Pyridoxine-Doxylamine: Questioning the Efficacy of a Commonly Used Morning Sickness Drug

Highlights

• Nausea during the first trimester of pregnancy is referred to morning sickness.
• Pyridoxine-doxylamine drug is an antihistamine drug used for the treatment of morning sickness.
• An unpublished research questions the efficacy of a commonly used pyridoxine-doxylamine drug for morning sickness.

The efficacy of the commonly used pyridoxine-doxylamine medication for nausea during pregnancy was questioned in an unpublished research carried out by the Merrell-National Laboratories in 1970. The 40 year old research study is now published in the PLOS One journal.

The study was published by Dr. Nav Persaud, family physician, research scientist at St. Michael’s Hospital, restoring invisible and abandoned trials (RIAT) initiative which has unpublished studies that are difficult to determine the treatment options.

Pyridoxine-doxylamine drug sold under the name Diclectin was tested for its efficacy to treat morning sickness in the first trimester of pregnancy.

Even though the results of the clinical trial was not published, regulatory bodies like Health Canada and the United States Food and Drug Administration (USFDA) has collected information to approve the drug.

Around 33 million women in the world are prescribed with pyridoxine-doxylamine drug.

According to the Society of Obstetricians and Gynecologists of Canada, the drug is considered to be a standard of care for women with nausea and vomiting "since it has the greatest evidence to support its efficacy and safety."

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Dr. Persaud, said, even though there are many flaws in the study which call questioning on why the study was not published, He had collected about 36000 pages of documents from the FDA and Health Canada about the topic.

Clinical Trial
The clinical trial was conducted on 2308 pregnant women who were experiencing nausea and vomiting. The data was collected from 14 clinics in the United States. These women were divided into eight groups, out of which one received placebo and other seven groups received combination of drugs.

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The research data was collected from 1600 participants and proportion of data collected from the seven groups who received combination of drugs were found to evaluate as moderate or excellent when compared to those who received placebo.

Dr. Persaud’s Conclusions

• No availability of the final study results.
• Even though the trial lasted for a week, there was an increased number of participants who did not complete it.
• Physicians did not score the symptoms clearly.
• Data was unavailable for 37% of patients in the placebo group
• Unable to contact the researchers since most of them had died
• Data collected from 30patients were excluded due to an order of the Commissioner of Food and Drugs in a 1975 letter which stated“ data recording in absence of patient visits”.

Morning Sickness
Nausea that occurs during the first trimester of pregnancy is referred to as Morning Sickness.

Around 7 in 10 women experience morning sickness during pregnancy.

Morning sickness which sometimes requires hospitalization may be called Hyperemesis gravidarum.

Symptoms of Morning Sickness

• Nausea
• Vomiting
• Anxiety and depression
• Loss of appetite

Pyridoxine - Doxylamine Drug
Doxylamine is a sedative antihistaminic drug which is marketed along with pyridoxine for the treatment of morning sickness.

Side Effects of Pyridoxine-Doxylamine

• Dry mouth
• Drowsiness
• Abdominal Upset
• Vertigo

Source-Medindia