Zantac is one of the most widely used H2 receptor blocker antacids

A few weeks ago I wrote about the dangers of taking PPIs long term, now it is H2 receptor blockers that are coming under the spotlight. Both PPIs and H2 receptor blockers are among the most widely taken drugs worldwide and both are taken to combat heartburn and indigestion, i.e. as antacids. Along with the more traditional neutralising antacids, such as magnesium hydroxide, both PPIs (proton pump inhibitors) and H2 receptor blockers are covered under D.4: pH regulation of the stomach in option D: Medicinal chemistry. The long term and short term side-effects of drugs are also covered under Option D.

Long term use of PPIs, such as omeprazole and esomeprazole, has been shown to lead to an increase in death due to an increase in cardiovascular disease, chronic kidney disease, and upper gastrointestinal cancer. Today (29 September 2019) several news agencies, e.g. Reuters, The BBC and ABC news have just announced that one of the big US retailers of drugs and medicines has suspended the sale of Zantac, the most popular H2 receptor blocker, as it may be linked to a cancer risk. This follows several other suppliers of Zantac in the US such as Walgreens, Walmart and Rite Aid. The active ingredient in Zantac is ranitidine but it is the presence of NDMA in ranitidine-containing products which is the cause of concern.

The structure of N-nitrosodimethylamine (NDMA)

NDMA is N-nitrosodimethylamine and although found in very small quantities of some foodstuffs, such as meat and dairy products, it is a known carcinogen. Many countries around the world are now suspending the sale of any ranitidine-containing products (and in some cases actually recalling products already sold) until the dangers of the NDMA content have been properly evaluated.