LEVODOPA

It is inactive by itself, but is the immediate precursor of the transmitter. Dopamine Marked symptomatic improvement occurs in parkinsonian patients. Hypokinesia and rigidity resolve first, later tremor as well. Secondary symptoms of posture gait, handwriting, speech, facial epression, mood, selfcare and interest in life and gradually normalized. In some patients this progresses to excitment - frank psychosis & embarrasingly disproportionate increase in sexual activity.

Indications

Idiopathic, post-encephalitis & arteriosclerotic Parkinsonism.

Dosage

Start with 250 mg daily after meals increasing slowly by 250 mg increments over 3-4 days till max. therapeutic response is achieved (Max. 1-8 gm daily in divided does)

Contra-Indications

acute narrow angle glaucoma. Severe psychosis, history of malignant melanoma.

Special Precautions

Elderly, Ischaemic heart disease, cerebrovascular, psychiatric, endocrine, hepatic and renal disease, peptic ulcer. Paediatrics: Normally not prescribed. Pregnancy & Lactation: To be avoided. Elderly: No special problem.

Side Effects

Nausea, vomiting, postural hypoten- sion. Cardiac arrhythmias. Exacerbation of angina. Altertion in taste sensation. C.N.S. disturbances, involuntary movements, urine discolouration.

Drug Interactions

Hypertensive crises with furazolidone or MAOIs. Effects enhanced by the peripheral dopa decarboxylase inhibitors, amantadine, anticholinergics, amphetamine. Enhances hypotensive effects of bethanidine, bretylium, guanethidine. Phenothiazines, haloperidol, reserpine, diazepam, oxazepam, pyridoxine, chlordiazepoxide, phenobarbitone reduces effects of levodopa.