indication

For symptomatic relief of seasonal and perennial allergic rhinitis and vasomotor rhinitis, as well as allergic conjunctivitis caused by foods and inhaled allergens. Also for the relief of allergic reactions to blood or plasma, and the symptomatic management of mild, uncomplicated allergic skin manifestations of urticaria and angioedema.

pharmacology

Carbinoxamine is a first generation antihistamine of the ethanolamine class. Ethanolamine antihistamines have significant antimuscarinic activity and produce marked sedation in most patients. In addition to the usual allergic symptoms, the drug also treats irritant cough and nausea, vomiting, and vertigo associated with motion sickness. It also is used commonly to treat drug-induced extrapyramidal symptoms as well as to treat mild cases of Parkinson's disease. Rather than preventing the release of histamine, as do cromolyn and nedocromil, carbinoxamine competes with free histamine for binding at HA-receptor sites. Carbinoxamine competitively antagonizes the effects of histamine on HA-receptors in the GI tract, uterus, large blood vessels, and bronchial muscle. Ethanolamine derivatives have greater anticholinergic activity than do other antihistamines, which probably accounts for the antidyskinetic action of carbinoxamine.

mechanism of action

Carbinoxamine competes with free histamine for binding at HA-receptor sites. This antagonizes the effects of histamine on HA-receptors, leading to a reduction of the negative symptoms brought on by histamine HA-receptor binding. Carbinoxamine's anticholinergic action appears to be due to a central antimuscarinic effect, which also may be responsible for its antiemetic effects, although the exact mechanism is unknown.

half life

10 to 20 hours

drug interactions

Benzylpenicilloyl Polylysine: Antihistamines may diminish the diagnostic effect of Benzylpenicilloyl Polylysine. Treatment with systemic histamine H1 antagonists such as carbinoxamine should be suspended for benzylpenicilloyl-polylysine skin testing to minimize the potential for false negative results. Delay skin testing until the systemic effects of the antihistamine have dissipated. A histamine skin test may be used to assess residual antihistaminic effects.

Donepezil: Possible antagonism of action

Galantamine: Possible antagonism of action

Pramlintide: Pramlintide may enhance the anticholinergic effect of Anticholinergics such as carbinoxamine. These effects are specific to the gastrointestinal tract. Use caution during concomitant therapy with pramlintide and anticholinergics. Additive effects on reduced gastrointestinal motility may occur.

Tacrine: The therapeutic effects of the central acetylcholinesterase inhibitor, Tacrine, and/or the anticholinergic, Carbinoxamine, may be reduced due to antagonism. The interaction may be beneficial when the anticholinergic action is a side effect. Monitor for decreased efficacy of both agents.

Trimethobenzamide: Trimethobenzamide and Carbinoxamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Triprolidine: Triprolidine and Carbinoxamine, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Additive CNS depressant effects may also occur. Monitor for enhanced anticholinergic and CNS depressant effects.

Trospium: Trospium and Carbinoxamine, two anticholinergics, may cause additive anticholinergic effects and enhanced adverse/toxic effects. Monitor for enhanced anticholinergic effects.