In Vitro Surfactant Structure-Toxicity Relationships: Implications for Surfactant Use in Sexually Transmitted Infection Prophylaxis and Contraception

Background The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs) makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. Methodology/Principal Findings We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants – nonionic (Triton X-100 and monolaurin), zwitterionic (DDPS), anionic (SDS), and cationic (CnTAB (n = 10 to 16), C12PB, and C12BZK) – were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC) suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C12PB and C12BZK, does not justify their use as contraceptive agents. C12PB and C12BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations. Conclusions/Significance Our results contribute to understanding the mechanisms involved in surfactant toxicity, have a predictive value with regard to their safety, and may be used to design more effective and less harmful surfactants for use in topical applications for STI prophylaxis.Foundation for Science and Technology of the Portuguese Ministry of Science and Higher Educatio

Review Update on Topical Therapy for Psoriasis

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Purpose of Review: Studies show frequent usage but low adherence rates and poor satisfaction from topical therapy for psoriasis. These were attributed to low efficacy, inconvenience of application, and poor cosmetic quality for different body parts. Recent Findings: Multicenter surveys on patients suggest a two-way holistic approach, where patients convey what bothers them most and doctors explain how products address specific concerns. New rapid response targeted topical agents, in cosmetically acceptable preparations, applied less often, are undergoing efficacy and safety studies, ideally on large populations up to 1 year or more. Until available, this review addresses gaps in knowledge on how to maximize effects of emollients, used alone, with physiologic lipids, or as base for active topical therapy. Summary: Updates—on how psoriasis skin becomes itchy, red, dry, thick, and scaly from inflammation and barrier defects—explain clinical responses to the physical, chemical, and functional properties of psoriasis topical therapies