Indicated to treat irritable, non-productive cough, clobutinol hydrochloride, marketed as Silomat, was believed to be well-tolerated since its introduction in 1961, but scientific evidence in literature research suggested otherwise, leading the German pharmaceutical company to undergo its own study.
A preclinical test followed by a clinical study in healthy volunteers suggested that a potential risk of cardiac arrhythmia could not be excluded.
In a statement released on Friday, the company said: "This potential risk might be very low, but considering the indication and the availability of therapeutic alternatives, Boehringer Ingelheim has decided in the interest of patients' safety to withdraw its clobutinol-containing products from the market as a precautionary measure."
Fifty-nine countries will be affected by the recall with an estimated seven to 10 million packs being withdrawn worldwide.
Speaking to in-PharmaTechnologist.com, Boehringer Ingelheim spokeswoman Judith von Gordon said the study findings came as a surprise to the company.
"We haven't had any [cardiac arrhythmia] cases reported . . .
There is nothing in the files, but the risk cannot be excluded," she said.
The drug has been on the market for 46 years with about 200 million people having used the drug.
"This is a decision we have made to exclude the risks from patients that used to take clobutinol.
We reacted quite quickly [after receiving the study results a week prior].
We really tried to react as quickly as possible.
"We think the findings are substance related and nothing to do with the formulation," she said.
Despite Silomat posting €26m in worldwide sales last year, von Gordon said the drug only made up 0.2 per cent of worldwide business sales for the company, meaning the impact of the recall would be limited.
There would be no manufacturing cutbacks, job losses or changes to other manufacturing aspects in regards to the recall, von Gordon said.
The company was not considering reformulating the product, which is an over-the-counter medication in some countries, and prescription-only in others.
Clobutinol, an antitussive, came off patent in the early 1980s and there are several generic products on the market, the producers of which will also be affected by these study findings, von Gordon said.
Ratiopharm is believed to have announced it would withdraw its products containing the active ingredient.
Novartis also uses clobutinol in its products Hexal and Stada.
The company was unavailable for comment.
Boehringer Ingelheim also manufacturers cough and cold expectorants Mucosolvan (ambroxol) and Bisolvon (b romhexine).