Comparative spermicidal performance of iodinated and non-iodinated contraceptive formulations of nonoxynol-9 co-precipitated with polyvinylpyrrolidone.

ABSTRACT

The objective of this study was to evaluate the spermicidal qualities of various combinations of nonoxynol-9 (N-9; whole molecule = oligomers 1-18) and its isolated fractions (oligomers 8-10, 4-6 and 1-3), co-precipitated with non-iodinated and/or iodinated (Io) polyvinylpyrrolidone (PVP) as possible vaginal contraceptives. Spermicidal qualities of known equimolar concentrations of various combinations of PVP/N-9 and PVP-Io/N-9 were tested via a modified Sander-Cramer test (SCT) using human spermatozoa. Spermicidal agents and semen samples were mixed 11 (v/v) and evaluated for sperm viability. Spermicidal activity was reported as the minimal concentration (microgram/mL) of spermicide capable of killing all spermatozoa within 20 sec after exposure to the spermicide. The spermicidal activity of PVP/N-9 and PVP-Io/N-9 preparations containing N-9 oligomers 1-18 and/or 8-10 was similar, and these preparations were more efficient in killing the spermatozoa than the ones containing N-9 oligomers 4-6 and 1-3. Polyvinyl-pyrrolidone proved to be an effective vehicle for PVP/N-9 and PVP-Io/N-9 preparations, especially those containing N-9 oligomers 4-6 and 1-3. Incorporation of Io into the spermicidal preparations brought about additional efficacy. The current findings could be of clinical significance in future studies when preparing and delivering those selected co-precipitates vaginally.

ABSTRACT

PIP At the University of Kentucky in Lexington, pooled normospermic semen specimens collected after 3-4 days of sexual abstinence were co-precipitated with non-iodinated and/or iodinated (Io) polyvinylpyrrolidone (PVP) to determine the spermicidal qualities of various combinations of nonoxynol-9 (N-9) (oligomers 1-18) and its isolated fractions (oligomers 8-10, 4-6, and 1-3) as possible vaginal contraceptives. The Sander-Cramer test on human spermatozoa was used to test the spermicidal qualities of known equimolar concentrations of various combinations of PVP/N-9 and PVP-Io/N-9. The minimal lethal dose (LD) concentration (mcg/ml) of spermicide capable of killing all spermatozoa within 20 seconds after exposure to the spermicide was the definition of spermicidal activity. The LD of PVP/N-9 and PVP-Io/N-9 spermicidal preparations containing N-9 oligomers 1-18 and/or 8-10 was similar (165-166/mcg/ml for PVP/N-9 and 193-231/mcg/ml for PVP-Io/N-9). These particular preparations were more efficient in destroying spermatozoa than those containing N-9 oligomers 4-6 and 1-3 (p 0.05). PVP appeared to an efficient vehicle for the studied spermicides, particularly those containing N-9 oligomers 4-6 and 1-3. The addition of Io into PVP/N-9 preparations improved spermicidal activity, and significantly so, for N-9 oligomers 4-6 and 1-3 (495 mcg/ml for non-iodinated PVP/N-9 vs. 385 mcg/ml for PVP-Io/N-9; p 0.05). These findings will help future studies when the researchers prepare and deliver spermicides that co-precipitate vaginally.