The use of
microbicides is a promising approach for the prevention of HIV-1 transmission. Unfortunately, various candidates failed in clinical trials. In some cases, the candidate
microbicide even resulted in enhanced virus transmission. Therefore, there is an urgent need to develop more predictive preclinical strategies to anticipate the in vivo efficiency/toxicity rate, including in vitro assays that evaluate effects on epithelial integrity and
inflammation. The present study aims to identify potential safety issues concerning the use of
microbicides and
excipients commonly used in vaginal
microbicide preparations. The toxicities of various
active pharmaceutical ingredients (APIs;
TMC-120,
UC-781,
tenofovir [PMPA],
PRO-2000, and
glycerol monolaurate [GML]) and
excipients (preservatives, cosolvents,
surfactants, and
cyclodextrins) were evaluated using an in vitro dual-chamber model and uterine cervical explants. Epithelial viability and permeation of fluorescent virus-sized beads, as well as induction of
interleukin-8 (IL-8; as a sensitive marker of an inflammatory response), were assessed. Surprisingly, cell viability and epithelial layer integrity were compromised by most
excipients at concentrations near the typical concentration used in
vaginal gels, and a significant increase in the production of
IL-8 was observed at subtoxic concentrations. Within the APIs,
TMC-120,
UC-781, and PMPA showed higher selectivity indices than
PRO-2000 and GML. In conclusion, identification of safety issues concerning the use of pharmaceutical
excipients could help to formulate less toxic vaginal
microbicide preparations.