Dextromethorphan. An overview of safety issues

Dextromethorphan is a highly effective and widely used nonopioid antitussive drug. As it has been in use for more than 30 years, a large body of clinical experience has been used to formulate a safety profile. An anthology of adverse drug events has been analysed, drawn both from published case records and a data base recording dextromethorphan-related adverse events spontaneously reported by physicians or pharmacists. The resulting safety profile indicates that adverse drug reactions are infrequent and usually not severe. The predominant symptoms are usually dose related and include neurological, cardiovascular and gastrointestinal disturbances. Particular safety concerns arise when monoamine oxidase inhibiting (MAOI) drugs and dextromethorphan are coadministered. In addition to adverse drug reactions, the safety profile of dextromethorphan is affected by episodic and sporadic abuse. In fact, abuse appeared to be the most significant hazard identified by analysis of spontaneous adverse event reporting. No evidence could be found that the well documented pharmacokinetic polymorphism observed with dextromethorphan is correlated with any clinically significant safety risk if it is used for short term treatment. In summary, the safety profile of dextromethorphan is reassuring, particularly relating to overdose in adults and children.