Proconvulsant effect of ketotifen, a histamine H1 antagonist, confirmed by the use of d-chlorpheniramine with monitoring electroencephalography
Yokoyama, H.; Iinuma, K.; Yanai, K.; Watanabe, T.; Sakurai, E.; Onodera, K.
Methods and Findings in Experimental and Clinical Pharmacology 15(3): 183-188
1993
ISSN/ISBN: 0379-0355 PMID: 8101246 Document Number: 412042
Ketotifen produced seizures in a 5-year-old boy with secondary generalized epilepsy (SGE) and allergic rhinitis. To confirm that the seizures were due to histamine H-1 receptors blockade, d-chlorpheniramine was administered with monitoring electroencephalography (EEG). Administration of d-chlorpheniramine significantly increased the number of epileptic discharges in the patient, compared with those before administration. Plasma noradrenaline and dopamine levels were not affected by treatment with d-chlorpheniramine. These findings indicate that histamine H-1 receptors blockade produced convulsions and increased epileptic discharges on EEG. Recently, several experimental reports have shown that histamine has an inhibitory role on convulsions through histamine H-1 receptors. Experimental findings and present results show that histamine H-1 antagonists have proconvulsant effects, especially in the developmental period. Thus, it is recommended that centrally-acting histamine H-1 antagonists should be avoided in epileptic patients, especially in children of pre-school age.