Levodopa Clozapine

Allopurinol, aspirin, carbamazepine, chlorpropamide, clomipramine, clozapine, colchicine, desipramine, gold salts, imipramine, levodopa, penicillamine, phenothiazines, phenytoin, propylthiouracil, and sulfonylureas... 

A 73-year-old woman with a 4-year history of Parkinson s disease developed hallucinations and delusions that were interpreted as secondary effects of levodopa (187). She was given clozapine 25 mg/day and continued to take levodopa. Four days later she complained of abdominal pain. She had raised activities of serum amylase 806 IU/1 (reference range <220 IU/1), lipase 2598 IU/1 (<190 IU/1), and creatine kinase 464 IU/1 (<190 IU/1), and normal concentrations of total and direct bilirubin. Other causes of pancreatitis were ruled out. 

There is some evidence that the atypical neuroleptic drug clozapine can alleviate levodopa-induced dyskinesia while itself providing additional relief in Parkinson s disease (SEDA-18, 159) clozapine may also relieve levodopa-induced psychosis (SEDA-17,166). 

The efficacy of clozapine has been described in 60 patients with levodopa-induced neuropsychiatric syndromes (32 assigned to the active drug and 28 to placebo) (72). The mean age was 72 years, the mean duration of disease was 12 years (Hoehn and Yahr stage 3.2), and the mean levodopa dosage was 774 mg/day. At a dose of up to 50 mg/day, clozapine significantly improved psychotic features, with minimal effects on parkinsonian symptoms. Clozapine caused somnolence but was otherwise well tolerated. 

The manufacturer of APO-go specifically notes that there is a potential interaction between clozapine and apomorphine, although they say that clozapine may also be used to reduce the symptoms of neuropsychiatric complications of Parkinson s disease. See also prochlorperazine in (c) above, and Levodopa + Antipsychotics , p.683. 

Phenothiazines, butyrophenones, diphenylbutylpiperidines and thioxanthenes can oppose the effects of levodopa because of their dopamine antagonist properties, causing deterioration of motor function in Parkinson s disease. The antipsychotic effects and ex-trapyramidal adverse effects of these drugs can be opposed by levodopa. Of the atypical antipsychotics, risperidone and olanzapine cause deterioration in motor function in Parkinson s disease. Ziprasidone may act similarly, and there have been reports with quetiapine. Clozapine does not have this effect. 

Low-dose clozapine appears to cause little deterioration in motor function, and may improve tremor. It therefore remains the preferred antipsychotic for patients with Parkinson s disease and levodopa-induced psychosis. Note that individual reports and studies of the use of these antipsychotics in patients with Parkinson s disease are numerous. The reader is referred to a recent review on the topic. ... 

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