Effects of cholic acid and "Protectaid" formulations on human sperm motility and ultrastructure.

Cholic acid (sodium cholate) and the other active ingredients of F-5 gel preparations in use for the impregnation of a new vaginal sponge (Protectaid) with contraceptive and anti-sexually transmitted disease properties were assessed for their effects on human sperm motility and ultrastructure. Cholic acid (CA) produced an inhibition of motility which was both dose- and time-dependent. A complete suppression of motility was obtained at 30 seconds by a CA concentration of 1.25%. Nonoxynol-9 (NX9) compared with benzalkonium chloride (BZC) showed no significant difference at the concentration required (0.025%) to give a total inhibition of sperm motility after exposure for 30 seconds. The addition of F-5A gel containing 0.5% of each one of the spermicide ingredients (CA NX9 and BZC) produced a total suppression of sperm motility within 30 seconds at a dilution of 1/50. Another preparation F-5B gel containing the spermicide ingredients at different concentrations (1.25% CA 0.125% NX9 and 0.05% BZC) produced this same effect with a 1/10 dilution. Exposure of semen to a CA concentration of 1.25% or to 1/10 dilutions of F-5A gel for 30 seconds led to profound changes of sperm ultrastructure studied by scanning (SEM) and transmission (TEM) electron microscopy. SEM and TEM findings indicate that CA acts as a spermicide through its natural detergent properties damaging the outer plasma membrane of sperm cells. Protectaid formulations affect sperm motility and viability in a similar way. (authors)