Assessment of new formulations of nonoxynol-9 coprecipitated with polyvinylpyrrolidone and iodine as possible vaginal contraceptives.

Objective: To assess the in vitro spermicidal activity of new formulations of nonoxynol-9, coprecipitated with polyvinylpyrrolidone (PVP) or iodinated PVP, against human spermatozoa via the use of the Sander-Cramer test and the cervical mucus penetration test.

Design: Solutions of PVP-nonoxynol-9 and iodinated PVP-nonoxynol-9 containing nonoxynol-9 whole molecule (oligomers 1 to 18) and its isolated fractions (oligomers 8 to 10, 4 to 6, and 1 to 3) at various concentrations (microgram/mL) were prepared via serial dilutions. Spermicidal solutions were mixed with human semen to determine the minimal lethal dose (microgram/mL). In the Sander-Cramer test, the lethal dose was reported as the minimal dose capable of killing spermatozoa within 20 seconds. In the cervical mucus penetration test, the lethal dose was reported as the minimal dose capable of preventing penetration of spermatozoa into cervical mucus beyond the second millimeter length of the capillary.

Setting: Andrology laboratory, University of Kentucky, Lexington, Kentucky.

Patient(s): Normospermic male donors.

Main Outcome Measure(s): Spermicidal lethal dose determination of various nonoxynol-9 preparations containing the whole nonoxynol-9 molecule and its isolated fractions coprecipitated with PVP or iodinated PVP.

Result(s): The use of PVP increased the aqueous solubility of the nonoxynol-9 formulations containing oligomers 1 to 18 and 8 to 10 slightly. The coprecipitation of the nonoxynol-9 formulations containing nonoxynol-9 oligomers 4 to 6 and 1 to 3 with PVP significantly increased their solubilization and spermicidal action in vitro. Moreover, the incorporation of iodine significantly decreased the minimal nonoxynol-9 dose required for complete killing of spermatozoa in preparations containing nonoxynol-9 oligomers 4 to 6 and 1 to 3.

Conclusion(s): Incorporation of all three components tested in this study (PVP, nonoxynol-9, and iodine) enhanced the efficiency of the spermicidal preparations, especially for nonoxynol-9 preparations containing nonoxynol-9 oligomers 4 to 6 and 1 to 3.