atropine

atropine (at-ro-peen)
Atro-Pen
Classification
Therapeutic: antiarrhythmics
Pharmacologic: anticholinergics, antimuscarinics
Pregnancy Category C
See Appendix C for ophthalmic use

Indications
IM: Given preoperatively to decrease oral and respiratory secretions. IV: Treatment of sinus
bradycardia and heart block.
PO: Adjunctive therapy in the management of peptic ulcer and irritable
bowel syndrome.
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 oral, 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)

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; A 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, PO(Adults): 0.4–0.6 mg 30– 60 min pre-op.
IM, IV, Subcut, PO (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, PO (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)
Tablets: 0.4 mg. In combination with: phenobarbital oral solution (Antrocol).
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.

NURSING IMPLICATIONS
Assessment
● Assess vital signs and ECG tracings frequently during IV drug therapy. Report any significant changes in heart rate or blood pressure, or increased ventricular ectopy or angina to physician promptly.
● Monitor intake and output ratios in elderly or surgical patients because atropine may cause urinary retention.
● Assess patients routinely for abdominal distention and auscultate for bowel sounds. If constipation becomes a problem, increasing fluids and adding bulk to the diet may help alleviate constipation.
● Toxicity and Overdose: If overdose occurs, physostigmine is the antidote.
● Geri: Inform male patients with benign prostatic hyperplasia that atropine may cause urinary hesitancy and retention. Changes in urinary stream should be reported to health care professional.

Evaluation/Desired Outcomes
● Increase in heart rate.
● Dryness of mouth.
● Reversal of muscarinic effects.

Posted in: ANTICHOLINERGICS