Pharmacokinetics of antiretroviral drug varies with formulation in the target population of children with HIV-1.

The bioequivalence of formulations is usually evaluated in healthy adult volunteers. In our study in 19 HIV-1-infected Ugandan children (1.8-4 years of age, weight 12 to <15 kg) receiving zidovudine, lamivudine, and abacavir solutions twice a day for ≥24 weeks, the use of scored tablets allowed comparison of plasma pharmacokinetics of oral solutions vs. tablets. Samples were collected 0, 1, 2, 4, 6, 8, and 12 h after each child's last morning dose of oral solution before changing to scored tablets of Combivir (coformulated zidovudine + lamivudine) and abacavir; this was repeated 4 weeks later. Dose-normalized area under curve (AUC)(0-12) and peak concentration (C(max)) for the tablet formulation were bioequivalent with those of the oral solution with respect to zidovudine and abacavir (e.g., dose-normalized geometric mean ratio (dnGMR) (tablet:solution) for zidovudine and abacavir AUC(0-12) were 1.01 (90% confidence interval (CI) 0.87-1.18) and 0.96 (0.83-1.12), respectively). However, lamivudine exposure was ~55% higher with the tablet formulation (AUC(0-12) dnGMR = 1.58 (1.37-1.81), C(max) dnGMR = 1.55 (1.33-1.81)). Although the clinical relevance of this finding is unclear, it highlights the impact of the formulation and the importance of conducting bioequivalence studies in target pediatric populations.

Antiretroviral regimens in pregnancy and breast-feeding in Botswana.

BACKGROUND: The most effective highly active antiretroviral therapy (HAART) to prevent mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) in pregnancy and its efficacy during breast-feeding are unknown. METHODS: We randomly assigned 560 HIV-1-infected pregnant women (CD4+ count, > or = 200 cells per cubic millimeter) to receive coformulated abacavir, zidovudine, and lamivudine (the nucleoside reverse-transcriptase inhibitor [NRTI] group) or lopinavir-ritonavir plus zidovudine-lamivudine (the protease-inhibitor group) from 26 to 34 weeks' gestation through planned weaning by 6 months post partum. A total of 170 women with CD4+ counts of less than 200 cells per cubic millimeter received nevirapine plus zidovudine-lamivudine (the observational group). Infants received single-dose nevirapine and 4 weeks of zidovudine. RESULTS: The rate of virologic suppression to less than 400 copies per milliliter was high and did not differ significantly among the three groups at delivery (96% in the NRTI group, 93% in the protease-inhibitor group, and 94% in the observational group) or throughout the breast-feeding period (92% in the NRTI group, 93% in the protease-inhibitor group, and 95% in the observational group). By 6 months of age, 8 of 709 live-born infants (1.1%) were infected (95% confidence interval [CI], 0.5 to 2.2): 6 were infected in utero (4 in the NRTI group, 1 in the protease-inhibitor group, and 1 in the observational group), and 2 were infected during the breast-feeding period (in the NRTI group). Treatment-limiting adverse events occurred in 2% of women in the NRTI group, 2% of women in the protease-inhibitor group, and 11% of women in the observational group. CONCLUSIONS: All regimens of HAART from pregnancy through 6 months post partum resulted in high rates of virologic suppression, with an overall rate of mother-to-child transmission of 1.1%. (ClinicalTrials.gov number, NCT00270296.)

Comparison of gastrointestinal tolerability and patient preference for treatment with the 625 mg and 250 mg nelfinavir tablet formulations.

OBJECTIVES: To compare gastrointestinal (GI) tolerability and patient preference for the new 625 mg formulation of nelfinavir (NFV) and the marketed 250 mg tablets (Viracept) in HIV-1-infected patients. METHODS: Virologically controlled patients (n=126) treated with a nelfinavir (NFV) 250 mg-containing regimen for > or =8 weeks completed a stool diary for 14 days to assess baseline bowel function. After switching to the NFV 625 mg formulation [1250 mg twice a day (bid)] for 28 days, patients continued their stool diaries and at study completion answered a questionnaire regarding formulation preferences. RESULTS: The incidence and mean weekly duration of GI upset over a 2-week period were lower with NFV 625 mg than with NFV 250 mg (79.8% vs. 84.9% of patients and 2.1 vs. 3.0 days, respectively). Fewer patients experienced moderate or severe diarrhoea with NFV 625 mg (6.5% vs. 11.1%), and the incidence of investigator-assessed diarrhoea also decreased with NFV 625 mg. Importantly, there was a significant improvement overall in the incidence of diarrhoea (any grade) when patients switched to NFV 625 mg [38 of 124 (31%) improving, 69 of 124 (56%) stable and 17 of 124 (14%) worsening on NFV 625 mg; P<0.01]. At study completion, most patients expressed a preference to continue treatment with NFV 625 mg [112 of 122 (91.8%); P<0.0001], with only one patient (0.8%) preferring to resume treatment with NFV 250 mg. The new formulation was well tolerated with no new safety concerns. CONCLUSIONS: The new NFV 625 mg formulation is better tolerated and preferred by patients switching from NFV 250 mg tablets. By reducing the daily pill count and improving GI tolerability, the NFV 625 mg formulation may enhance patient adherence to NFV-containing antiretroviral regimens and thus potentially improve virological outcomes.

Synthesis of N-alkyl substituted indolocarbazoles as potent inhibitors of human cytomegalovirus replication.

The synthesis and antiviral evaluation of unsymmetrical indolocarbazole derivatives of Arcyriaflavin A, substituted with a range of alkyl groups at the indole nitrogen, is described. Structure-activity relationships in this series against human cytomegalovirus (HCMV) replication in cell culture are reported. Compound 4b was identified as potent inhibitor of HCMV (IC(50)=19 nM), which retained activity against a range of HCMV strains including ganciclovir resistant isolates.

A phase II trial of dual protease inhibitor therapy: amprenavir in combination with indinavir, nelfinavir, or saquinavir.

This study evaluated dual protease inhibitor (PI) regimens containing amprenavir (APV) in PI-naive, HIV-1-infected patients over 48 weeks. Patients were randomized to 800-mg APV combined with 800-mg indinavir (IDV), 750-mg nelfinavir (NFV), or 800-mg saquinavir-soft gel capsule (SGV-SGC), all three times daily without nucleoside reverse transcriptase inhibitors, or APV given alone for 3 weeks and then with 150-mg lamivudine (3TC) and 300-mg zidovudine (ZDV), twice daily. Dual PI therapy demonstrated substantial antiviral activity and was generally safe and well tolerated. Eight patients had virologic failure; 5 were receiving dual PI therapy and 3 were in the APV/3TC/ZDV arm. The protease I50V mutation characteristic of APV resistance was not observed, although other key PI mutations were selected in 4 patients failing therapy, 2 of whom had PI resistance at baseline.

Indolocarbazoles: potent, selective inhibitors of human cytomegalovirus replication.

In our search for new, safer anti-HCMV agents, we discovered that the natural product Arcyriaflavin A (la) was a potent inhibitor of HCMV replication in cell culture. A series of analogues (symmetrical indolocarbazoles) was synthesised to investigate structure activity relationships in this series against a range of herpes viruses (HCMV, VZV, HSV1, and 2). This identified a number of novel, selective and potent inhibitors of HCMV, 12,13-dihydro-2,10-difluoro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazol e-5,7-(6H)-dione (1d) being the best example (IC50=40 nM, therapeutic index > 1450). Compounds described in this series were generally poor inhibitors of protein kinase C betaII, and no correlation was found between the ability to inhibit HCMV and the enzyme PKC.

Synthesis and anti-herpes virus activity of 2'-deoxy-4'-thiopyrimidine nucleosides.

A series of 5-substituted 2'-deoxy-4'-thiopyrimidine nucleosides was synthesized and evaluated as potential antiviral agents. A number of analogues such as 2'-deoxy-5-propyl-4'-thiouridine (3ii), 2'-deoxy-5-isopropyl-4'-thiouridine (3iii), 5-cyclopropyl-2'-deoxy-4'-thiouridine (3iv), 2'-deoxy-4'-thio-5-vinyluridine (3viii), and 5-(2-chloroethyl)-2'-deoxy-4'-thiouridine (3xx) were found to be highly active against herpes simplex virus type-1 (HSV-1) and varicella zoster virus (VZV) in vitro with no significant cytotoxicity. The compound with the broadest spectrum of activity was 2'-deoxy-5-ethyl-4'-thiouridine (3i) which showed significant activity against HSV-1, HSV-2, and VZV.

Mode of action of (R)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine against herpesviruses.

The activity, metabolism, and mode of action of (R)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine (H2G) against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) and varicella-zoster virus (VZV) were studied. Compared to acyclovir (ACV), H2G has superior activity against VZV (50% inhibitory concentration of 2.3 microM) and Epstein-Barr virus (50% inhibitory concentration of 0.9 microM), comparable activity against HSV-1, and weaker activity against HSV-2. The antiviral effect on HSV-1 showed persistence after removal of compound. H2G was metabolized to its mono-, di- and triphosphate derivatives in virus-infected cells, with H2G-triphosphate being the predominant product. Only small amounts of H2G-triphosphate were detected in uninfected cells (1 to 10 pmol/10(6) cells), whereas the level in HSV-1-infected cells reached 1,900 pmol/10(6) cells. H2G was a substrate for all three viral thymidine kinases and could also be phosphorylated by mitochondrial deoxyguanosine kinase. The intracellular half-life of H2G-triphosphate varied in uninfected (2.5 h) and infected (HSV-1, 14 h; VZV, 3.7 h) cells but was always longer than the half-life of ACV-triphosphate (1 to 2 h). H2G-triphosphate inhibited HSV-1, HSV-2, and VZV DNA polymerases competitively with dGTP (Ki of 2.8, 2.2, and 0.3 microM, respectively) but could not replace dGTP as a substrate in a polymerase assay. H2G was not an obligate chain terminator but would only support limited DNA chain extension. Only very small amounts of radioactivity, which were too low to be identified by high-performance liquid chromatography analysis of the digested DNA, could be detected in purified DNA from uninfected cells incubated with [3H]H2G. Thus, H2G acts as an anti-herpesvirus agent, particularly potent against VZV, by formation of high concentrations of relatively stable H2G-triphosphate, which is a potent inhibitor of the viral DNA polymerases.

Isolation and characterization of monoclonal antibodies raised against the reverse transcriptase of human immunodeficiency virus type 2 and cross-reactivity with that of type 1.

Monoclonal antibodies to human immunodeficiency virus (HIV)-2 reverse transcriptase have been raised with the ultimate goal of generating Fab fragments for future co-crystallization studies. A number of mouse monoclonal antibodies to recombinant HIV-2 reverse transcriptase have been obtained and characterized in terms of the possible epitopes they recognise together with cross-reactivity with a related reverse transcriptase. The antibodies were shown to fall into three groups that recognize different regions of the reverse transcriptase enzyme. One antibody, which recognizes part of the RNase H domain, demonstrated cross-reactivity between the HIV-1 and HIV-2 reverse transcriptase.