Clozapine and D1/D2 antagonism in extrapyramidal functions.

One of the main advantages of clozapine is that it rarely produces extrapyramidal syndromes and tardive dyskinesia. This advantage is linked to the atypical biochemical profile of clozapine, especially its combined and low blockade of D1 and D2 receptors. The level of D2 receptor blockade is too low to induce extrapyramidal side-effects, and D1 antagonists have a lower extrapyramidal side-effect potential than traditional D2 neuroleptics, especially with respect to dystonia. The combined and balanced D1/D2 receptor blockade may prevent the development of a dysbalance between D1/D2 receptor function (in favour of D1) which otherwise might lead to tardive dyskinesia.