A new report published in the journal Plos One is critical of a 1970s study used to approve a commonly prescribed morning sickness drug, saying the study contains serious flaws.
The drug in question is sold under the name Diclectin in Canada and Diclegis in the United States and is essentially composed of two other drugs: pyridoxine, otherwise known as vitamin B6, and doxylamine, a medication found in over-the-counter sleep aids. In Canada, Diclectin is reportedly prescribed by physicians at a rate of one prescription for every two live births, while in the United States, Diclegis has been taken by an estimated 35 million pregnant women -including, assumingly, reality TV star Kim Kardashian, who in 2015 posted an Instagram in praise of the drug.
With these numbers, the supporting data on the drug should be conclusive and rigorous, yet the authors of the new report argue that a 1970s supportive study should not be included to back the drug.
“While the analyzed data indicate differences from placebo for several combinations, the questionable data integrity, high drop-out rate, and other methodological concerns mean that the prescribing of this medication should not be based on this trial,” say the report’s authors, Rujun Zhang of the Department of Family and Community Medicine at the University of Toronto and Navindra Persaud at the Keenan Research Centre of the Li Ka Shing Knowledge Institute at St. Michael’s Hospital in Toronto.
The report’s authors made freedom of information requests to the FDA, Health Canada and the European Medicines Agencies, producing 7,200 pages of information from the FDA on the drug trial and a further 359 pages from Health Canada, 212 pages of which had been redacted.
The researchers raise a number of concerns about the study, including claims of unclear research methods, missing information, data integrity issues and risk of bias. “No firm conclusion about the efficacy or safety of doxylamine or pyridoxine can be drawn from the limited available information,” say the study’s authors.
In speaking to the Toronto Star about his co-authored report, Persaud said, “We reviewed the available information and found some potential problems with the study that doctors and patients should know about. Regulators can make better decisions when this information is publicly available.”
Other members of the medical community have weighed in. Dr. Siripanth Nippita, researcher at Harvard Medical School said, “Studies that have been done since this trial was completed in the 1970s show that doxylamine and pyridoxine are an effective treatment for nausea and vomiting in pregnancy.”
Health Canada was contacted by the Toronto Star and responded by saying the drug was reassessed in 1989 and again reviewed by an expert panel just last year, along with submissions from the drug maker that show the positive effects of its use. “The available evidence continues to support Diclectin in the treatment of nausea and vomiting during pregnancy,” said the Health Canada spokesperson.
As reported by NPR, the American Congress of Obstetricians and Gynecologists advises that women experiencing nausea and vomiting during pregnancy should first try lifestyle and diet changes such as taking a multivitamin, eating dry toast or crackers in the morning and drinking plenty of fluids. For cases where these changes do not alleviate symptoms or in the case of severe nausea and vomiting during pregnancy, the ACOG says that both vitamin B6 and doxylamine have been found to be safe to take during pregnancy.