Antihistamines and highway safety.

Area of Science:

• Pharmacology
• Traffic Safety
• Neuroscience

Background:

• Antihistamines are widely used, with two main classes: H1 and H2 antagonists.
• Some antihistamines, particularly older H1-antagonists, cause sedation and impair psychomotor skills.
• Histamine H2-antagonists have restricted medical use and varying safety profiles.

Purpose of the Study:

• To review evidence on antihistamine-induced psychomotor impairment as a traffic hazard.
• To assess the risks associated with H1 and H2 antihistamine subclasses.
• To evaluate the potential for drug interactions affecting central nervous system depressant effects.

Main Methods:

• Review of available scientific literature and evidence.
• Analysis of drug properties, receptor actions, and known side effects.
• Assessment of psychomotor performance data and drug interaction studies.

Main Results:

• Older H1-antagonists impair performance and interact with alcohol and CNS depressants.
• Newer H1-antagonists show less central nervous system penetration and impairment.
• Cimetidine (H2-antagonist) poses risks due to drug metabolism interference, unlike ranitidine.

Conclusions:

• Antihistamine use, especially older H1-types, may contribute to traffic accidents, though underreported.
• Newer H1-antagonists appear safer for driving.
• Careful prescribing of H2-antagonists like cimetidine is crucial to mitigate drug interaction risks.