Despite being prescribed for pregnant women for over 40 years, a new study that looked at the trial on which the effectiveness of the drug, Diclectin, found the original trial’s outcome was based on flawed research, according to a story in the Washington Post.

Researchers in Toronto poured over the 7,200 pages from a clinical trial performed back on the 1970s, official records from the trial that until now had never been made public.  The information was finally released from the Food and Drug Administration (FDA) through the Freedom of Information Act, and was obtained as part of a worldwide effort to research earlier trials that may not have been published to the public, or had been abandoned.

The trial in question was conducted by the now-defunct Merrell-National Laboratories, and involved some 2,300 patients in 14 separate clinics in the United States who were experiencing nausea and vomiting during the first 12 weeks of pregnancy.

Nav Persaud, the main author on the new analysis, and a family physician at St. Michael’s Hospital, said the trial was the key to getting approval of the drug in Canada, despite the fact that the study was never completed.  Persaud also said the original study contained critical flaws, and some of the information that was supposed to be obtained from the patients was incomplete.

Persaud added the study failed to obtain follow up information on about a third of the patients. despite the fact the trial only lasted for about a week.

Ron Vaillancourt, a spokesman for Duchesnay, which sells the drug in Canada defended the drug citing 16 cohort studies, two meta-analyses. an ecological study, a neurological development study and a number of other studies that support the use of the pharmaceutical.

“We have complete confidence in the safety and efficacy of Diclectin and are very proud to provide it as a safe and effective treatment option for women suffering from nausea and vomiting of pregnancy,” he told the Washington Post.

Still, Persaud said he is no longer prescribing the drug for his patients, and calls for the medication to be reviewed by the FDA and Health Canada.

“I’ve been looking into this [for the] last five years and found no good reason to prescribe this medication over others. Astonishingly, I’ve found the study that is supposed to be the basis of the claim this medication is effective is problematic,” continued Persaud.

The drug is sold in the US as Diclegis.

The researchers published their findings in PLOS One on Wednesday of this week.