Risks of non-prescription medication as shown by clobutinol as an example

INTRODUCTION. The arbitrary use of additional drugs other than prescribed medication is known to be a huge part of drug sales. However, the interactions of such non-prescription medication with any daily medication or concomitant diseases remain often unclear. Recently, in accordance with the decision of the competent authority in Germany, clobutinol (e.g. Silomat®), a drug against non-productive cough was withdrawn in all countries worldwide in which this medication had been available. The drug had first been approved in 1961 and estimated to have had 200 million patient exposures. A recent clinical study revealed that clobutinol can prolong the QT interval compared to placebo and may thus cause cardiac tachyarrhythmias. Even in therapeutic doses (240 mg daily) this effect was seen in healthy volunteers. Furthermore, this study was prematurely discountinued because of an epileptic grand mal seizure in one volunteer, suggesting neurological side effects of clobutinol. DISCUSSION. Clobutinol prolongs the QT interval and may cause life-threatening arrhythmias. This should serve as a warning to doctors to be careful when prescribing non-prescription medication. CONCLUSION. Non-prescription drugs can be a potential risk for patients who are also taking other pharmaceutical preparations or having concomitant disease. This is because such drugs may cause harmful interactions, most of them previously unknown. All doctors should avoid unsupervised use of non-prescription medication.