Clozapine's antipsychotic action is likely mediated through a combination of antogistic effects at D2 receptors in the mesolimbic pathway and 5-HT2A receptors in the frontal cortex. D2 antagonism relieves positive symptoms while 5-HT2A antagonism alleviates negative symptoms.
Clozapine is a psychotropic agent belonging to the chemical class of benzisoxazole derivatives and is indicated for the treatment of schizophrenia. Clozapine is a selective monoaminergic antagonist with high affinity for the serotonin Type 2 (5HT2), dopamine Type 2 (D2), 1 and 2 adrenergic, and H1 histaminergic receptors. Clozapine acts as an antagonist at other receptors, but with lower potency. Antagonism at receptors other than dopamine and 5HT2 with similar receptor affinities may explain some of the other therapeutic and side effects of Clozapine. Clozapine's antagonism of muscarinic M1-5 receptors may explain its anticholinergic effects. Clozapine's antagonism of histamine H1 receptors may explain the somnolence observed with this drug. Clozapine's antagonism of adrenergic a1 receptors may explain the orthostatic hypotension observed with this drug.
Clozapine carries a black-box warning for agranulocytosis.
Alvir JM, Lieberman JA, Safferman AZ, Schwimmer JL, Schaaf JA: Clozapine-induced agranulocytosis. Incidence and risk factors in the United States. N Engl J Med. 1993 Jul 15;329(3):162-7. [PubMed:8515788]
Vaddadi KS, Soosai E, Vaddadi G: Low blood selenium concentrations in schizophrenic patients on clozapine. Br J Clin Pharmacol. 2003 Mar;55(3):307-9. [PubMed:12630982]
Naheed M, Green B: Focus on clozapine. Curr Med Res Opin. 2001;17(3):223-9. [PubMed:11900316]
Lane HY, Chang YC, Chang WH, Lin SK, Tseng YT, Jann MW: Effects of gender and age on plasma levels of clozapine and its metabolites: analyzed by critical statistics. J Clin Psychiatry. 1999 Jan;60(1):36-40. [PubMed:10074876]