A US scientist reported last week on research indicating that nifedipine might interfere with male fertility and hence might have potential use as a male contraceptive. The research was presented at a meeting of the American Society of Reproductive Medicine. In response, Bayer (manufacturer of Adalat) said that there had been reports since the late 1980s on nifedipine's effects on sperm. There were no data available on the prevalence of infertility in patients taking calcium channel blockers. The company said that in 1993 the potential use of nifedipine as a male contraceptive was assessed. However, it decided not to pursue this work "since available data suggest that nifedipine does not inhibit fertilisation in a substantial proportion of patients."