US regulators have informed healthcare professionals that Boehringer Ingelheim’s chronic obstructive pulmonary disease blockbuster Spiriva may put patients at a higher risk of experiencing a stroke.

The move follows an analysis by the German drugmaker of safety data from 29 clinical studies testing either the Spiriva HandiHaler (tiotropium) or the European-Union approved version, Spiriva Respimat, in around 13,500 patients with COPD. From this pooled analysis, eight patients per 1,000 treated with Spiriva for one year were estimated to be at risk of stroke, compared to six per 1,000 in the placebo group.

But in its “early communication” with doctors, the US Food and Drug Administration stressed that these results should be interpreted “with caution”, and that it had not yet confirmed the results of the analysis. Furthermore, while such pooled analyses can provide early information on potential safety issues with medicines, their inherent limitations make it necessary to carry out additional assessment using other data sources, the agency explained.

Long-term data in June
Consequently, the FDA said it is working closely with Boehringer to investigate the potential link between Spiriva and stroke, including a review of post-marketing adverse events reported for the drug. In addition, a large four-year study of Spiriva called UPLIFT will provide additional safety information on the long-term use of the drug when data become available in June, after which regulators will be able to fully assess the risk.

In the meantime, the agency stressed that Spiriva HandiHaler is “an effective medicine” for controlling bronchospasm in patients with COPD and that patients should not cease treatment before consulting a doctor, but urged both patients and healthcare professionals to report any side effects immediately.