Mechanisms of action of currently available woman-controlled, vaginally administered, non-hormonal contraceptive products

Woman-controlled, vaginally administered contraceptives offer women discreet, self-administered, and reversible options. This brief report summarizes the mechanisms of action (MOAs) of currently available, woman-controlled, vaginally administered, non-hormonal products, excluding those that need to be fitted by a healthcare provider. MOAs of three general types of contraceptives will be reviewed, including pH modulators, spermicides, and barrier methods. The recently approved vaginal pH modulator (lactic acid, citric acid, and potassium bitartrate) has a non-hormonal MOA, acting as a buffering agent in the presence of alkaline semen and resulting in sperm immobilization. In contrast, spermicides, such as nonoxynol-9, act by lysing sperm membranes, resulting in sperm death. Barrier methods, such as the diaphragm and female condom, prevent sperm from entering the uterus. In addition to their varying MOAs, each woman-controlled, vaginally administered method has different instructions for use, efficacy, side effects, and availability/insurance coverage, thus providing a range of characteristics to fit different needs and preferences.