Dextromethorphan - Extrapolation of findings from reproductive studies in animals to humans

QUESTION One of my patients, who is now 8 weeks pregnant, just read in the newspaper that dextromethorphan (DM), an antitussive found in a variety of cough medicines, caused birth defects in chicken embryos. The author of the study stated that even one dose could be dangerous and that he would never allow his wife to use this drug if she were pregnant. My patient was under standably very concerned because last week she was suffering from a nasty c ough and had been advised by her pharmacist to use a cough mixture containi ng DM, which she subsequently took for several days. ANSWER You may reassure your patient that she did not put her baby at risk by using this substance. Dextromethorphan has been on the market for many y ears and has never been implicated as a human teratogen. Furthermore, chick embryos are not a good model for predicting teratogenic potential in human s and, consequently, were abandoned as such more than 30 years ago.