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Evaluation of Rapidly Disintegrating Vaginal Tablets of Tenofovir, Emtricitabine and Their Combination for HIV-1 Prevention.

ABSTRACT: Vaginal tablets are being developed as an alternative to gels as an inexpensive, discreet dosage form for the administration of microbicides. This work describes the pharmacokinetic (PK) evaluation of rapidly disintegrating vaginal tablets containing tenofovir (TFV, 10 mg), emtricitabine (FTC, 10 mg), and the combination of TFV and FTC (10 mg each) under in vitro and in vivo conditions, and in direct comparison to the clinical TFV 1% gel, a microbicide product in Phase III clinical testing. The PK of TFV and FTC from tablets were also evaluated in female rabbits following intravaginal administration. Direct comparison of a single dose of TFV tablets (intact or predissolved at 10 mg/mL) and TFV 1% gel showed no differences in the vaginal PK of TFV between groups; however systemic bioavailability of TFV was significantly higher from the gel. When rabbits were dosed either once or daily for seven days with intact tablets of TFV, FTC, or the combination of TFV/FTC, vaginal and systemic concentrations of TFV and FTC were unaffected by co-formulation. Moreover, plasma PK parameters were similar following a single dose or seven once-daily doses. Tissue concentrations of TFV and FTC in the cranial vagina 4 h after administration ranged between 104 and 105 ng/g. Concentrations of TFV-diphospate (TFV-DP, the active metabolite) were also high (over 103 ng/g or about 3000 to 6000 fmol/mg) in the cranial vagina 4 h after administration and similar to those measured following administration of TFV 1% gel. These data demonstrate that rapidly disintegrating vaginal tablets may be a suitable topical microbicide dosage form providing similar vaginal TFV PK to that of TFV 1% gel. The data also support co-administration of FTC with TFV in a single vaginal tablet to create a combination microbicide in a simple and inexpensive dosage form.

SUBMITTER: Clark MR

PROVIDER: S-EPMC4279136 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Evaluation of Rapidly Disintegrating Vaginal Tablets of Tenofovir, Emtricitabine and Their Combination for HIV-1 Prevention.

Clark Meredith R MR Peet M Melissa MM Davis Sarah S Doncel Gustavo F GF Friend David R DR

Pharmaceutics 20141208 4

Vaginal tablets are being developed as an alternative to gels as an inexpensive, discreet dosage form for the administration of microbicides. This work describes the pharmacokinetic (PK) evaluation of rapidly disintegrating vaginal tablets containing tenofovir (TFV, 10 mg), emtricitabine (FTC, 10 mg), and the combination of TFV and FTC (10 mg each) under in vitro and in vivo conditions, and in direct comparison to the clinical TFV 1% gel, a microbicide product in Phase III clinical testing. The ...[more]

PMID: 25494201

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Project description:BACKGROUND:Intravaginal rings (IVRs) can deliver antiretroviral (ARV) agents for HIV pre-exposure prophylaxis (PrEP), theoretically overcoming adherence concerns associated with frequent dosing. However, topical vaginal ARV drug delivery has not simultaneously led to sufficient rectal drug exposure to likely protect from HIV infection as a result of receptive anal intercourse (RAI). Unprotected RAI has a higher risk of infection per sex act and, for women, also can be associated with vaginal exposure during a single sexual encounter, especially in higher-risk subsets of women. The physiologically inflamed, activated, immune-cell dense colorectal mucosa is increasingly appreciated as the sexual compartment with highly significant risk; this risk is increased in the setting of co-infections. Ex vivo studies have shown that colorectal tissue and rectal fluid concentrations correlated with HIV protection. Given these important results, efforts to document colorectal compartment ARV drug concentration from pod-IVR delivery was assessed to determine if vaginal application could provide protective ARV levels in both compartments. METHODOLOGY/PRINCIPAL FINDINGS:A crossover clinical trial (N = 6) evaluated 7 d of continuous TDF pod-IVR use, a wash-out phase, followed by 7 d with a TDF-FTC pod-IVR. A subsequent clinical trial (N = 6) consisted of 7 d of continuous TDF-FTC-MVC pod-IVR use. Rectal fluids were collected on Day 7 at IVR removal in all three ARV-exposures (two Phase 1 trials) and drug concentrations quantified by LC-MS/MS. Median rectal fluid concentrations of TFV, the hydrolysis product of the prodrug TDF, were between 0.66 ng mg-1 (TDF pod-IVR group) and 1.11 ng mg-1 (TDF-FTC pod-IVR group), but below the analytical lower limit of quantitation in 5/6 samples in the TDF-FTC-MVC pod-IVR group. Unexpectedly, median FTC (TDF-FTC pod-IVR, 20.3 ng mg-1; TDF-FTC-MVC pod-IVR, 0.18 ng mg-1), and MVC rectal fluid concentrations (0.84 ng mg-1) were quantifiable and higher than their respective in vitro EC50 values in most samples. Due to participant burden in these exploratory trials, rectal fluid was used as a surrogate for rectal tissue, where drug concentrations are expected to be higher. CONCLUSIONS/SIGNIFICANCE:The concentrations of FTC and MVC in rectal fluids obtained in two exploratory clinical trials of IVRs delivering ARV combinations exceeded levels associated with in vitro efficacy in HIV inhibition. Unexpectedly, MVC appeared to depress the distribution of TFV and FTC into the rectal lumen. Here we show that vaginal delivery of ARV combinations may provide adherence and coitally independent dual-compartment protection from HIV infection during both vaginal and receptive anal intercourse.

Project description:BACKGROUND:In a previous trial of antiretroviral therapy (ART) involving pregnant women with human immunodeficiency virus (HIV) infection, those randomly assigned to receive tenofovir, emtricitabine, and ritonavir-boosted lopinavir (TDF-FTC-LPV/r) had infants at greater risk for very premature birth and death within 14 days after delivery than those assigned to receive zidovudine, lamivudine, and ritonavir-boosted lopinavir (ZDV-3TC-LPV/r). METHODS:Using data from two U.S.-based cohort studies, we compared the risk of adverse birth outcomes among infants with in utero exposure to ZDV-3TC-LPV/r, TDF-FTC-LPV/r, or TDF-FTC with ritonavir-boosted atazanavir (ATV/r). We evaluated the risk of preterm birth (<37 completed weeks of gestation), very preterm birth (<34 completed weeks), low birth weight (<2500 g), and very low birth weight (<1500 g). Risk ratios with 95% confidence intervals were estimated with the use of modified Poisson models to adjust for confounding. RESULTS:There were 4646 birth outcomes. Few infants or fetuses were exposed to TDF-FTC-LPV/r (128 [2.8%]) as the initial ART regimen during gestation, in contrast with TDF-FTC-ATV/r (539 [11.6%]) and ZDV-3TC-LPV/r (954 [20.5%]). As compared with women receiving ZDV-3TC-LPV/r, women receiving TDF-FTC-LPV/r had a similar risk of preterm birth (risk ratio, 0.90; 95% confidence interval [CI], 0.60 to 1.33) and low birth weight (risk ratio, 1.13; 95% CI, 0.78 to 1.64). As compared to women receiving TDF-FTC-ATV/r, women receiving TDF-FTC-LPV/r had a similar or slightly higher risk of preterm birth (risk ratio, 1.14; 95% CI, 0.75 to 1.72) and low birth weight (risk ratio, 1.45; 95% CI, 0.96 to 2.17). There were no significant differences between regimens in the risk of very preterm birth or very low birth weight. CONCLUSIONS:The risk of adverse birth outcomes was not higher with TDF-FTC-LPV/r than with ZDV-3TC-LPV/r or TDF-FTC-ATV/r among HIV-infected women and their infants in the United States, although power was limited for some comparisons. (Funded by the National Institutes of Health and others.).

Project description:BackgroundThe use of fixed-dose combination nucleoside reverse-transcriptase inhibitors (NRTIs) with a nonnucleoside reverse-transcriptase inhibitor or a ritonavir-boosted protease inhibitor is recommended as initial therapy in patients with human immunodeficiency virus type 1 (HIV-1) infection, but which NRTI combination has greater efficacy and safety is not known.MethodsIn a randomized, blinded equivalence study involving 1858 eligible patients, we compared four once-daily antiretroviral regimens as initial therapy for HIV-1 infection: abacavir-lamivudine or tenofovir disoproxil fumarate (DF)-emtricitabine plus efavirenz or ritonavir-boosted atazanavir. The primary efficacy end point was the time from randomization to virologic failure (defined as a confirmed HIV-1 RNA level > or = 1000 copies per milliliter at or after 16 weeks and before 24 weeks, or > or = 200 copies per milliliter at or after 24 weeks).ResultsA scheduled interim review by an independent data and safety monitoring board showed significant differences in virologic efficacy, according to the NRTI combination, among patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more. At a median follow-up of 60 weeks, among the 797 patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more, the time to virologic failure was significantly shorter in the abacavir-lamivudine group than in the tenofovir DF-emtricitabine group (hazard ratio, 2.33; 95% confidence interval, 1.46 to 3.72; P<0.001), with 57 virologic failures (14%) in the abacavir-lamivudine group versus 26 (7%) in the tenofovir DF-emtricitabine group. The time to the first adverse event was also shorter in the abacavir-lamivudine group (P<0.001). There was no significant difference between the study groups in the change from the baseline CD4 cell count at week 48.ConclusionsIn patients with screening HIV-1 RNA levels of 100,000 copies per milliliter or more, the times to virologic failure and the first adverse event were both significantly shorter in patients randomly assigned to abacavir-lamivudine than in those assigned to tenofovir DF-emtricitabine. (ClinicalTrials.gov number, NCT00118898.)

Project description:ObjectiveThis report presents tenofovir (TFV) alafenamide (TAF) and elvitegravir (EVG) fabricated into nanoparticles for subcutaneous delivery as prevention strategy.DesignProspective prevention study in humanized bone marrow-liver-thymus (hu-BLT) mice.MethodsUsing an oil-in-water emulsion solvent evaporation technique, TAF + EVG drugs were entrapped together into nanoparticles containing poly(lactic-co-glycolic acid). In-vitro prophylaxis studies (90% inhibition concentration) compared nanoparticles with drugs in solution. Hu-BLT (n = 5/group) mice were given 200 mg/kg subcutaneous, and vaginally challenged with HIV-1 [5 × 10 tissue culture infectious dose for 50% of cells cultures (TCID50)] 4 and 14 days post-nanoparticle administration (post-nanoparticle injection). Control mice (n = 5) were challenged at 4 days. Weekly plasma viral load was performed using RT-PCR. Hu-BLT mice were sacrificed and lymph nodes were harvested for HIV-1 viral RNA detection by in-situ hybridization. In parallel, CD34 humanized mice (3/time point) compared TFV and EVG drug levels in vaginal tissues from nanoparticles and solution. TFV and EVG were analyzed from tissue using liquid chromatograph-tandem mass spectrometry (LC-MS/MS).ResultsTAF + EVG nanoparticles were less than 200 nm in size. In-vitro prophylaxis indicates TAF + EVG nanoparticles 90% inhibition concentration was 0.002 μg/ml and TAF + EVG solution was 0.78 μg/ml. TAF + EVG nanoparticles demonstrated detectable drugs for 14 days and 72 h for solution, respectively. All hu-BLT control mice became infected within 14 days after HIV-1 challenge. In contrast, hu-BLT mice that received nanoparticles and challenged at 4 days post-nanoparticle injection, 100% were uninfected, and 60% challenged at 14 days post-nanoparticle injection were uninfected (P = 0.007; Mantel-Cox test). In-situ hybridization confirmed these results.ConclusionThis proof-of-concept study demonstrated sustained protection for TAF + EVG nanoparticles in a hu-BLT mouse model of HIV vaginal transmission.

Dataset Information

Evaluation of Rapidly Disintegrating Vaginal Tablets of Tenofovir, Emtricitabine and Their Combination for HIV-1 Prevention.

Publications

Evaluation of Rapidly Disintegrating Vaginal Tablets of Tenofovir, Emtricitabine and Their Combination for HIV-1 Prevention.

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