Anti-Muscatinic agents

Question 1

What is the general mechanism of Anti muscarinic agents?

Answer 1

Parkinson’s disease is due to loss of DA neurons and OVERACTIVATION of cholinergic neurotransmission (DA – ACh imbalance) interneurons in the striatum.

• Anti-muscarinic agents have their therapeutic effect in PD by blocking the central cholinergic receptors that help balance cholinergic transmission in the basal ganglia. The exact mechanism by which the anticholinergic agents are beneficial for symptoms of Parkinson disease is unknown.

Question 2

What is the MOA of Anti Muscarinic agents?

Answer 2

MOA: Muscarinic Receptors (M1)– localized to striatal
neurons
Mediate cholinergic tremor in PD patients
May cause presynaptic inhibition of DA release

Question 3

What are the Musciranic receptor antagonist?

Answer 3

Trihexyphenidyl

Benztropine mesylate

Question 4

What are the clinical uses of Trihexyphenidyl

Benztropine mesylate?

Answer 4

• Useful in patients on NEUROLEPTIC DRUGS - - - anti-dopaminergic properties antagonize the effects of levodopa.
  
  • Improve tremor in 50% PD patients, but they do not improve bradykinesia or muscle rigidity

Question 5

What are the savers effect of Trihexyphenidyl

Benztropine mesylate?

Answer 5

• Characterized as “atropine-like” = dry mouth, inability to sweat, impaired vision, urinary retention, constipation, drowsiness, confusion