Tenofovir and tenofovir disoproxil fumarate pharmacokinetics from intravaginal rings.
OBJECTIVE
To compare the distribution of tenofovir in sheep vaginal lumen, tissue, and plasma following topical delivery of the antiretroviral drug from intravaginal rings, either as tenofovir or the disoproxil fumarate prodrug.


METHODS
Comparative pharmacokinetic study in sheep.


METHODS
Intravaginal rings formulated to achieve equivalent release rates of tenofovir and its disoproxil fumarate prodrug were evaluated for 28 days in sheep, with four animals in each group. Drug concentrations were measured by high-performance liquid chromatography-mass spectrometry.


RESULTS
Tenofovir levels in cervicovaginal lavage were indistinguishable (P > 0.30) in both groups, but tissue levels in animals receiving the prodrug were 86-fold higher than those receiving tenofovir, and approximately 50 times higher than the level shown to be protective of HIV infection in the CAPRISA 004 trial.


CONCLUSIONS
This is the first study to compare the pharmacokinetics of tenofovir and its disoproxil fumarate prodrug administered topically to the vaginal tract. These in-vivo data show that the prodrug leads to significantly higher drug tissue levels than tenofovir, a finding that may have important implications for the development of preexposure prophylaxis strategies based on topical delivery of antivirals to the female genital tract.
Department of Chemistry, Oak Crest Institute of Science, Pasadena CA, USA.
John A
JA
Moss
Marc M
MM
Baum
Amanda M
AM
Malone
Sean
S
Kennedy
Etana
E
Kopin
Cali
C
Nguyen
Josh
J
Gilman
Irina
I
Butkyavichene
Robyn A
RA
Willis
Kathleen L
KL
Vincent
Massoud
M
Motamedi
Thomas J
TJ
Smith
D000225:Adenine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D000282:Administration, Intravaginal; D000818:Animals; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D063065:Organophosphonates / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011355:Prodrugs / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012756:Sheep; D000068698:Tenofovir; D044364:Vaginal Douching
D019380:Anti-HIV Agents; D063065:Organophosphonates; D011355:Prodrugs; D000068698:Tenofovir; D000225:Adenine