“Serious” and “severe” adverse drug reactions need defining

Editor—In her editorial on the new guidelines for preventing malaria in UK travellers Zuckerman claims that a recent double blinded study showed high tolerability to the four recommended drug regimens, with no serious adverse events.¹,² Unfortunately, neither Zuckerman nor the cited study defines the term “serious.”

Therefore readers can assume only that, in accordance with the definition of the Council for International Organisations of Medical Sciences, we are probably talking about adverse drug reactions that are fatal, life threatening, leading to or prolonging a stay in hospital, or resulting in severe disability.³

This restrictive definition unfortunately ignores less serious but nevertheless highly disturbing and often severe problems encountered by travellers taking prophylactic malaria drugs. Two large, double blinded studies have proved that mefloquine commonly causes moderate to severe (neuropsychiatric) adverse events in travellers.²,⁴

In addition to this, less common serious adverse reactions remain a concern, as Zuckerman points out. Since August 2003 the US version of mefloquine (Lariam) has been delivered with a guide warning of adverse neuropsychiatric events and rare reports of suicide.⁵ No such guide is currently available to customers in other countries, leaving travellers no other choice than being informed by their doctors, pharmacists, or the international media. In view of the better tolerance of other (equally effective) drugs, the time has come for the Health Protection Agency advisory committee on malaria prevention for UK travellers to reconsider its use of mefloquine as a first line drug for the prevention of malaria.