Management of schizophrenia; patients who fail to respond to or experience severe extrapyramidal side effects w/ classical antipsychotics. Reducing the risk of recurrent suicidal behavior in patients w/ schizophrenia. Management of treatment-resistant psychoses associated w/ Parkinson's disease.
Schizophrenia including reducing the risk of suicidal behavior Usual dose: 12.5 mg (half 25 mg tab) once daily or bid on the first day followed by 25 mg bid on the second day. Therapeutic dose: 200-400 mg daily in divided doses. Max: 900 mg/day. Maintenance: 200 mg or less as a single dose. Psychoses in Parkinson's disease Initially, <12.5 mg once daily, may increase to 12.5 mg w/ up to 2 increases each wk. Therapeutic dose: 25-37.5 mg. Increases above 50 mg should be made at wkly intervals. Max: 100 mg/day. Maintenance: may increase in wkly increments of 12.5-100 mg/day as a single dose or in 2 divided doses. Ending therapy: decrements of 12.5 mg over 1-2 wk.
Uncontrolled epilepsy, alcoholic or toxic psychoses, drug intoxication or history of circulatory collapse; patients w/ bone-marrow suppression, myeloproliferative disorders, abnormalities of WBC or differential count; history of drug-induced neutropenia or agranulocytosis; history of cardiac impairment. Cardiac failure, paralytic ileus. Severe renal & hepatic impairment, liver disease.
Agranulocytosis. Baseline total & differential WBC count is required before initiation, during & after termination of treatment. Total counts should be monitored every wk for 4 mth & thereafter every fortnight till 4 wk after discontinuing therapy. Monitor for hyperglycemia especially in patients w/ or at risk of developing diabetes. Monitor BP for the 1st 2 wk of treatment. Avoid abrupt w/drawal. May affect ability to drive or operate machinery. Pregnancy & lactation.
May enhance central effects of CNS depressants including alcohol, benzodiazepines, MAOIs. Reduce effects of α-adrenoreceptors agonists eg, noradrenaline. Additive effects w/ anticholinergic, hypotensive, resp depressant drugs. Increased plasma conc w/ drugs that inhibit or act as a substrate to CYPP450 & patients who suddenly stop smoking. May accelerate metabolism & reduce plasma conc w/ phenytoin or other enzyme-inducing drugs. Drugs w/c carry a high risk of bone-marrow suppression including carbamazepine, cotrimoxazole, chloramphenicol, penicillamine, sulfonamides, antineoplastics or pyrazolone analgesics eg, azapropazone; long acting antipsychotics.
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