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TVF gel concentrations decrease significantly after sex
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The timing of tenofovir vaginal gel administration in relation to sexual intercourse affected the pharmacokinetics of the drug, with concentrations of tenofovir significantly decreasing after sex, according to recent findings.
“There is a significant reduction in tenofovir drug levels in cervicovaginal fluid and tissue when gel is applied prior to sex compared to no sex, suggesting that before and after sex dosing or sustained drug delivery may be optimal,” Betsy C. Herold, MD, of Albert Einstein College, and colleagues wrote in Clinical Infectious Diseases.
In the single-arm crossover study, the researchers evaluated 24 healthy couples in mutually monogamous relationships who were enrolled at the University of Pittsburgh and Case Western University between December 2012 and February 2014. The researchers collected cervicovaginal lavage (CVL) and tissue samples approximately 2 hours after sex, and they also collected samples at matched-timing, no-sex visits. Tenofovir vaginal gel 1% (TVF) was applied 1 or 24 hours before sex, or 1 hour before and 1 hour after sex. Herold and colleagues tested the CVL samples for drug concentration and anti-HIV activity, and analyzed the relationship between dose timing and drug concentration vs. drug concentration after no-sex visits.
The researchers found that the vaginal tissue concentrations of TVF decreased by a median of 75.1% (median IQR, 65.2%; P = .001) when gel was applied 1 hour before sex and by 71% (median IQR, 55.3%; P = .0003) when applied 24 hours before sex compared with matched no-sex visits. Cervical tissue concentrations decreased by a median of 74.5% (median IQR, 63.4%) when TVF was applied 1 hour before sex and 54.6% (median IQR, 55.2%; P = .0009) when gel was applied 24 hours before intercourse compared with dosing without sex.
An additional postcoital dose yielded a significant increase in vaginal and cervical TVF concentrations vs. the 1 hour before sex visit (P < .0001). The addition of dosing 1 hour before and 1 hour after sex led to TVF concentrations at least as high as those measured after the no-sex visits. HIV suppression as measured by post-sex CVL increased significantly from a median of 55.46% (median IQR, 53.92%) without TVF gel to 99.4% (median IQR, 7.16%) with dosing 1 hour before sex; 76.68% (median IQR, 56.69%) with dosing 24 hours before sex; and 99.81% (median IQR, 0.41%) with dosing at 1 hour before and 1 hour after sex.
“These data highlight the importance of conducting postcoital pharmacokinetic studies to inform the selection of drugs or drug combinations and to optimize dosing recommendations,” the researchers concluded. – by Jen Byrne
Disclosure: The researchers report no relevant financial disclosures.
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