The US Food & Drug Administration on Friday ordered Novartis, the pharmaceutical company, to withdraw its best-selling irritable bowel syndrome drug Zelnorm from the market after identifying cardiac side-effects.

The regulator’s move will freeze almost all sales of the medicine, Novartis’ 12th-highest seller, which generated revenue of $561m worldwide last year including $488m in the US.

Novartis reduced its financial forecasts on the back of the announcement, saying net sales growth in local currency were “above 5 per cent” in place of “mid to high single-digit” reported in January. It cut projected growth in the pharmaceutical division to “low to mid-single-digit” growth from “mid-single-digit.”

The move marks a blow for Novartis, which heavily marketed Zelnorm in the US linked to the condition of irritable bowel syndrome with constipation, which it says affects 12m Americans.

It also highlights intensifying interest by regulators in the scrutiny of safety data after the launch of drugs, notably spurred by concerns after the withdrawal of Vioxx, a painkiller, in 2004.

James Shannon, global head of development at Novartis Pharma, said: “Although we have complied with the FDA’s request and are collaborating with the agency, we continue to believe that Zelnorm/Zelmac provides important benefits for appropriate patients.”

The regulator’s decision came after Novartis informed the FDA of the results of an analysis of 18,000 patients in different clinical trials using the drug revealed a statistically higher incidence of angina pectoris, or constriction of blood to the heart, than those on placebo.

Thirteen patients using Zelnorm reported problems compared with one on placebo, although all had a history of cardiovascular disease or risk factors, the company said.

The fresh analysis contrasted with a study that had identified a non-statistically significant incidence of angina pectoris, and was included on the label provided with the drug at the time of its original approval in July 2002.

Novartis cited Jeffrey Anderson, a professor of internal medicine at the University of Utah, who reviewed the data, as saying: “My review of the data suggested that a causal relationship is unlikely between [Zelnorm] and the rare cardiovascular ischemic events observed in clinical trials.”

Copyright The Financial Times Limited 2018. All rights reserved.

Comments have not been enabled for this article.