The efficacy and safety of Diclectin® (doxylamine/pyridoxine) for nausea and vomiting of pregnancy

Since the U.S. manufacturer's withdrawal of Bendectin® in 1981 due to the legal costs of defending against unwarranted court cases, Diclectin® (doxylamine succinate 10 mg/pyridoxine HCl 10 mg) is the only pharmacological treatment approved in North America for nausea and vomiting in pregnancy (NVP). Doxylamine, which is structurally related to histamine, possesses both antiemetic and anti-allergic effects. As vitamin B₆ requirements increase during pregnancy, pyridoxine, which also possesses antiemetic properties, provides supplementation that can prevent potential deficiency of this essential vitamin. A number of placebo-controlled clinical trials have documented the effectiveness of doxylamine and pyridoxine in combination in significantly reducing NVP. Recently, a comprehensive, prospective postmarketing study in Canada confirmed that drug efficacy in NVP does not diminish with longer-term (12-14 weeks') use of Diclectin®. This is one of the most extensively studied drug formulations of all time for use in pregnancy, with the great preponderance of evidence confirming its safety and a documented lack of any measurable teratogenic effects on the developing human fetus.