Ranitidine: Friend or Foe?
Ranitidine is a common medicine prescribed for acidity in the stomach. It is perhaps more widely known by its trade names, Rantac, Zantac etc. Now, this seemingly innocuous drug is in the news for all the wrong reasons. Why is there a lot of panic in the media about ranitidine causing cancer?
Ranitidine is scientifically an H2 (histamine-2) receptor blocker, which means that it decreases the amount of hydrochloric acid in the stomach. Ranitidine achieves this by blocking the parietal cells of the stomach, which are responsible for acid secretion. As a result, it relieves acidity. The invention of ranitidine is considered revolutionary, because it can be used to treat not only acidity, but also ulcers of the stomach and intestine. It is also used to treat H. pylori, a bacterial infection that can cause acid-reflux like symptoms and increase the risk of stomach cancer in future. Nowadays, surgeries for perforated stomach ulcers have become increasingly uncommon, because patients use ranitidine or similar drugs to prevent stomach ulcers from developing. Ranitidine is a cheap medicine, with each tablet costing around one rupee. It is currently in use in several countries around the globe. But why has this beneficial medicine been in news and been causing panic among the public?
On September, 13, 2019, the Food and Drug Administration (FDA) at the US on its press release, revealed that ranitidine tablets contain a chemical impurity called N-nitrosodimethylamine (NDMA) at low levels. NDMA is a known environmental contaminant found in water and foods, including meat, dairy products, and vegetables. It is formed during preparation of food, chlorination of water and in some industrial chemical reactions. Thus, the food we eat and water we drink invariably contain NDMA in minute quantities. Researchers have found that NDMA can cause liver cancer in mice. However, it is yet know if it can cause cancer in humans, but for the sake of safety, it has still been classified as a potential cancer causing agent. Whether or not a substance causes cancer depends also on the quantity of intake of the substance. It is very likely that NDMA can cause cancer if ingested in higher quantities. Therefore, governments have determined a safe limit of NDMA, above which the food becomes unsuitable for consumption.
How did NDMA come to exist in ranitidine tablets?
NDMA can form as an unintended by-product of industrial chemical reactions. When present in very small quantities, it is difficult to quantify and remove them. It is likely that NDMA was formed during one or more chemical reactions during the manufacturing process of ranitidine. In the past, when NDMA was found in other medicines, the whole batch of medicine was withdrawn from the market. This time, however, the amount of NDMA found in ranitidine tablets was in very minute quantities. Preliminary tests show that this amount barely exceeds the amount that is seen in common food stuffs. However, as an extreme measure of caution, many countries have banned and many pharmaceutical companies have withdrawn the medicine. However, the US FDA is evaluating whether such low levels of NDMA in ranitidine can cause any harm to the patients. FDA has not yet advised to stop using the medicine, but has suggested the patients to consider switching over to other medicines if they wish to discontinue ranitidine.