Parkinsonism & antiparkinsonism agents.

1. PARKINSONISM &
ANTIPARKINSONISM
AGENTS
Prepared by
Ms. Nisha S. Mhaske
M.Pharm (Q.A.T)
Lecturer, PRES’s COPD, Chincholi.
Email : nisha.mhaske@pravara.in

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:-
i. Muscular rigidity
ii. Tremors (Shaking movements/ vibrations)
iii. Akinesia (Inability to move)
iv. Excessive salivation
v. Seborrhoea
vi. Liver damage, mood changes may occur
vii. Bradykinesia (slowness of movement)
viii. Postural instability

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

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

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