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Indication & Dosage |
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| Oral |
| TREATMENT OF PARKINSONISM |
| Adult:
Initially, 125 mg bid; increase gradually every 3-7 days according to response. Max dose: 8 g daily in divided doses. |
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| Oral |
| TREATMENT OF PARKINSONISM IN CONJUNCTION WITH BENSERAZIDE |
| Adult:
Patients not previously on levodopa therapy: Initially, 50 mg 3 or 4 times daily; gradually increase in increments of 100 mg once or twice wkly. Increase initial dose to 100 mg tid for advanced disease stages. Maintenance dose: 400-800 mg daily in divided doses; most require <600 mg daily. Patients previously on levodopa monotherapy: 10-15% of the usual dose previously taken. Patient previously on other levodopa/dopa-decarboxylase combination therapy: Initially, 50 mg 3 or 4 times daily.
Elderly: Initially, 50 mg once or bid, then increase by 50 mg every 3rd or 4th day. |
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| Oral |
| TREATMENT OF PARKINSONISM IN CONJUNCTION WITH CARBIDOPA |
| Adult:
Patients not previously on levodopa therapy: Initially, 25 mg carbidopa with 100 mg levodopa tid; gradually increase in increments of 12.5 mg carbidopa with 50 mg levodopa or 25 mg carbidopa with 100 mg levodopa every day or on alternate days. Maintenance dose: 75-200 mg carbidopa with 750 mg to 2 g levodopa daily in divided doses. Max carbidopa dose: 200 mg daily. Patients previously on levodopa monotherapy: 20-25% of the dose previously taken 3 or 4 times daily. Patient previously on other levodopa/dopa-decarboxylase combination therapy: Initial dose should provide the same daily levodopa dose. |
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| Administration |
Should be taken with food. (GI discomfort may be reduced by increasing the dose of l-dopa gradually, &/or by taking w/ or after meals. However, taking l-dopa on a full stomach may lead to lower plasma conc. In later disease, it may be preferable to admin on an empty stomach if the patient can tolerate it. Keep a consistent diet. A change in diet to foods high in protein may delay l-dopa absorption & reduce amt taken up in circulation.) |
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| Precautions |
Heart disease, liver or renal disease, pulmonary disease, endocrine disorders, seizure disorders, dementia or psychosis; open-angle glaucoma, osteomalacia, history of peptic ulcer. Monitor hepatic, psychiatric, haematological, renal and CV functions periodically. May impair ability to drive or operate machinery. Elderly. Avoid abrupt withdrawal. Pregnancy and lactation. |
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Potentially Life-threatening
Adverse Drug Reactions |
Increased risk of hypertensive crises with nonselective MAOIs. Increased risk of cardiac arrhythmias with cyclopropane or halogenated anaesthetics. |
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| Adverse Drug Reactions |
GI disturbances e.g. nausea, vomiting, anorexia. GI bleeding in peptic ulcer patients. Orthostatic hypotension, cardiac arrhythmias. Psychiatric symptoms (especially the elderly), depression with or without suicidal tendency. Abnormal involuntary movements or dyskinesias, delirium, hallucinations. Slight elevation of liver enzymes, BUN and uric acid. Transient leucopenia and thrombocytopenia. |
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| Interactions |
ncreased postural hypotension and possible reduced absorption with TCAs. Reduced effects with phenothiazines, butyrophenones, thioxanthenes and other antipsychotic agents; reserpine, papaverine, phenytoin, isoniazid. Reversal of effects of levodopa monotherapy with pyridoxine. Exacerbation of abnormal involuntary movements and possibly delayed absorption with anticholinergics. Additive hypotensive effects with antihypertensive agents. Increased CNS toxicity with methyldopa. Exacerbation of parkinsonian symptoms with metoclopramide. |
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