Glycopyrrolate
Glycopyrronium bromide
Also known as: Robinul-V · Robinul Forte · glycopyrronium bromide · AHR-504 · Acpan · AmTech · Gastrodyn · Glycostigmin
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 (extra-label)
Premedication (extra-label): 0.01 – 0.02 mg/kg IM, SC, or IV
Governing clinical context (1)
- Glycopyrrolate tablets should be stored in tight containers and both the injection and tablets should be stored at room temperature (15°C -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
Glycopyrrolate is a synthetic quaternary ammonium antimuscarinic agent used primarily as a preanesthetic anticholinergic, to treat bradyarrhythmias, and to reduce hypersialism (excessive salivation).
Unlike atropine, its quaternary structure prevents it from crossing the blood-brain barrier appreciably, resulting in fewer central nervous system (CNS) side effects. It also has a longer duration of action for controlling salivary secretions compared to atropine.
Clinical Pearl: Glycopyrrolate is often preferred over atropine for preanesthetic use when prolonged reduction of salivary and respiratory secretions is desired without the risk of CNS stimulation or depression.
Mechanism of action
Glycopyrrolate acts as a competitive antagonist of acetylcholine at postganglionic muscarinic receptors (M1, M2, M3).
Acetylcholine → Blocked at Muscarinic Receptors → Decreased parasympathetic tone.
This blockade leads to:
- Heart: Vagolytic effect → Increased heart rate (tachycardia).
- Secretions: Antisialagogue effect → Profound reduction in salivary, tracheobronchial, and pharyngeal secretions.
- GI/Urinary: Decreased smooth muscle motility and tone.
- Eye: Mydriasis (pupil dilation) and cycloplegia.
Safety & warnings
Contraindications
- Narrow angle glaucoma
- Tachycardias
- Gastrointestinal ileus
- Urinary obstruction
- Hypersensitivity to the drug
- Pregnancy (per some manufacturer labels)
Adverse effects
- Dry secretions (xerostomia)
- Initial bradycardia followed by tachycardia
- Decreased gastrointestinal motility (risk of ileus)
- Decreased urinary tract motility
- Mydriasis and cycloplegia
Precautions
Use with extreme caution in patients with known or suspected GI infections, as decreased GI motility can prolong retention of toxins or causative agents. Use with extreme caution in patients with autonomic neuropathy.
Use cautiously in patients with hepatic or renal disease, geriatric or pediatric patients, hyperthyroidism, hypertension, congestive heart failure (CHF), tachyarrhythmias, prostatic hypertrophy, or esophageal reflux. Can produce sinus tachycardia and predispose hypotensive patients to cardiac arrhythmias (including ventricular fibrillation).
Drug interactions
May enhance the activity or toxicity of glycopyrrolate.
May enhance anticholinergic activity or toxicity.
May enhance anticholinergic activity or toxicity.
May enhance anticholinergic activity or toxicity.
May enhance anticholinergic activity or toxicity.
May aggravate signs seen with amitraz toxicity, leading to hypertension and further inhibition of peristalsis.
May decrease PO absorption; give oral glycopyrrolate at least 1 hour prior to oral antacids.
May increase intraocular pressure when used concurrently.
May increase serum digoxin levels; use regular digoxin tablets or oral liquid.
Increased gastric pH may decrease GI absorption; administer 2 hours after ketoconazole.
Glycopyrrolate may antagonize the prokinetic actions of metoclopramide.
Monitoring
- Heart rate and rhythm
- Respiratory rate and effort
- Gastrointestinal motility (auscultation for bowel sounds)
- Salivary and respiratory secretions
Pharmacokinetics
Absorption
Not completely absorbed after oral administration. In dogs, IV onset of action is generally within 1 minute. After IM or SC administration, peak effects occur approximately 30-45 minutes post-injection.
Distribution
Completely ionized quaternary ammonium compound; poor lipid solubility. Does not readily penetrate into the CNS or eye. Crosses the placenta only marginally.
Metabolism
Only a small amount is metabolized.
Elimination
Eliminated rapidly from the serum after IV administration (virtually no drug remains 30 minutes to 3 hours after dosing). Majority is eliminated unchanged in the feces and urine.
Overdose
In dogs, the LD50 is reported to be 25 mg/kg IV. In cats, the LD50 after IM injection is 283 mg/kg. Because of its quaternary structure, minimal CNS effects would be expected after an overdose compared to atropine. Overdose may present with severe anticholinergic signs (extreme tachycardia, mydriasis, dry mucous membranes, ileus). Treatment is generally supportive.
Available products
Formulations
- Injection
- Tablets
Veterinary
- Glycopyrrolate for Injection: 0.2 mg/mL in 20 mL vials; Robinul-V (Pfizer), generic
Human-labeled
- Glycopyrrolate Tablets: 1 mg & 2 mg; Robinul & Robinul Forte (Horizon); generic
- Glycopyrrolate Injection: 0.2 mg/mL in 1 mL, 2 mL, 5 mL, & 20 mL vials; Robinul (Robins); generic
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored in tight containers. Both injection and tablets should be stored at room temperature (15-30°C). Stable under ordinary conditions of light and temperature. Most stable in solution at an acidic pH; undergoes ester hydrolysis at pH above 6.
Client information
- Parenteral administration is best performed by professional staff in a clinical setting where adequate cardiac monitoring is available.
- If your pet is receiving glycopyrrolate tablets at home, allow free access to water and encourage drinking, as dry mouth is a common side effect.
- Monitor for signs of constipation or difficulty urinating, and contact your veterinarian if these occur.
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.