atropine

 Indications

IM: Given preoperatively to decrease oral and respiratory

secretions. IV: Treatment of sinus bradycardia and

heart block. IV: Reversal of adverse muscarinic effects

of anticholinesterase agents (neostigmine, physostigmine,

or pyridostigmine). IM, IV: Treatment of anticholinesterase

(organophosphate pesticide) poisoning.

Inhaln: Treatment of exercise-induced bronchospasm.

Action

Inhibits the action of acetylcholine at postganglionic

sites located in: Smooth muscle, Secretory glands, CNS

(antimuscarinic activity). Low doses decrease: Sweating,

Salivation, Respiratory secretions. Intermediate

doses result in: Mydriasis (pupillary dilation), Cycloplegia

(loss of visual accommodation), Increased heart

rate. GI and GU tract motility are decreased at larger

doses. Therapeutic Effects: Increased heart rate.

Decreased GI and respiratory secretions. Reversal of

muscarinic effects. May have a spasmolytic action on

the biliary and genitourinary tracts.

Pharmacokinetics

Absorption: Well absorbed following subcut or IM

administration.

Distribution: Readily crosses the blood-brain barrier.

Crosses the placenta and enters breast milk.

Metabolism and Excretion: Mostly metabolized

by the liver; 30–50% excreted unchanged by the kidneys.

Half-life: Children 2 yr: 4–10 hr; Children 2 yr:

1.5–3.5 hr; Adults: 4–5 hr.

TIME/ACTION PROFILE (inhibition of

salivation)

ROUTE ONSET PEAK DURATION

IM, subcut rapid 15–50 min 4–6 hr

IV immediate 2–4 min 4–6 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Angle-closure

glaucoma; Acute hemorrhage; Tachycardia secondary

to cardiac insufficiency or thyrotoxicosis; Obstructive

disease of the GI tract.

Use Cautiously in: Intra-abdominal infections;

Prostatic hyperplasia; Chronic renal, hepatic, pulmonary,

or cardiac disease; OB, Lactation: Safety not established;

IV administration may produce fetal tachycardia;

Pedi: Infants with Down syndrome have

increased sensitivity to cardiac effects and mydriasis.

Children may have increased susceptibility to adverse

reactions. Exercise care when prescribing to children

with spastic paralysis or brain damage; Geri: Increased

susceptibility to adverse reactions.

Adverse Reactions/Side Effects

CNS: drowsiness, confusion, hyperpyrexia. EENT:

blurred vision, cycloplegia, photophobia, dry eyes, mydriasis.

CV: tachycardia, palpitations, arrhythmias. GI:

dry mouth, constipation, impaired GI motility. GU: urinary

hesitancy, retention, impotency. Resp: tachypnea, pulmonary edema. Misc: flushing, decreased

sweating.

Interactions

Drug-Drug:qanticholinergic effects with other anticholinergics,

including antihistamines, tricyclic

antidepressants, quinidine, and disopyramide.

Anticholinergics may alter the absorption of other

orally administered drugs by slowing motility of the

GI tract. Antacidspabsorption of anticholinergics.

MayqGI mucosal lesions in patients taking oral potassium

chloride tablets. May alter response to betablockers.

Route/Dosage

Preanesthesia (To Decrease Salivation/

Secretions)

IM, IV, Subcut (Adults): 0.4–0.6 mg 30–60 min

pre-op.

IM, IV, Subcut (Children 5 kg): 0.01–0.02 mg/

kg/dose 30–60 min preop to a maximum of 0.4 mg/

dose; minimum: 0.1 mg/dose.

IM, IV, Subcut (Children 5 kg): 0.02 mg/kg/dose

30–60 min preop then q 4–6 hr as needed.

Bradycardia

IV (Adults): 0.5–1 mg; may repeat as needed q 5 min,

not to exceed a total of 2 mg (q 3–5 min in Advanced

Cardiac Life Support guidelines) or 0.04 mg/kg (total

vagolytic dose).

IV (Children): 0.02 mg/kg (maximum single dose is

0.5 mg in children and 1 mg in adolescents); may repeat

q 5 min up to a total dose of 1 mg in children (2

mg in adolescents).

Endotracheal (Children): use the IV dose and dilute

before administration.

Reversal of Adverse Muscarinic Effects

of Anticholinesterases

IV (Adults): 0.6–12 mg for each 0.5–2.5 mg of neostigmine

methylsulfate or 10–20 mg of pyridostigmine

bromide concurrently with anticholinesterase.

Organophosphate Poisoning

IM (Adults): 2 mg initially, then 2 mg q 10 min as

needed up to 3 times total.

IV (Adults): 1–2 mg/dose q 10–20 min until atropinic

effects observed then q 1–4 hr for 24 hr; up to 50

mg in first 24 hr and 2 g over several days may be given

in severe intoxication.

IM (Children 10 yr 90 lbs): 2 mg.

IM (Children 4–10 yr 40–90 lbs): 1 mg.

IM (Children 6 mo–4 yr 15–40 lbs): 0.5 mg.

IV (Children): 0.02–0.05 mg/kg q 10–20 min until

atropinic effects observed then q 1–4 hr for 24 hr.

Bronchospasm

Inhaln (Adults): 0.025–0.05 mg/kg/dose q 4–6 hr

as needed; maximum 2.5 mg/dose.

Inhaln (Children): 0.03–0.05 mg/kg/dose 3–4

times/day; maximum 2.5 mg/dose.

Availability (generic available)

Injection: 0.05 mg/mL, 0.1 mg/mL, 0.4 mg/mL, 1 mg/

mL, 0.5 mg/0.7 mL Auto-injector, 1 mg/0.7 mL Auto-injector,

2 mg/0.7 mL Auto-injector.