Antiparkinsonism agents

Parkinsonism & antiparkinsonism agents.

1. Parkinsonism & Antiparkinsonism agents Prepared by Ms. Nisha S. Mhaske M.Pharm (Q.A.T) Lecturer, PRES’s COPD, Chincholi. Email : [email protected] Loknete Dr.Balasaheb Vikhe Patil ( Padmabhushan Awardee ) Pravara Rural Education Society’s College of Pharmacy (D.Pharm) Nashik.

2. Parkinsonism Parkinsonism is caused due to deficiency of dopamine and increased acetylcholine at synapse. It is a clinical condition characterized by symptoms such as:- Muscular rigidity Tremors (Shaking movements/ vibrations) Akinesia (Inability to move) Excessive salivation Seborrhoea Liver damage, mood changes may occur Bradykinesia (slowness of movement) Postural instability

3. Antiparkinsonism agents The drugs which are used in the treatment of parkinsonism are called antiparkinsonism agents. Classification Drugs that replace dopamine, e.g.Levodopa , Carbidopa Drugs that release dopamine, e.g.Amantidine Anticholinergics , e.g. Atropine, Benzatropine , Procyclidine , Biperiden . Antihistaminics , e.g.Diphenhydramine , Promethazine , Orphenadrine Phenothiazines , e.g. Ethopropazine Drugs that mimic the action of dopamine, e.g.Bromocryptine .

4. Levodopa Pharmacological actions Levodopa gives all manifestations of parkinsonism hence it is called universal antiparkinsonism agent. Levodopa is converted into dopamine in the brain as well as in peripheral tissues by the enzyme dopa decarboxylase. The levodopa improves the conditions such as seborrhoea and also improves the mood, memory and makes the patients more interested in their surrounding. Levodopa increases psychomotor in-coordination. The young patients are benefited more than older. Parkinsonism due to Iodine and manganese poisoning are also treated by levodopa. Preparation- Levodopa tablet IP Dose- 125 mg twice daily Trade names- Levopa, Avopa.

5. Why is levodopa always given in combination with carbidopa ? Levodopa is a precursor of dopamine Levodopa can cross the blood brain barrier but dopamine cannot cross the blood brain barrier. The enzyme dopa decarboxylase is also present in the blood plasma which converts absorbed L-dopa to dopamine. Thus larger dose of l-dopa is required to increase clinically effective level of dopamine in the brain, which results in toxicity. Carbidopa does not cross the blood brain barrier but it inhibits peripherally dopa decarboxylase. Carbidopa prevents the conversion of levodopa out of the CNS peripherally, Therefore, levodopa is always given in combination with carbidopa .