pharmaceutics Review The Vaginal Microbiota, Bacterial Biofilms and Polymeric Drug-Releasing Vaginal Rings Louise Carson 1, Ruth Merkatz 2, Elena Martinelli 2, Peter Boyd 1, Bruce Variano 2 , Teresa Sallent 2 and Robert Karl Malcolm 1,* 1 School of Pharmacy, Queen’s University Belfast, Belfast BT9 7BL, UK;
[email protected] (L.C.);
[email protected] (P.B.) 2 Population Council, One Dag Hammarskjold Plaza, New York, NY 10017, USA;
[email protected] (R.M.);
[email protected] (E.M.);
[email protected] (B.V.);
[email protected] (T.S.) * Correspondence:
[email protected] Abstract: The diversity and dynamics of the microbial species populating the human vagina are increasingly understood to play a pivotal role in vaginal health. However, our knowledge about the potential interactions between the vaginal microbiota and vaginally administered drug delivery systems is still rather limited. Several drug-releasing vaginal ring products are currently marketed for hormonal contraception and estrogen replacement therapy, and many others are in preclinical and clinical development for these and other clinical indications. As with all implantable polymeric devices, drug-releasing vaginal rings are subject to surface bacterial adherence and biofilm formation, mostly associated with endogenous microorganisms present in the vagina. Despite more than Citation: Carson, L.; Merkatz, R.; 50 years since the vaginal ring concept was first described, there has been only limited study and Martinelli, E.; Boyd, P.; Variano, B.; reporting around bacterial adherence and biofilm formation on rings. With increasing interest in the Sallent, T.; Malcolm, R.K. The Vaginal vaginal microbiome and vaginal ring technology, this timely review article provides an overview Microbiota, Bacterial Biofilms and of: (i) the vaginal microbiota, (ii) biofilm formation in the human vagina and its potential role in Polymeric Drug-Releasing Vaginal Rings.