Core pharmacology

Class Group

Antimuscarinic

Legacy Cicm Level

Level 2

Indications Uses

- Protect against antimuscaranic effects when Acetylcholinesterase inhibitor used
- Treatment of bradycardia
- Hyperhydrosis
- Symptom control in palliative care

Chemical Pharmaceutics

Quaternary amine derivative of atropine

Presentation

Clear solution for injection or in combination with neostigmine

Mechanism of action

competitive antagonism at peripheral muscarinic receptors. More potent antagonism than atropine. Minimal anti-nicotinic effects, but more than atropine

Physiological effects

CVS: Tachycardia. Little effect on BP. Less arrhythmias than atropine. Vagolytic effects last 2-3 hours.

CNS: Does not cross BBB. No effect on pupils.

Resp: Bronchodilator. May increase dead space. Decreased bronchial secretions.

Renal: Difficulty micturition

GIT: Decreased salivation (8 hours). Decreased LOS.

Other: Inhibition of sweating but generally no effect on body temperature.

Adverse Effects Toxicity

- Tachycardia
- Dry mouth
- Urinary retention
- Inhibition of sweating

Absorption

poor oral absorption F 5%

Distribution

Rapid redistribution (90% disappears from plasma at 5 min)
- Crosses placenta
- Does not cross BBB

Volume of distribution

Vd 0.2-0.6L/Kg

Metabolism

Limited

Excretion

85% urine, 15% bile (80% unchanged)

Half-life

T1/2 of 1 hour