Pregnant women experiencing nausea and vomiting have a new treatment option, now that FDA has approved Diclegis® (doxylamine succinate and pyridoxine hydrochloride or vitamin B6) as the first drug approved for morning sickness in a half-century—a comeback for a drug withdrawn from the market 30 years ago.

Under its old trade name of Bendectin, Diclegis was pulled from market in 1983 after its manufacturer at the time, Merrell Dow, concluded the cost of defending the drug against lawsuits claiming birth defects would be too much to spend. Merrell Dow was not acting under FDA pressure, since the agency considered the drug safe and effective since approving it for market in 1956, and said as much in response to citizen petitions made to the agency at the time.

Later studies, however, found that Bendectin had not raised the ratio of 1 in 33 U.S. babies born with birth defects. In 2004, the American College of Obstetricians and Gynecologists issued guidelines calling the combination of Bendectin’s active ingredients a first-line therapy. Indeed for years, Diclegis’ Canadian maker Duchesnay has marketed a generic version of the drug in its home country.

Duchesnay said in a statement that Diclegis “is expected to be widely available in the U.S. by the end of May.”

Diclegis is intended for women who have not made adequate dietary and lifestyle changes to manage morning sickness—such as eating several small meals instead of three large meals, eating bland foods that are low in fat and easy to digest, and avoiding smells that can trigger nausea.

Unlike Bendectin, Diclegis has a coating for delayed-release to encourage women to take the tablet before experiencing nausea and vomiting, which affect 70% to 85% of pregnant women. The initial dose calls for two tablets to be taken at the start of treatment, once daily on an empty stomach. The dose can be increased to a maximum recommended four tablets daily—one in the morning, one mid-afternoon, and two at bedtime—if smaller doses do not adequately control morning sickness symptoms.

FDA approved Diclegis following a Phase III trial in which the drug was studied in 261 women experiencing nausea and vomiting due to pregnancy. Study participants were at least 18 years old and had been pregnant between 7 and 14 weeks. Women were randomly assigned to receive two weeks of treatment with Diclegis or a placebo.

Trial results showed that women taking Diclegis experienced greater improvement in nausea and vomiting than those taking placebo. More important, the study found that the combination of active ingredients in Diclegis did not pose an increased risk of harm to the fetus, allowing FDA to grant the drug the status of Pregnancy Category A.

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