Benzatropine

Question 1

MOA?

Answer 1

Anticholinergic agent used to treat dystonia/dyskinesia secondary to antipsychotics (also is antihistaminergic)

Question 2

Clinical features?

Answer 2

Anticholinergic:
Delirium
Visual hallucinations
Mydriasis
Sinus tachy
Warm, flushed dry skin
Urinary retention
Ileus

Question 3

How long can toxic effects last?

Answer 3

Within 6 hours to Days

Question 4

Treatment?

Answer 4

Specific: physostigmine 0.5-1mg IV
(not widely available)
Supportive: Benzos/droperidol

Question 5

What are the side effects of the antidote to benzatropine?

Answer 5

Bronchospasm
Bradycardia: IV conduction block/AV block
Seizures

Question 6

What is the MOA of the antidote?

Answer 6

Acetylcholinesterase inhibitor
Reversible inhibition resulting in increased ACh which can then overcome the anticholinergic actionsoccurring

Question 7

What are contraindications to antidote use?

Answer 7

Pre-existing heart block/bradycardia
(can cause CHB/asystole!)

Question 8

Use of the antidote may reduce what?

Answer 8

Excessive benzo use and subsequent sedation

Question 9

How do you treat excessive antidote use?

Answer 9

Physostigmine is cholinergic so can be managed with IV doses of atropine

Question 10

If you have to intubate someone who you’ve used physostigmine on what is it important to consider in regard to muscle relaxants?

Answer 10

It prolongs the action of suxamethonium (need smaller dose)
It inhibits the action of non-depolarizing relaxants (need bigger dose)