H1-receptor antagonists. Comparative tolerability and safety.
First-generation histamine H1-receptor antagonists, such as diphenhydramine, triprolidine, hydroxyzine or chlorpheniramine (chlorphenamine), frequently cause somnolence or other CNS adverse effects. Second-generation H1-antagonists, such as terfenadine, astemizole, loratadine and cetirizine, represent a true advance in therapeutics. In manufacturers' recommended doses, they have a more favourable benefit/risk ratio than their predecessors with regard to lack of CNS effects, and do not exacerbate the adverse CNS effects of alcohol or other CNS-active chemicals. Rarely, some of the newer H1-antagonists may cause cardiac dysrhythmias after overdose or under other specific conditions. The concept of a risk-free H1-antagonist is proving to be an oversimplification. An H1-antagonist absolutely free from adverse effects under all circumstances is not yet available for use. The magnitude of the beneficial effects of each H1-antagonist should be related to the magnitude of the unwanted effects, especially in the CNS and cardiovascular system, and a benefit-risk ratio or therapeutic index should be developed for each medication in this class.
Simons
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Department of Pediatrics and Child Health, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
D000014:Abnormalities, Drug-Induced; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D002490:Central Nervous System / Q000187:drug effects*; D004347:Drug Interactions; D004562:Electrocardiography / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000009:adverse effects* / Q000633:toxicity; D006801:Humans; D017891:Pharmacoepidemiology; D011597:Psychomotor Performance / Q000187:drug effects
D006634:Histamine H1 Antagonists; D000431:Ethanol