In vitro release testing methods for drug-releasing vaginal rings

Peter Boyd, Bruce Variano, Patrick Spence, Clare F. McCoy, Diarmaid Murphy, Yahya Dallal Bashi, R. Karl Malcolm

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)
747 Downloads (Pure)


Drug-releasing vaginal rings are torus-shaped devices, generally fabricated from thermoplastics or silicone elastomers, used to administer pharmaceutical drugs to the human vagina for periods typically ranging from three weeks to twelve months. One of the most important product performance tests for vaginal rings is the in vitro release test. Although it has been fifty years since the a vaginal ring device was first described in the scientific literature, and despite seven drug-releasing vaginal rings having been approved for market, there is no universally accepted method for testing in vitro drug release, and only one non-compendial shaking incubator method (for the estradiol-releasing ring Estring®) is described in the US Food and Drug Administration's Dissolution Methods Database. Here, for the first time, we critically review the diverse range of test methods that have been described in the scientific literature for testing in vitro release of drug-releasing vaginal rings. Issues around in vitro-in vivo correlation and modelling of in vitro release data are also discussed.
Original languageEnglish
JournalJournal of Controlled Release
Early online date15 Oct 2019
Publication statusEarly online date - 15 Oct 2019


  • Dissolution testing
  • Release models
  • Novel dosage form
  • Sink condition
  • Controlled release
  • Sustained release
  • Intravaginal rings
  • In vitro release testing
  • in vitro - in vivo correlation


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