Evaluation of poly(styrene-4-sulfonate) as a preventive agent for conception and sexually transmitted diseases

A commercial preparation of a sodium polystyrene sulfonate (designated as N-PSS; its molecular weight is 500 000 daltons) was tested as an inhibitor of sperm function and as a preventive agent for conception and the transmission of sexually transmitted diseases. The polymer is an irreversible inhibitor of hyaluronidase and acrosin; its IC₅₀ values are 5.7 μg/mL and 0.5 μg/mL, for hyaluronidase and acrosin, respectively. N-PSS is also a stimulus of human sperm acrosomal loss. It produces maximal acrosomal loss at 2.5 μg/mL. Contraception in rabbits is nearly complete when rabbit spermatozoa are pretreated with 0.5 mg/mL of N-PSS before artificial insemination; however, N-PSS does not immobilize spermatozoa at concentrations as high as 50 mg/mL. N-PSS has broad spectrum antiviral and antibacterial activities. Infection by human immunodeficiency virus and herpes simplex virus are inhibited by N-PSS; 3-log reductions are produced by 7 μg/mL and 3 μg/mL, respectively. N-PSS is active against Chlamydia trachomatis and Neisseria gonorrhoeae. At 1 mg/mL, N-PSS inhibits chlamydial infectivity by more than 90%. N-PSS produces a 3-log reduction in gonococcal growth at 15 μg/mL. In contrast, N-PSS (5 mg/mL) does not affect the growth of Lactobacillus (normal component of the vaginal flora). N-PSS can be classified as a noncytotoxic contraceptive antimicrobial agent. These properties justify bringing a polystyrene sulfonate into clinical trials for its evaluation as a preventive agent for conception and several sexually transmitted diseases.