Lorna Kemble Pregnancy and Birth

2413 Other agents with antiemetic properties

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Pharmacology and toxicology

With respect to the antiemetics such as alizapride and aprepitant, used primarily in oncology, there is insufficient experience to estimate prenatal risk.

Betahistine, a histamine analog, and the antihistamines cinnarizine and flimarizin have long been in use, and no increase in birth defects after clinical use has been shown. However, the absence of controlled studies on the use of these agents during pregnancy argues against their routine use. Betahistine and cinnarizine are both effective for treatment of vestibulair vertigo, as in Meniere's syndrome.

Scopolamine is a parasympatholytic used transdermal^ in patch form as antiemetic treatment. Among 309 pregnant women exposed to scopolamine in the first trimester, no increase in the rale of birLli defects was seen (Heinonen 1977). Other studies have also given no indication of an increase in birth defects after clinical use. Scopolamine crosses the placenta, and can cause anticholinergic symptoms such as tachycardia and decreased heart rate variability in the fetus. This effect could, at least theoretically, interfere with the detection of hypoxia-induced fetal bradycardia.

Recommendation. Betahistine, cinnarizine, flunarizin, scopolamine, and, most particularly, alizapride and aprepitant should only be used when those substances recommended in the previous sections have failed. The use of any other antihistamine or antiemetic is not, in itself, an indication either for invasive diagnostic procedures or for termination of pregnancy.