Cough syrup Silomat has been voluntarily withdrawn in Singapore by pharmaceutical group Boehringer-Ingelheim following concerns that it could increase the risk of an irregular heartbeat.

New findings from a clinical study in healthy subjects conducted by the group and analysed in the last few days suggest a "very low" risk of cardiac arrhythmia. However, Boehringer-Ingelheim said it decided to withdraw its clobutinol hydrochloride-containing medications (Silomat) in view of patient safety and the ready availability of alternative treatments.

The Health Sciences Authority of Singapore has been informed of this decision and a letter of notification has been sent to healthcare professionals who prescribe or dispense Silomat, said Boehringer-Ingelheim. Silomat is available locally in pharmacies only.

The pharmaceutical group also assured the public that the effects of the medication only occur during the period of use so patients who have used clobutinol need not be concerned about potential late adverse effects.

Those who were prescribed or dispensed the cough syrup can get a full refund by returning, latest by 30 Nov, the full or partly used packs of Silomat to the place from which they were obtained.