Measuring true contraceptive efficacy. A randomized approach--condom vs. spermicide vs. no method.

No investigator has attempted to measure prospectively the true efficacy of a contraceptive method, compared with a control group using no method, because contraceptive trials focus on women trying to avoid pregnancy and ethical concerns do not permit the withholding of contraception. We tested the feasibility of an approach that recruited women who desired pregnancy but were willing to postpone conception by 1 month. In this protocol, we restricted frequency and timing of intercourse to one coital act on the most fertile day of the menstrual cycle, as measured by a luteinizing hormone (LH) detection kit. Participants were randomized to use either a male latex condom, spermicidal film, or no method. In this feasibility study we recruited 58 women at three sites, with one site recruiting 25 women in 5 months. Among 54 women who completed the study, we found a 12% pregnancy rate for the group using no method (2/17; 95% confidence interval [CI], 1-36%) and an 11% pregnancy rate for the group using spermicidal film (2/18; 95% CI, 1-35%). No pregnancies occurred among the 19 women using condoms (0/19; 95% CI, 0-18%). The wide confidence intervals illustrate the small sample size of this pilot study and no conclusions can be drawn about the relative efficacy of the methods. Having demonstrated the feasibility of this study design, we now urge the initiation of a large-scale study to evaluate the efficacy of barrier methods using our randomized approach, with a control arm using no method of contraception.

Effects of storage and temperature upon soft jelly capsules containing nonoxynol as spermicide.

Recently, adverse effects of long periods of storage and high temperature on physical characteristics of the soft jelly capsule wall were observed. In the present study, the effects of both parameters upon the mean rupture time of the capsule, and the release of the active compound were evaluated in vivo in 40 women. The results disclosed that the storage for long time and the exposure of the capsules to high temperatures, delays significantly the mean rupture time and the release of the active compound. A rapid distribution, adequate storage, as well as a delay of intercourse after vaginal insertion of the device are suggested.

PIP: In Coahuila, Mexico, 20 women vaginally inserted soft jelly capsules containing the spermicide nonoxynol-9 which had been stored for 90 days at 25-30 degrees Celsius (group I), and 20 more women inserted capsules of the same type which had been stored in an incubator for 90 days at 45 degrees Celsius (group II). All 40 women inserted the capsules during days 12-14 of the menstrual cycle to avoid physiological changes of vaginal humidity during the cycle. At the end of each study period (2-13 minutes), rupture/nonrupture and weight of the capsules were recorded. A loss of more than 15% of the capsule's weight constituted release of nonoxynol-9. The time for the capsule to rupture ranged from 4 to 12 minutes for group I and from 6 to 13 minutes for group II. The mean rupture time was greatest for those capsules stored at the higher temperature (i.e., group II) (10.2 vs. 5.6 minutes; p 0.001). The mean release time was also greatest for group II (12.1 vs. 6.7 minutes; p 0.02). Thus, long storage and high temperature delayed the minimum time for capsule rupture in the vagina by 4-6 minutes. Capsules stored for a long time and at a high temperature had a higher wall consistency than their counterparts. Capsules stored at a high temperature had a harder consistency than those stored at a lower temperature. These findings suggest the need to rapidly distribute capsules, to store them under controlled temperature, and to delay intercourse after insertion for more than 10 minutes.