- Mechanism of Action
- Clinical Uses & Dosing
- Overdose and Central Anticholinergic Syndrome
Atropine combines reversibly (competitve antagonism) with muscarinic cholinergic receptors and thus prevents access of the neurotransmitter acetylcholine to these sites. It is thus termed an anticholinergic.
IV Administration: onset of action is about 1 minute; duration of action 30-60 minutes.
Atropine, like scopolamine, is a lipid soluble tertiary amine, and thus easily crosses the blood-brain barrier, causing CNS effects of sedation and delerium, esp. in the elderly. (See Central Anticholinergic Syndrome)
- Determining the "Correct" Patient Weight to use for Drug Calculations
In Combination with Anticholinesterase Drugs:
- -to prevent parasympathomimetic effects that occur with edrophonium, neostigmine, and pyridostigmine.
- -typical dosing with neostigmine (Click on Link)
- -common to see tachycardia for 3-5 minutes when mixing atropine and neostigmine in same syringe
- -usually supplied as 400 mcg/ml
- -Reference: Miller, Anesthesiology, Apr. 1976
- Antisialagogue Effect
- -atropine is the least potent of the common anticholinergics for inhibiting salivation (see table above)
- -dose Adult: 0.4mg (400 mcg)
- Treatment of Reflex-Mediated Bradycardia
- -Atropine is the anticholinergic of choice for treating an intraoperative bradycardia, particularly that resulting from increased parasympathetic nervous system activity.
- -Dose is 15 to 70 ug/kg IV (70kg adult= 1-4 mg)
- -Increases the heart rate by blocking the effects of acetylcholine on the sinoatrial node -Equivalent doses of glycopyrrolate produce similar increases in heart rate, but the onset of effect is slower than after the administration of atropine (Bevan et al., 1992).
- -EKG effect is to shorten the P-R interval.
- -I have seen atropine "shorten" the PR interval so much that the rhytym is essentially a nodal tachycardia.
- Preoperative Medication
- -less frequently used now. Was given for sedation and antisialogogue effects.
- - Adults: 0.4 - 0.6 mg IM
- Mydriasis and Cycloplegia
- -topically can produce mydriasis and cycloplegia lasting 7-14 Days. Parenterally, doses to treat reflex-mediated bradycardia do not produce sufficient tissue levels to produce adverse effectgs in patients with glaucoma