Pharmacodynamics +<unk>  Site Ki (nM) Species Ref >10,000 Human >10,000 Human >10,000 Human 5-HT2A >10,000 Human 5-HT2C >10,000 Human α1B >10,000 Human α2A >10,000 Human α2B >10,000 Human α2C >10,000 Human H1 42 Human H2 H3 >10,000 Human H4 M1 490 Human M2 2,100 Human M3 650 Human M4 380 Human M5 180 Human Values are Ki (nM), unless otherwise noted. The smaller the value, the more strongly the drug binds to the site.<unk>  acts primarily as an antagonist or inverse agonist of the histamine H1 receptor. This action is responsible for its antihistamine and sedative properties. To a lesser extent,<unk>  acts as an antagonist of the muscarinic acetylcholine receptors, an action responsible for its anticholinergic and (at high doses) deliriant effects. Pharmacokinetics The bioavailability of<unk>  is 24.7% for oral administration and 70.8% for intranasal administration. The Tmax of<unk>  is 1.5 to 2.5 hours. Its elimination half-life is 10 to 12 hours (range 7 to 13 hours).<unk>  is metabolized in the liver primarily by the cytochrome P450 enzymes CYP2D6, CYP1A2, and CYP2C9. The main metabolites are N-desmethyldoxylamine, N,N-didesmethyldoxylamine, and<unk>  N-oxide.<unk>  is eliminated 60% in the urine and 40% in feces.<unk>  concentrations after a single 25 mg oral dose of<unk>  in healthy volunteers. X-axis represents the time in hours after initial dose.
Doxylamine
Levopropylhexedrine
Difelikefalin
Halofantrine
Pentomone
Diallyllysergamide
Levomepromazine
Ethylnorepinephrine