[Adverse effects of oxybutynin chloride (Ditropan). Evaluation of the official survey of Regional Pharmacovigilance Centers]

Abstract

We analyzed the 200 reported cases of adverse reactions to Ditropan (209 side-effects) collated by the Centres Régionaux de Pharmacovigilance and Laboratoire Debat since the drug was first marketed. The frequency of such side-effects was of the order of 1 per 20,917 treatment months. Children were affected four times more frequently than adults. The manifestations resembled atropine overdose in 103 cases (52 children, 51 adults), and were mainly neurological (59%) and ocular (22%). Two cases of erythema multiform and 33 of miscellaneous allergic skin reactions occurred. The fact that atropine overdose was more frequent in children can be explained by the proportionately higher dosage. Dose adjustment based on pediatric pharmacokinetic studies appears to be essential. In children, the drug is prescribed most frequently (56%) for conditions outside the licensed indications, particularly nocturnal enuresis, a condition for which the efficacy of Ditropan has not been established. We consider that this calls for a specific contraindication in isolated nocturnal enuresis and in children aged less than five years.