Search

Emtricitabine (FTC; Emtriva), a potent deoxycytidine nucleoside reverse transcriptase inhibitor, has recently been approved by the U.S. Food and Drug Administration for the treatment of human immunodeficiency virus (HIV) infection. In adults, FTC has demonstrated linear kinetics over a wide dose range, and FTC 200 mg once a day (QD) is the recommended therapeutic dose. A phase I open-label trial was conducted in children to identify an FTC dosing regimen that would provide comparable plasma exposure to that observed in adults at 200 mg QD. Two single oral doses of FTC (60 and 120 mg/m(2), up to a maximum of 200 mg, in solutions) were evaluated in HIV-infected children aged <18 years old. Children >/=6 years old also received a third dose of approximately 120 mg/m(2) in capsules. A total of 25 children (two <2 years old, eight 2 to 5 years old, eight 6 to 12 years old, and seven 13 to 17 years old) received at least two doses of FTC. Single escalating oral doses of FTC were well tolerated and produced dose-proportional plasma drug concentrations in children. The FTC pharmacokinetics was comparable between adults and children 22 months to 17 years of age. The capsule formulation provided approximately 20% higher plasma FTC exposure than the solution formulation. Using plasma area under the concentration-time curve (AUC) data at the 120-mg/m(2) dose, it is projected (based on dose proportionality) that a 6-mg/kg dose (up to a maximum of 200 mg) of FTC would produce plasma AUCs in children comparable to those in adults given a 200-mg dose (i.e., median of approximately 10 h. micro g/ml). This pediatric FTC dose is being evaluated in long-term phase II therapeutic trials in HIV-infected children.

Homozygosity for a 32-bp deletion in the CCR5 gene (CCR5delta32) has been shown to confer resistance to infection with the macrophage-tropic strain of human immunodeficiency virus (HIV) type 1. We examined the distribution of CCR5delta32 in 47 children (age range, 1.5 to 19 years), of whom 43 were infected with HIV, by the perinatal route (n = 41) or by the intravenous route (n = 2). The infected patients were classified as rapid progressors (RP) (n = 7) (CDC category C3 or death by 2 years of age), non-rapid progressors (NRP) (n = 17) (survival for > or =8 years after infection), or intermediate (n = 19). CCR5delta32 heterozygosity was found in two HIV-infected children, both NRP. None of the subjects were homozygous for CCR5delta32, and the remaining children had no evidence of CCR5delta32. The presence of CCR5delta32 heterozygosity in 4.8% of this, predominantly non-Caucasian population is consistent with the published distribution of the mutation. The finding that CCR5delta32 was present only in NRP and not in any RP is in agreement with previous reports suggesting that heterozygosity for CCR5delta32 may confer limited protection from disease progression.

A double-blind phase II trial compared zalcitabine (0.03 mg/kg/day) in combination with zidovudine (720 mg/m2/day) and zidovudine monotherapy in 250 clinically stable, previously zidovudine-treated, human immunodeficiency virus-infected children. The combination was well-tolerated except for an increased incidence of neutropenia (14%) compared with that in children receiving monotherapy (5%). No differences were noted for time to first AIDS-defining illness or death, neuropsychologic status, or weight Z scores. In patients in the combination arm, the CD4 cell count decline was slower (13% per year) than in patients receiving monotherapy (25% per year) (P = .03), and quantitative peripheral blood mononuclear cell virus load remained lower at all time points (P = .08). Deaths were fewer in patients receiving combination therapy (4) compared with those in patients receiving monotherapy (10) (P = .083). Thus, administration of zidovudine with zalcitabine to children with prior zidovudine treatment did not result in a significant increase in toxicity compared with that resulting from zidovudine monotherapy and demonstrated improvement in immunologic and virologic surrogate markers.