title: A Pilot Study Measuring the Distribution and Permeability of a Vaginal HIV Microbicide Gel Vehicle Using Magnetic Resonance Imaging, Single Photon Emission Computed Tomography/Computed Tomography, and a Radiolabeled Small Molecule.
abstract: Vaginal microbicide gels containing tenofovir have proven effective in HIV prevention, offering the advantage of reduced systemic toxicity. We studied the vaginal distribution and effect on mucosal permeability of a gel vehicle. Six premenopausal women were enrolled. In Phase 1, a spreading gel containing (99m)technetium-DTPA ((99m)Tc) radiolabel and gadolinium contrast for magnetic resonance imaging (MRI) was dosed intravaginally. MRI was obtained at 0.5, 4, and 24 h, and single photon emission computed tomography with conventional computed tomography (SPECT/CT) at 1.5, 5, and 25 h postdosing. Pads and tissues were measured for activity to determine gel loss. In Phase 2, nonoxynol-9 (N-9), containing (99m)Tc-DTPA, was dosed as a permeability control; permeability was measured in blood and urine for both phases. SPECT/CT showed the distribution of spreading gel throughout the vagina with the highest concentration of radiosignal in the fornices and ectocervix; signal intensity diminished over 25 h. MRI showed the greatest signal accumulation in the fornices, most notably 1-4 h postdosing. The median (interquartile range) isotope signal loss from the vagina through 6 h was 29.1% (15.8-39.9%). Mucosal permeability to (99m)Tc-DTPA following spreading gel was negligible, in contrast to N-9, with detectable radiosignal in plasma, peaking at 8 h (5-12). Following spreading gel dosing, 0.004% (0.001-2.04%) of the radiosignal accumulated in urine over 12 h compared to 8.31% (7.07-11.01%) with N-9, (p=0.043). Spreading gel distributed variably throughout the vagina, persisting for 24 h, with signal concentrating in the fornices and ectocervix. The spreading gel had no significant effect on vaginal mucosal permeability.
authors.affiliation: 1 The Division of Clinical Pharmacology, Department of Medicine, Johns Hopkins School of Medicine , Baltimore, Maryland.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Fuchs
authors.affiliation: 2 CONRAD, Eastern Virginia Medical School (EVMS) , Arlington, Virginia.
authors.forename: Jill L
authors.initials: JL
authors.lastname: Schwartz
authors.affiliation: 2 CONRAD, Eastern Virginia Medical School (EVMS) , Arlington, Virginia.
authors.forename: David R
authors.initials: DR
authors.lastname: Friend
authors.affiliation: 3 The Division of Gynecologic Specialties, Department of Gynecology and Obstetrics, Johns Hopkins School of Medicine , Baltimore, Maryland.
authors.forename: Jenell S
authors.initials: JS
authors.lastname: Coleman
authors.affiliation: 1 The Division of Clinical Pharmacology, Department of Medicine, Johns Hopkins School of Medicine , Baltimore, Maryland.
authors.forename: Craig W
authors.initials: CW
authors.lastname: Hendrix
mesh_terms: D000282:Administration, Intravaginal; D000328:Adult; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018592:Cross-Over Studies; D005260:Female; D015658:HIV Infections / Q000517:prevention & control*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010865:Pilot Projects; D011877:Radionuclide Imaging; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014621:Vagina / Q000737:chemistry*; D014622:Vaginal Creams, Foams, and Jellies / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D000890:Anti-Infective Agents; D014622:Vaginal Creams, Foams, and Jellies