Acute ketotifen overdosage. A review of present clinical experience.

Ketotifen (Zaditen) is a widely used prophylactic antiasthmatic drug with pronounced antianaphylactic properties and a specific H1-antihistaminic effect. This article summarises the available information on acute overdosage of this drug, which was reported in 13 adults and 8 children. The symptoms of acute overdosage observed with ketotifen are similar to those described for antihistaminic agents. However, it would appear that the acute toxicity of ketotifen is rather low, since no serious effects have been reported either in children or in adults after the intake of up to 20mg of ketotifen, which is 10 times the recommended dose. No lethal outcome of acute overdosage has been described in association with this drug. Ketotifen seems to be better tolerated in children than in adults. Based on present clinical experience, management of acute overdosage includes gastric lavage within 2 to 4h after ingestion or activated charcoal after this period. Symptomatic treatment is indicated if arrhythmias, hypotension or seizures develop, and the patient should be kept under surveillance for at least 6 to 8h.