A multi-compartment single and multiple dose pharmacokinetic comparison of rectally applied tenofovir 1% gel and oral tenofovir disoproxil fumarate

Abstract

This Phase 1, randomized, two-site (United States), double-blind, placebo-controlled study enrolled 18 sexually abstinent men and women. All received a single 300-mg dose of oral tenofovir disoproxil fumarate (TDF) and were then randomized 2:1 to receive single and then seven daily rectal exposures of vaginally-formulated tenofovir (TFV) 1% gel or a hydroxyethyl cellulose (HEC) placebo gel. Blood, colonic biopsies and rectal and vaginal mucosal fluids were collected after the single oral TDF, the single topical TFV gel dose, and after 7 days of topical TFV gel dosing for extracellular analysis of TFV and intracellular analysis of the active metabolite tenofovir diphosphate (TFVdp) in peripheral blood mononuclear cells (PBMCs) and isolated mucosal mononuclear cells (MMC), including CD4+ and CD4- cell subsets. With a single rectal dose, TFV plasma concentrations were 24–33 fold lower and half-life was 5 h shorter compared to a single oral dose (p = 0.02). TFVdp concentrations were also undetectable in PBMCs with rectal dosing. Rectal tissue exposure to both TFV and TFVdp was 2 to 4-log10 higher after a single rectal dose compared to a single oral dose, and after 7 daily doses, TFVdp accumulated 4.5 fold in tissue. TFVdp in rectal tissue homogenate was predictive (residual standard error, RSE = 0.47) of tissue MMC intracellular TFVdp concentration, with the CD4+ cells having a 2-fold higher TFVdp concentration than CD4- cells. TFV concentrations from rectal sponges was a modest surrogate indicator for both rectal tissue TFV and TFVdp (RSE = 0.67, 0.66, respectively) and plasma TFV (RSE = 0.38). TFV penetrates into the vaginal cavity after oral and rectal dosing, with rectal dosing leading to higher vaginal TFV concentrations (p<0.01). Trial registration: ClinicalTrials.gov NCT00984971.

Conflict of interest statement

Competing Interests: The study was funded by a U19 grant under the Integrated Preclinical-Clinical Program for HIV Topical Microbicides (IPCP-HTM), Division of AIDS, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH) (AI060614) and the NIAID's Microbicide Trials Network (5UM1AI068633). Additional support was provided by Gilead Sciences Inc.; the University of California, Los Angeles Center for AIDS Research (5P30 AI28697) Cores of Mucosal Immunology, Flow Cytometry and Biostatistics; the University of North Carolina-Chapel Hill Center for AIDS Research, Clinical Pharmacology/Analytical Chemistry Core (P30 AI50410); the Johns Hopkins Clinical Pharmacology Analytical Laboratory and CONRAD. The RMP-02/MTN-006 study was registered at www.ClinicalTrials.gov (NCT00984971) and the protocol can be found at http://www.mtnstopshiv.org. This analysis was supported by a contract with Advanced BioScience Laboratories, Inc., Rockville, MD, and its subcontractor, Alpha StatConsult LLC, through a NIH/NIAID/DAIDS contract: "Comprehensive Resources for HIV Microbicides and Biomedical Prevention" (#HHSN272201000001C). This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Figure 1. Study Design.

Figure 2. Sample Collection.

All 18 trial participants received a single oral dose of 300 mg TDF followed by intensive 24 h PK. After ∼2 week resting period, 12 subjects were randomized to receive a single rectal gel dose of 1% TFV gel with intensive 24 h PK followed, after ∼2 week resting period, by 6 sequential, daily, self-administered rectal 1% TFV gel doses with the 7th dose administered in-clinic with subsequent 24 h intensive PK.

Figure 3. TFV Plasma Half-life is shorter (p = 0.02) during rectal administration.

Plasma concentration-time profile is shown (median and interquartile range). Nominal time for single rectal dose was shifted right by 0.250 h and multiple rectal dose by 0.500 h for clarity. N = 18 for oral dose, 12 single rectal dose, 12 multiple rectal dose. (BLQ values are imputed as 0.01.)

Figure 4. Increasing TFV in Rectal Tissue Homogenate results in increased TFVdp.

There is a linear correlation between rectal tissue homogenate TFVdp and TFV (p = 0.04, robust RSE  = 0.37) with oral dosing only (solid line is mean prediction of TFVdp in rectal tissue from oral dosing). Shaded regions are the 10–90% confidence intervals of the mean predictions from robust linear regression model. There is no correlation during rectal dosing.

Figure 5. Rectal tissue exposure to TFV and TFVdp (median ± IQR) is higher during rectal dosing with multiple rectal dosing, resulting in accumulation of TFVdp.

Each set of figures documents the 30 min drug quantification in the left-side graph and the 24 hr in the right side graph in rectal tissue biopsy homogenate (5A, 5B) and isolated mucosal mononuclear immune cells (MMC) (5C). Comparisons performed with paired Wilcoxon signed-rank test; only a subset of patients gave both C30 min and C24 h samples. Figure S5A  =  TFVTissue; Figure S5B  =  TFVdpTissue; Figure S5C  =  TFVdpMMC. There is accumulation of TFV and TFVdp from multiple rectal dosing. Critical p for significance was 0.025 after Bonferroni correction.

Figure 6. TFVdp in rectal tissue homogenate is predictive of intracellular TFVdp concentration in isolated rectal mucosal mononuclear cells (MMCs), with higher levels of phosphorylation in the CD4+ T cells compared to CD4- T cells.

Intracellular TFVdp concentration in isolated rectal mucosal mononuclear cells increases linearly as TFVdp concentration in rectal tissue homogenate increases. (p

Figure 7. TFV quantification from rectal sponges is predictive of plasma TFV exposure during rectal dosing.

Plasma TFV exposure is correlated linearly with rectal sponge TFV exposure. (p

Figure 8. TFV (A) and TFVdp (B) concentrations in rectal tissue homogenate are predicted by Rectal Sponge TFV.

(pTFV  = 0.67, RSETFVdp  = 0.66) Shaded regions are the 10–90% confidence intervals of the mean predictions from robust linear regression model. The correlations are consistent regardless of administration route and number of doses.

Figure 9. There is vaginal penetration of TFV from both oral and topical rectal exposures.

(A) Vaginal fluid detection of both TFV and TFVdp concentration in vaginal fluid is higher following rectal dosing than following single oral dosing TFVdp. There is a linear correlation between vaginal fluid sponge TFV and plasma TFV concentrations (p10 higher with rectal administration than oral, seen with higher y-intercept. (p<0.001). (B) There is a linear correlation between vaginal fluid TFV and both rectal tissue TFV and TFVdp (p<0.01, robust RSETFV  = 0.47, RSETFVdp  = 0.13). Shaded regions are the 10–90% confidence intervals of the mean predictions from robust linear regression model. Solid line is mean vaginal fluid TFV concentration, dashed TFVdp.