Atropine
Atropine sulfate
Also known as: Atrocare · Minims Atropine · Atropinum · Atropine sulphate · Atropine sulfate · Atropina
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (1)
Evidence only — not for automatic calculation
Premedication and treatment of vagally-mediated bradycardia
Premedication and treatment of vagally-mediated bradycardia: 0.04 – 0.05 mg/kg IV, SC, or IM 29 or intratracheally for CPR
Governing clinical context (2)
- NOTE: FDA approval has not been required for atropine products in animals. All dosages should be considered extra-label.
- Atropine sulfate for injection should be stored at room temperature between 15°C and 30°C (59°F-86°F).
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Atropine is a classic anticholinergic agent used primarily in veterinary medicine to treat bradycardia, dilate pupils for ophthalmic examinations, and manage specific toxicities (such as organophosphate and carbamate poisoning). It is also used in conjunction with anticholinesterase drugs during the antagonism of neuromuscular blockade.
Clinical Warning: Routine administration prior to anaesthesia as part of premedication is no longer recommended. It is better to monitor heart rate and administer atropine specifically to manage a low heart rate if necessary.
Mechanism of action
Atropine competitively blocks the action of acetylcholine at muscarinic receptors located at the terminal ends of the parasympathetic nervous system.
This blockade → reverses parasympathetic effects → produces mydriasis (pupil dilation), tachycardia, bronchodilation, and general inhibition of gastrointestinal function.
Safety & warnings
Contraindications
- Glaucoma
- Lens luxation
- Keratoconjunctivitis sicca (KCS / dry eye)
Adverse effects
- Sinus tachycardia
- Blurred vision (due to mydriasis)
- Drying of bronchial secretions
- Increased intraocular pressure (IOP)
- Reduced tear production
- Ventricular arrhythmias
- Hypersalivation (especially in cats, due to bitter taste of ophthalmic drops)
- Ileus (rare in small animals)
- Vomiting (rare in small animals)
Precautions
Atropine has a slow onset of action (10 min IM, 2-3 min IV); therefore, it is important to wait for an adequate period of time for the desired effect before redosing.
Clinical Pearl: The ophthalmic solution tastes very bitter. If it drains through the nasolacrimal duct into the mouth, it can cause profound hypersalivation, particularly in cats and some dogs.
Blurred vision from mydriasis may worsen recovery from anaesthesia.
Drug interactions
Incompatible when mixed together
May enhance the activity of atropine
May enhance the activity of atropine
May enhance the activity of atropine
May enhance the activity of atropine
May enhance the activity of atropine
May enhance the activity of atropine
Combining is not recommended
May aggravate toxicity signs, leading to hypertension and gut stasis
Additive anticholinergic effects
May cause paradoxical hypertension and significantly increased myocardial workload; concurrent use is generally discouraged
Atropine antagonizes the prokinetic effects of metoclopramide on the GI tract
Monitoring
- Heart rate and rhythm (ECG)
- Pupillary light reflex and pupil size
- Intraocular pressure (IOP)
- Tear production (Schirmer Tear Test)
Pharmacokinetics
Absorption
Slow onset of action: 10 minutes via IM route, 2-3 minutes via IV route.
Overdose
Overdose may lead to severe sinus tachycardia, ventricular arrhythmias (which may be treated with lidocaine if severe), extreme mydriasis, severe drying of secretions, and gastrointestinal stasis.
Available products
Formulations
- Injectable: 0.6 mg/ml
- Ophthalmic: 1% solution in single-use vials, 10 ml bottle
Veterinary
- Atrocare Injectable 0.6 mg/ml
- Atropine Ophthalmic 1% solution
Regulatory status
Withdrawal times: cattle meat 14 days · cattle milk 3 days
Withdrawal times may vary by specific member state and product formulation.
POM-V (Prescription Only Medicine - Veterinarian).
No regulatory data for: 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
The solution should be protected from light. Ophthalmic single-use vials do not contain any antimicrobial preservative; therefore, any remaining solution in the vial should be discarded immediately after use.
Client information
Atropine is often used in emergency situations to stabilize your pet's heart rate or as eye drops to dilate the pupil for examination.
Note on Eye Drops: The ophthalmic solution has a very bitter taste. If the drops drain into the back of the throat, your cat or dog may drool excessively. This is a normal reaction to the taste and is not a sign of toxicity. Protect your pet's eyes from bright light while their pupils are dilated.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.