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Dose-ranging pharmacokinetics, safety, and efficacy of a 90-day intravaginal ring delivering islatravir in pigtail macaques

A 3D-printed intravaginal ring delivering islatravir provides long-acting, user-controlled HIV protection, shown safe and fully effective against vaginal SHIV challenge in macaques over 90 days.

August 2026

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Intravaginal rings (IVRs) are attractive user-controlled delivery systems that can achieve sustained release of compounds for several weeks. We modeled in macaques a three-dimensional (3D)–printed IVR delivering the investigational nucleoside reverse transcriptase translocator inhibitor islatravir (ISL). Three IVRs with 15, 30, or 60 milligrams of ISL were used in 30-day pharmacokinetic and safety studies followed by 90-day studies to identify a dose that maintains the concentration of the active intracellular metabolite islatravir triphosphate (ISL-TP) above protective benchmarks. IVRs were safe and delivered ISL in a dose-dependent manner. In a challenge study involving 12 weekly low-dose vaginal exposures to SHIV162p3, six macaques treated with 60-milligram ISL IVRs for 90 days remained seronegative and SHIV RNA negative, while two untreated controls were infected. These data provide initial preclinical evidence that a 90-day extended-release ISL IVR is safe and offers complete protection in a stringent challenge model, warranting further clinical investigation.

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Resource Type:

Journal Article
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Citation:

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Authors: Srinivasan, P., King, J. L., Zhang, J., Young, I. C., Little, D., Cottrell, M. L., Sykes, C., Schauer, A. P., Mitchell, J., Kashuba, A. D. M., García-Lerma, J. G., Benhabbour, S. R., Smith, J. M.

Health Risks(s):

  • HIV
  • Unintended Pregnancy

Product type(s):

  • ARVs
  • HIVtreatment
  • Hormonal
  • IVR
  • MPTs

Topic(s):

  • Development
  • Trials

Working Group

  • Other

Additional Keywords:

intravaginal rings; mpts; clinical trials

URL of resource:

https://www.science.org/doi/10.1126/sciadv.aef3514

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