Popular morning sickness drug 'ineffective,' study reveals By Yella Hewings-Martin PhD

Morning sickness can put a real strain on pregnant mothers. And when diet or non-medicinal treatments fail, a drug that contains doxylamine and pyridoxine is often prescribed. However, the drug's effectiveness has been called into question.

In 2017, researchers working at the University of Toronto in Canada and the Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, also in Toronto, Canada, reanalyzed a pivotal doxylamine and pyridoxine clinical trial from the 1970s and made a fairly surprising finding: the data had substantial flaws.

Digging even deeper, Dr. Navindra Persaud — from the Department of Family and Community Medicine at St. Michael's Hospital as well as the Department of Family and Community Medicine at the University of Toronto — and colleagues reanalyzed another clinical trial using an updated version of the drug, this one from 2010.

The recent trial was part of the reason that the Food and Drug Administration (FDA) approved the popular morning sicknessdrug known as Diclegis.

Commenting on his findings, Prof. Persaud told me, "The medication seems to be ineffective based on the results of this trial. I was shocked to learn this about a commonly prescribed medication."

The results of Prof. Persaud's analysis are now published in the journal PLOS ONE.

'Only FDA-approved' morning sickness drug

Diclegis is the only drug approved by the FDA for the treatment of morning sickness in pregnancy. According to its manufacturer Duchesnay, it has been prescribed to 33 million women worldwide.

In Canada, where the drug is known as Diclectin, it is prescribed at least once for every two births.

I asked Prof. Persaud why he decided to look into the drug. "I used to prescribe this medication," he explained. "I was taught to prescribe it. The medication was recommended as the first line medication for nausea and vomiting during pregnancy."

"When I looked carefully at the clinical practice guidelines that recommended this medication, they did not cite supporting studies. So I tried to find the basis for the recommendations. It was surprisingly difficult to obtain information about this commonly prescribed drug."

Prof. Navindra Persaud

When the results of the clinical trial were initially published in the American Journal of Obstetrics & Gynecology in 2010, the study authors concluded, "Diclectin [...] is effective and well-tolerated in treating nausea and vomiting of pregnancy."

Drug 'significantly better than placebo'

The study involved 261 pregnant women, all of whom completed a 2-week course of daily Dicletin or placebo treatment. As the authors explained in the paper, "Diclectin led to significantly greater improvement in NVP [nausea and vomiting of pregnancy] symptoms as compared with placebo."

This was based on a drop in what is known as the PUQE score. PUQE stands for pregnancy-unique quantification of emesis/nausea, with a score of 3 meaning no symptoms and a score of 15 being the most severe.