The antihistamine and antiallergic effects are based on hydroxycin blocking the H1 histamine receptor and actively attenuating its activity. By affecting neurotransmitter systems in the brain, the drug also has sedative, tranquilizing, and antispasmodic effects. The effects of hydroxycin occur within 15 to 60 minutes and last up to 6 hours.
After oral administration, hydroxycin is rapidly absorbed from the gastrointestinal tract and reaches maximum plasma concentration after approximately 2 hours. The drug is metabolized in the liver by the CYP3A4 and CYP3A5 enzymes. 70% of the active intermediate hydroxyzine is excreted in the urine. The half-life in children, adults, and the elderly is approximately 7, 20, and 29 hours, respectively.
Hydroxycin should not be taken in case of:
- severe liver or kidney failure
- Prostate enlargement
- Narrow-angle glaucoma
- pregnancy and breastfeeding
Interactions with alcohol, central depressant drugs, MAO inhibitors, parasympathomimetics, and antihypertensives are possible with concomitant use, as well as with betahistine, epinephrine, phenytoin, and cimetidine.