Parkinson's Disease Medicines - Drugs For Parkinson's Disease
Levodopa is the drug of first preference in the treatment of Parkinson's disease. It is a precursor of dopamine, a neurochemical, which is deficient In the brain of patients of this disase. Levodopa travels easily to the brain and gets converted into dopamine. This drug provides 50% relief in more than half the patients.
There is significant improvement in muscle rigidity and akinesia but not necessarily in tremors.
Dosage: The average oral dose of levodopa is 4 g per day. It is usually started in a smaller dose of 250 mg twice daily, which is increased by 250 to 500 mg every week. It has been found that relief sets in 4 to 8 weeks when the daily dose has reached 2 to 2.5 g. These increases in the dose are continued till the maximum benefit is achieved or adverse effects appear. Once the adequate dose is found, it can be taken for several years without losing its value.
Adverse Effects: During prolonged treatment with levodopa, a distressing complication of ' on≠off phenomenon' may occur, in which a person who has been showing continued improvement by taking this drug, suddenly starts behaving as though no drug is being given to him. This period ranges from an hour to half a day. The adverse effects of levodopa are common and include nausea, vomiting, orthostatic hypotension (a fall in blood pressure on sudden standing from a lying-down position), choreoathetoid movements (lip smacking, grimacing, head turning or abnormal involuntary movements of the upper or lower limbs), and occasionally toxic delirium, confusion, depression, restlessness, agitation, and hallucinations.
It is thought that the appearance of choreoathetoid movements is an indication of the maximum does that can be tolerated by a patient, but when this happens, the chances of the occurrence of an 'on-off phenomenon' also increase. It is, therefore, quite important to keep the doses as low as possible to avoid the occurrence of the adverse effects of choreoathetoid movements.
The drug should not be taken on an empty stomach.
Patients who show a pronounced decrease in blood pressure on standing up from a lying≠ down position should be protected from the possibility of fainting. They should be made to wear tight long socks and occasionally given small amounts of ephedrine.
The does should be reduced as soon as there appearance of choreoathetoid movements.
These agents should be used cautiously in patients suffering from liver or kidney disease.
The dose should be reduced if psychological symptoms persist.
Vitamin B6 reverses the effects of levodopa. Avoid use of B complex preparations which invariably contain Vitamin B6.
Anti-psychotic drugs may make levodopa ineffective, if administered simultaneously.
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