classical antihistamines meaning
- [Medicine]
Drugs that selectively bind to but do not activate histamine H1 receptors,thereby blocking the actions of endogenous histamine. Included here are the classical antihistaminics that antagonize or prevent the action of histamine mainly in immediate hypersensitivity. They act in the bronchi,capillaries,and some other smooth muscles,and are used to prevent or allay motion sickness,seasonal rhinitis,and allergic dermatitis and to induce somnolence. The effects of blocking central nervous system H1 receptors are not as well understood.
- Furthermore, the brain has a higher density of histamine H1 receptors than any body organ examined which may account for why chlorpromazine and other phenothiazine antipsychotics are as potent at these sites as the most potent classical antihistamines.
