Falso positivo a morfina en orina por reactividad cruzada con alimemazina

Abstract

Alimemazine (Variargil^®) is a non-specific reversible anti-H1 antihistamine that crosses the blood-brain barrier. It acts as anticholinergic drug. It is marketed in drop form (oral suspension). It is used to relieve seasonal allergic rhinitis, angioedema, mild urticaria, allergic conjunctivitis, and for difficulty in falling asleep in children. It has a very variable pharmacokinetic, excessive “heavy hangover drowsiness” and rebound effect after withdrawal. It is not authorised for children under 2 years of age. The case is presented of a patient seen in the emergency room due to drowsiness and lack of response to stimuli after administration of alimemazine due to difficulties in falling asleep.