In a study appearing in JAMA, Anna Wald, M.D., M.P.H., of the University of Washington & Fred Hutchinson Cancer Research Center, Seattle, and colleagues compared the medications pritelivir and valacyclovir for reducing genital herpes simplex virus shedding and lesions in persons with recurrent genital herpes.
The treatment for genital herpes simplex virus (HSV) infections relies on the nucleoside analogues acyclovir, valacyclovir, or famciclovir administered either for each recurrence or daily to prevent recurrences. In addition, valacyclovir, when taken daily has been shown to reduce the risk of HSV-2 transmission to susceptible partners. However, the protection is only partial (approximately 50 percent), likely because these drugs neither completely inhibit genital viral shedding (when the virus is active and potentially transmissible to sexual partners). Alternative agents to treat HSV infections are needed.
For this crossover study, 91 participants (adults with 4 to 9 annual genital HSV-2 recurrences) were randomly assigned, 45 to receive pritelivir first, a different class of medication for genital herpes, and 46 to receive valacyclovir first. Participants took the first drug for 28 days followed by 28 days of washout before taking the second drug for 28 days. Throughout treatment, the participants collected genital swabs 4 times daily for HSV testing. The U.S. Food and Drug Administration placed the trial on clinical hold based on findings in a concurrent nonclinical toxicity study, and the sponsor terminated the study.
Treatment-emergent adverse events occurred in 62 percent of participants in the pritelivir group and 69 percent of participants in the valacyclovir group.
"Further research is needed to assess longer-term efficacy and safety," the authors write.