses, including human immunodeficiency virus (HIV) type 1, and, unlike some antiviral nucleosides, does not require the initial phosphorylation step for its activity. Two oral dosages of the adefovir prodrug adefovir dipivoxil were evaluated in a phase I study with children with HIV infection. A total of 14 patients were stratified into age groups ranging from 6 months to 18 years of age. Eight patients received 1.5 mg of adefovir dipivoxil per kg of body weight, and six patients received 3.0 mg of adefovir dipivoxil per kg. Serum samples were obtained at intervals during the 8 h postdosing and were analyzed for adefovir concentrations. Patients were monitored for adverse effects. All samples collected resulted in quantifiable levels of adefovir (lower limit of quantitation, 25 ng/ml) from each patient. The areas under the concentration-versus-time curves (AUCs) were similar (P = 0.85) for the 1.5- and 3.0-mg/kg doses, while the apparent oral clearance (CL/F) was significantly higher (P = 0.05) for the 3-mg/kg dose. Pharmacokinetic parameters differed by patient age. In comparing those children older and younger than the median age of 5.1 years, AUC (P = 0.03), maximum concentration of drug in serum (P = 0.004), and the concentration at 8 h postdosing (P = 0.02) were significantly lower for the younger children. There were no significant differences for apparent volume of distribution and CL/F normalized to body surface area, but there was a suggestive difference in half-life (P = 0.07) among the subjects in the older and younger age groups. No significant adverse events were encountered. These data provide the basis for a multidose phase II study of adefovir dipivoxil in HIV-infected infants and children.

Use of human immunodeficiency virus (HIV) human hyperimmune immunoglobulin in HIV type 1-infected children (Pediatric AIDS clinical trials group protocol 273).

The clinical, immunologic, and virologic effects and the pharmacokinetics of human immunodeficiency virus (HIV) human hyperimmune immunoglobulin (HIVIG) were assessed in 30 HIV-infected children aged 2-11 years. All had moderately advanced disease with an immune complex-dissociated (ICD) p24 antigen >70 pg/mL and were on stable antiviral therapy. Three groups of 10 children received 6 monthly infusions of 200, 400, or 800 mg/kg of HIVIG, and serial immunologic and virologic assays were performed. HIVIG doses as high as 800 mg/kg were safe and well tolerated. The half-life of HIVIG, determined by serial p24 antibody titers, was 13-16 days, the volume of distribution was 102-113 mL/kg, and clearance was 5.6-6.0 mL/kg/day. Plasma ICD p24 decreased during the infusions, but CD4 cell levels, plasma RNA copy number, cellular virus, immunoglobulin levels, and neutralizing antibody titers were minimally affected by the infusions. Clinical status did not change during the 6-month infusion and 3-month follow-up periods.

Combination therapy with efavirenz, nelfinavir, and nucleoside reverse-transcriptase inhibitors in children infected with human immunodeficiency virus type 1. Pediatric AIDS Clinical Trials Group 382 Team.

BACKGROUND: Consistent long-term viral suppression has been difficult to achieve in children with human immunodeficiency virus type 1 (HIV-1) infection. We tested the safety and antiviral efficacy of a novel combination consisting of efavirenz, nelfinavir, and one or more nucleoside reverse-transcriptase inhibitors in 57 children previously treated with only nucleoside reverse-transcriptase inhibitors. METHODS: The children were monitored for 48 weeks after the initiation of therapy. We assessed plasma concentrations of efavirenz and nelfinavir, plasma HIV-1 RNA levels, and lymphocyte subpopulations. RESULTS: At base line, the 57 HIV-1-infected children (age range, 3.8 to 16.8 years) had a median of 699 CD4 cells per cubic millimeter and 10,000 copies of HIV-1 RNA per milliliter of plasma. The most common treatment-related effects of at least moderate severity were rash (in 30 percent of children), diarrhea (in 18 percent), neutropenia (in 12 percent), and biochemical abnormalities (in 12 percent). Serious side effects were uncommon. The mean values for the area under the curve for efavirenz and nelfinavir corresponded to expected values. In an intention-to-treat analysis, 76 percent of children had plasma HIV-1 RNA levels of less than 400 copies per milliliter after 48 weeks of therapy and 63 percent had levels of less than 50 copies per milliliter. A high plasma HIV-1 RNA level at base line significantly decreased the likelihood that plasma levels of HIV-1 RNA would become undetectable during treatment. CONCLUSIONS: In HIV-1-infected children who were previously treated with nucleoside reverse-transcriptase inhibitors, the combination of efavirenz, nelfinavir, and nucleoside reverse-transcriptase inhibitors was generally well tolerated and had a potent and sustained antiviral effect.

Phase I safety and pharmacokinetics study of micronized atovaquone in human immunodeficiency virus-infected infants and children. Pediatric AIDS Clinical Trials Group.

A phase I dose-escalating safety and pharmacokinetic study evaluated an oral suspension of micronized atovaquone (m-atovaquone) in infants and children stratified into age groups from 1 month to 12 years of age. Dosages of 10, 30, and 45 mg/kg of body weight/day were evaluated as single daily doses over a period of 12 days. Steady-state concentrations in plasma were determined on day 12, and single postdose concentrations were measured on days 1, 3, 5, 7, 9, 13, 15, 18, 21, and 24. Prior studies with adults suggest that the average plasma atovaquone concentration of 15 micrograms/ml is associated with therapeutic success in more than 95% of patients with Pneumocystis carinii pneumonitis. The results showed m-atovaquone to be safe and well tolerated. Dosages of 30 mg/kg/day were adequate to achieve an average steady-state concentration of greater than 15 micrograms/ml in children ages 1 to 3 months and 2 to 12 years, but a dosage of 45 mg/kg/day was needed to reach this concentration in infants 3 to 24 months of age. The oral suspension of atovaquone is safe and well tolerated in children. A single daily dose of 30 mg/kg provides bioavailability considered adequate for therapy of P. carinii pneumonia, but infants between 3 and 24 months of age may require a dosage of 45 mg/kg/day.