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Availability

Veterinary product

Injectable for IV ; IM; or SQ use
0.5 mg/mL in 30mL vial
2mg /mL in 100mL vial

Human product

Injectable: several concentrations
Tablets: 0.4mg tabs

Pharmacology

Atropine, a belladonna alkaloid, is both a central and a peripheral muscarinic blocking agent. It inhibits acetylcholine or other cholinergic stimulants at postganglionic parasympathetic neuroeffector sites.

The pharmacologic effects of atropine are dose related. When given in small doses it inhibits salivary and bronchial secretions. Given in moderate doses atropine can dilate pupils and increase heart rate. At large doses atropine decreases GI motility, and inhibits gastric acid secretion.

Atropine is readily absorbed following oral administration, IM injection, inhalation, or when given via endotracheal administration. It is well distributed in the body crossing into the central nervous system, and across the placenta. It has also been found distributed in breast milk in small quantities.

Atropine is metabolized in the liver and excreted into urine with 30-50% being excreted unchanged.

Indications

In pet rats it is used for: treatment of overdose of cholinergic agents, and as an antidote for organophosphate insecticide poisoning.

Drug Interactions or Contraindications

Atropine activity may be increased by the following:

Antihistamines
Procainamide
Meperidine
Benzodiazepines
Phenothiazines

Atropine may increase the activity of thiazdie diuretics and sympathomimetics.

*In humans atropine is contraindicated where narrow-angle glaucoma is suspected.*

Adverse Reactions

CNS:  stimulation, lethargy, ataxia (staggering gait, uncoordinated movement), seizures, respiratory depression

CV:  bradycardia (low heart rate) at low doses, tachycardia (high heart rate) at higher doses, arrhythmias (irregular heart rate )

EENT:  increased intraocular pressure when used topically in the eye

GI:  dry mouth, thirst, constipation

GU:  urinary retention

Other:  anaphylaxis

Dosage Recommendations

10 mg/kg , SQ, every 20 minutes, in organophosphate overdose until muscarinic signs disappear. ^{1  26}

Considerations

• Keep in closed container at room temperature.
• This drug can cause urinary retention. Monitor the rat’s fluid intake and output.

Posted on June 28, 2007, 16:11, Last updated on May 31, 2010, 19:26 | Cardiovascular Drugs