emergency contraception effectiveness overestimated Stanford, emergency contraception mechanism of action levonorgestrel, Stanford JB emergency contraception clinical pharmacology critique, Plan B efficacy expectations post-coital contraception, emergency contraception pregnancy prevention effectiveness evidence, morning after pill overestimated effectiveness analysis, emergency hormonal contraception population level impact, post-coital contraception questionable expectations review, levonorgestrel emergency contraception real world effectiveness, emergency contraception ovulation fertilization implantation mechanism
PMID 18030305 18030305 DOI 10.1038/sj.clpt.6100442 10.1038/sj.clpt.6100442
Cite this article
Stanford, J. B. (2008). Emergency contraception: overestimated effectiveness and questionable expectations. Clinical pharmacology and therapeutics, 83(1), 19-21. https://doi.org/10.1038/sj.clpt.6100442
Stanford, J. B. "Emergency contraception: overestimated effectiveness and questionable expectations." Clinical pharmacology and therapeutics, vol. 83, no. 1, 2008, pp. 19-21.
Related articles
Contraception/ComparisonMechanism of ActionEffectiveness AnalysisPostfertilization Effects
To model the effectiveness that can be obtained if levonorgestrel-only emergency contraception (EC) acts only through disrupting ovulation, in relation to other effects that may occur before or after fertilization and accounting for delays in administration. We modeled follicular growth as a function of follicular size, using known day-specific probabilities of conception and known disruption of ovulation by levonorgestrel-only EC, to estimate the expected effectiveness of EC. Combined data from multiple clinical studies. PATIENT(S): Simulation models. INTERVENTION(S): Disruption of ovulation. MAIN OUTCOME MEASURE(S): Effectiveness in the form of proportion of pregnancies prevented. RESULT(S): With disruption of ovulation alone, the potential effectiveness of levonorgestrel EC ranged from 49% (no delay) to 8% (72-hour delay). With complete inhibition of fertilization before the day of ovulation, the potential effectiveness of levonorgestrel EC ranged from 90% (no delay) to 16% (72-hour delay). CONCLUSION(S): The gap between effectiveness of levonorgestrel EC estimated from clinical studies and what can be attributed to disruption of ovulation may be explained by overestimation of actual effectiveness and supplementary mechanisms of action, including postfertilization effects. Additional data with follicular ultrasound and precise measures of delay between intercourse and EC administration would yield greater insight into effectiveness and mechanisms of action.
AndrologyACE Inhibitors for OligospermiaIdiopathic Oligospermia TreatmentMale Infertility
The outcomes of drug treatment for male infertility remain conjectural, with controversial study results. Our pilot study employed a randomized, placebo-controlled, crossover methodology with intention-to-treat analysis. Thirty-three men with idiopathic oligospermia were randomized to start either daily oral lisinopril 2.5 mg (n = 17) or daily oral placebo (n = 16). Lisinopril was found to cause a normalization of seminal parameters in 53.6% of the participants. Although the mean ejaculate volume was unchanged (P ≥ 0.093), the total sperm cell count and the percentage of motile sperm cells increased (P ≤ 0.03 and P < 0.001, respectively), whereas the percentage of sperm cells with abnormal morphology decreased (P ≤ 0.04). The pregnancy rate was 48.5%, and there was no serious adverse drug event. It is concluded, albeit cautiously, that prolonged treatment with 2.5 mg/day of oral lisinopril may be well tolerated in normotensive men with idiopathic oligospermia, may improve sperm quantity and quality, and may enhance fertility in approximately half of those treated.
Atkinson RL et al., 1985·Clinical Pharmacology and Therapeutics
The endogenous opiate system is thought to be associated with the regulation of food intake and body weight. Opiate antagonists decrease food intake in animals, but there are no controlled studies in obese man to evaluate body weight response to naltrexone. Sixty obese people were randomized into three groups and given 0, 50, or 100 mg of the opiate antagonist naltrexone for 8 weeks in an outpatient, double-blind study. Weight loss was not significant in either the 50 or 100 mg groups as compared with placebo. However, when broken down by sex, women had a significant (P less than 0.05) weight loss of 1.7 kg, while men did not lose weight. Side effects were modest, but six subjects had one or more abnormal liver function test results; in one subject these abnormalities appeared to be clinically significant. The effects of naltrexone on weight loss were less than expected in light of prior animal studies, but further studies with a wider dose range of naltrexone may be indicated.