All are true about Clozapine except:
Ans. (B) Blood level below 350 mg/ml should be maintained to avoid agranulocytosis(Ref: Drug Facts and Comparisons 2006/1205-1206; Goodman Gilman 12th/427,432)High plasma concentration of Clozapine increases the risk of seizures (not agranulocytosis). However, usual plasma concentration required in many persons is 300-600 ng/ml.Clozapine is an atypical antipsychotic drug that has high potency to block 5HT2 receptors as compared to D2 receptors. It has high potency to block D2 as compared to D1 receptors.It should not be used with Carbamazepine due to two reasons:Carbamazepine induces its metabolism and thus decreases the plasma concentration.Carbamazepine has bone marrow suppressant action and can add to agranulocytosis caused by Clozapine.Clozapine should be started at low doses (12.5 mg) and gradually dose should be increased. Baseline WBC counts should be measured and then weekly counts should be done atleast for first 6 months. When WBC count becomes less than 3000/mm3 or absolute neutrophil count becomes less than 1500/mm3, Clozapine should be discontinued. After discontinuation, weekly WBC counts should be less than 2000/mm3 or absolute neutrophil count below 1000/mm3 should not be started on Clozapine again.
More potently blocks D2 as compared to D1 receptors
Blood level below 350 ng/ml should be maintained to avoid agranulocytosis
Should not be used along with Carbamazepine
Should be discontinued if the WBC count is below 3,000/mm3 cells
C.N.S