The present invention provides a delivery system for the intravaginal administration of prophylactic and therapeutic agents. In one embodiment, the invention provides a pH-responsive, biocompatible film for intravaginal administration of a beneficial agent, comprising a biocompatible, hydrophilic polymer that is positively charged at a first pH and in electronically neutral form at a higher pH; an effective amount of a beneficial agent; and, optionally, at least one film-forming binder. The pH responsive film may also include other additives such as plasticizers, sustained release polymers, antioxidants, and antimicrobial agents. In another embodiment, the pH-responsive film of the present invention comprises a laminated composite of (a) a bioadhesive layer that serves to affix the film to a mucosal surface within the vagina and, laminated thereto, (b) at least one reservoir layer comprising at least one beneficial agent and a biocompatible hydrophilic polymer. The pH responsive films of the present invention can be used for contraception, treatment and/or prevention of viral infections, treatment of vaginal infections, relief of vaginal itch, vaginal cleansing, and enhancement of vaginal lubrication.