Interactions between zyprexa(olanzapine) and Clozapine synthon (clozapine)
clozapine and olanzapine (Major Drug-Drug)
MONITOR CLOSELY: Coadministration with other psychotropic agents may potentiate the adverse effects of clozapine on cardiovascular function. Orthostatic hypotension with or without syncope, in rare cases accompanied by profound collapse and respiratory and/or cardiac arrest, has occurred during initiation of clozapine treatment alone and in patients receiving other psychotropic agents. The risk is greatest during initial titration in association with rapid dose escalation and may even occur on the first dose. In one report, initial doses as low as 12.5 mg were associated with collapse and respiratory arrest. Other adverse effects that may be increased during use of clozapine with other psychotropic agents include CNS depression, tardive dyskinesia, tachycardia, and ECG changes. Anticholinergic effects of these agents may also be additively increased. Excessive anticholinergic effects may result in paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of anticholinergic intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy and seizures.
MANAGEMENT: Caution is advised when clozapine is initiated in patients receiving other psychotropic drugs. Vital signs should be closely monitored. Patients who have had even a brief interval off clozapine (i.e. 2 or more days since the last dose) should be restarted with 12.5 mg once or twice daily. Particular caution is recommended in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication (e.g., abdominal pain, fever, heat intolerance, blurred vision, confusion, hallucinations) or cardiovascular toxicity (e.g., dizziness, palpitations, arrhythmias, syncope). Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A dosage reduction in one or both drugs may be necessary if excessive adverse effects develop.
