It has been reported this week that the Medicines and Healthcare products Regulatory Agency (MHRA) has been asked to conduct a thorough review into the pregnancy drug Primodos, which is now the subject of huge media interest. Over the past 48 hours, news outlets have been awash with stories about new evidence unearthed in relation to the use of Primodos, any links its usage had with babies later born with significant birth defects and questions over whether a cover-up has occurred.

Primodos was a drug consisting of two hormone-based tablets which was widely prescribed to pregnant women in the 1960s and 1970s as a pregnancy test. It worked by inducing menstruation in women who were not pregnant, following the assumption that the high levels of progesterone found in the Primodos drugs would be absorbed into the body by pregnant women. However, it is alleged that use of this test led to women suffering instant miscarriages or giving birth to babies with significant deformities such as missing limbs, brain damage and heart defects. Various news outlets have now reported that one dose of Primodos equated to 13 morning-after pills or 40 oral contraceptive pills.

In 1975 a review by the Committee on Safety of Medicines concluded that the drug should not be used by pregnant women. A warning sign was placed on Primodos packets by the UK regulators that year, stating that the drug should not be taken during pregnancy because of a risk that it may cause malformations. Its manufacturer, Schering-Plough (later taken over by pharmaceutical giant Bayer), voluntarily discontinued production in 1978 for commercial reasons.

Attempts at prosecution

Following research conducted by a number of scientists, including Dr Isabel Gal, campaigners brought a case in the 1980s. However, the case was dropped after it was deemed unlikely that the claimants would be able to prove a direct causal link between Primodos and birth defects and the Legal Aid Board withdrew their public funding.

A review was also conducted in 2014 by the MHRA. This review included 36 existing studies, which had come up with varying conclusions. The review concluded that:

“The body of evidence for an association between HPTs and congenital abnormalities is mixed, with some studies finding a strong association, some finding a weak association and many others finding no association...Having carefully considered the available published evidence, our position therefore remains that the data is not sufficient to conclude that there is a causal association between the use of Primodos (or any HPT) and congenital abnormalities.”

The latest discovery

Papers were recently discovered by Marie Lyon, chair of the Association for Children Damaged by Hormone Pregnancy Tests, at the Berlin National Archives. Ms Lyon is one such individual who believes that the tablets that she was prescribed led to the deformities in her daughter, Sarah.

Significantly, among the 7,000 page stash of files included a study conducted by Professor William Inman, who was at the time a medical officer for the British Government. Dr Inman had concluded in 1975 that women who took a hormone-based pregnancy test were five times more likely to have a disabled child than those who did not. According to the files, Dr Inman’s research was passed to the manufacturing firm, so that it could “take measures to avoid medico-legal problems”. However, Dr Inman did not expressly recommend recalling the drug and the papers were later destroyed by him to prevent individual legal claims being brought against Schering-Plough based on his material.

What next?

Some newspapers have likened these developments to the Thalidomide scandal; a drug prescribed between 1958 and 1961 to combat morning sickness. It was later found that the drug led to the birth of children with large disfigurements, including missing or deformed arms and legs and resulted in a large compensation pay-out by the UK Government.

Bayer has maintained that the use of Primodos was “in compliance with prevailing laws” at the time. It has similarly noted that the “evidence for a causal association between the use of hormonal pregnancy tests and an increased incidence of congenital malformations was extremely weak” and has denied that any documents have been concealed.

Following the news that the MHRA would conduct a review into Primodos, junior health minister James O’Shaughnessy has stated:

“I welcome this investigation – it’s vital that we take concerns such as these seriously. That’s why we’ve asked the medicine and healthcare products regulatory agency to conduct a thorough scientific review of the evidence on the issue.”

It remains to be seen whether this latest discovery will give rise to a new legal challenge. An important factor to consider will be not only to what extent the manufacturer was aware of any potential medical issues, but also to what extent tests were carried out both prior to Primodos’ distribution and following the study conducted by Dr Inman.

Bayer argue that since the discontinuation of the 1982 claim, there has been no new scientific knowledge to confirm a causal link between the use of Primodos and the occurrence of congenital abnormalities. However, Ms Lyons and other affected families remain hopeful that a claim against Bayer, and potentially the British government, could be a possibility once again.