Levodopa dosage

Patients currently treated with levodopa Levodopa must be discontinued at least 12 hours before therapy with levodopa/carbidopa. Substitute the combination drug at a dosage that will provide about 25% of the previous levodopa dosage. 

Maintenance treatment - Pramipexole is effective and well tolerated over a dosage range of 1.5 to 4.5 mg/day administered in equally divided doses 3 times/day with or without concomitant levodopa ( 800 mg/day). When pramipexole is used in combination with levodopa, consider a reduction of the levodopa dosage. 

Plan to reduce the levodopa dosage if the patient experiences hallucinations. Keep in mind that hallucinations are usually accompanied by confusion and, to a lesser extent, insomnia... 

The primary problem associated with COMT inhibitors is an initial increase in dyskinesias.10 This problem may be due to the fact that the COMT inhibitor is allowing more levodopa to reach the brain, and that the levodopa dosage needs to be lowered accordingly. Other side effects include nausea, diarrhea, dizziness, and muscle pain/cramps. 

The long-term consequences of levodopa therapy have been considered in a review by predominantly Canadian authors, but whose senior author was Oleh Homykiewicz, the doyen of the dopamine concept of Parkinson s disease (16). Their conclusions were not at aU unexpected. Levodopa was given to 42 patients (30 men, mean disease duration of 16 years, mean follow-up about 9 years). There were adverse effects in over 70% dyskinesias in 62%, on-off effects in about 17%, and end-of-dose wearing-off in about 7% (the last perhaps surprisingly low). Dyskinesia was not only the most common but also the earliest adverse effect. It should be noted that the mean levodopa dosage in this population was rather low, only 500 mg/day. 

Start hesitation (paradoxical akinesia) is the name given to sudden episodes during which the patient feels a sensation of extreme heaviness of the feet and finds himself unable to start walking the legs tremble and the patient falls forward the condition can improve if the levodopa dosage is reduced. 

Neurologists from Madrid have studied 168 consecutive patients treated for at least 6 months with levodopa (57). About 10% of the patients per year developed dyskinesias over 7 years. Younger age (under 50 years) at the onset of the disease and high initial levodopa dosages (more than 600 mg/day) were the most important susceptibility factors identified. 

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. 

If hallucinations occur, they may be eliminated if levodopa dosage is reduced. Hallucinations generally are accompanied by confusion and to a lesser extend insomnia. 

Other reports in patients taking levodopa alone describe reductions in the levodopa dosage of up to 30% and 70% during concurrent treatment with methyldopa. Another report states that the control of Parkinson s disease improved during the concurrent use of methyldopa in some patients taking levodopa alone, hut the dyskinesias were worsened in others. Methyldopa on its own can cause a reversihle parkinsonian-like syn-drome. " ... 

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