In vitro modelling of in vivo discoloration of the dapivirine-levonorgestrel vaginal ring using a range of simulated vaginal and menstrual fluids

Clare F. McCoy, Diarmaid J. Murphy, Yahya H. Dallal Bashi, Peter Boyd, Pat Spence, Brid Devlin, Kyle Kleinbeck, Bindi Dangi, Tiffany Derrick, R. Karl Malcolm

Research output: Contribution to conferencePosterpeer-review

Abstract

Background
During clinical trials of the dapivirine+levonorgestrel (DPV+LNG) silicone VR, surface discoloration was observed on some ring samples. To investigate the potential causes of this discoloration, four different silicone VR formulations were exposed to SVF and SMF solutions for up to 60 days.

Methods
Placebo, 25mg DPV, 200mg DPV, and 200/320mg DPV+LNG silicone rings were prepared. SVF media containing either 20M H2O2, 20M H2O2 + copper IUD, methyl red, toluidine blue, or crystal violet were prepared, with SVF-only and ultrapure water as controls. SMF-based media (SMF-only, SMF+20M H2O2 or SMF+20M H2O2+IUD) were prepared using a 1:1 mixture of horse blood and SVF containing 0.5% w/v xanthan gum. Single rings were placed in 100mL of each media. Flasks were incubated (37oC/60rpm) for 30 and 60 days with media replenished weekly. At scheduled timepoints, rings were removed, rinsed, dried and photographed alongside controls. Cross-sections of VRs were examined for interior staining using microscopy.

Results
After 60 days, rings soaked in SVF-only, SVF+H2O2, SVF+H2O2+IUD media showed no surface discoloration. Rings soaked in SVF+dye media showed uniform surface staining. Methyl red and toluidine blue exposed rings showed significant colour ingression throughout the ring. Crystal violet exposed rings showed minimal colour ingression. After 60 days, the surfaces of all SMF-treated rings appeared yellow compared to controls. Colour intensity correlated with duration of SMF exposure. After 14 days, IUD-containing samples showed black/dark surface markings consistent with direct IUD contact. Additional non-uniform red-brown staining was observed on the surface of all rings exposed to SMF-only and SMF+H2O2 media and was demonstrated to be blood debris. No significant staining of the ring interior was observed.

Conclusion
SVF + dye media were shown to cause ring staining after 30 and 60-day exposure. Depending on the dye, either surface staining or complete dye ingression was achieved. Staining was also observed on rings exposed to SMF after 30 and 60 days. The yellowing of the ring with dark streaks and/or spots was consistent with the appearance observed in post-clinical use VRs. Discolorations were not deemed to be related to adverse events but may affect ring use behaviour.
Original languageEnglish
Publication statusAccepted - 05 Nov 2020
Event4th HIV Research for Prevention Conference (HIVR4P // Virtual) - Virtual
Duration: 27 Jan 202104 Feb 2021
https://www.hivr4p.org

Conference

Conference4th HIV Research for Prevention Conference (HIVR4P // Virtual)
Abbreviated titleHIV R4P
Period27/01/202104/02/2021
Internet address

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