Table of Contents 17 sections Group Mechanism of Action Dose Rates Dogs Cats Horses Cattle Sheep Pigs Ruminant Indications Contraindications Interactions Adverse effects Toxicity Preparations Monitoring and Administration
Neostigmine Neostigmine is a peripheral acetylcholinesterase inhibitor.
Peripheral acetylcholinesterase inhibitor
Prolongs peripheral acetylcholine activity; penetration of the central nervous system is poor.
Dogs Use / stage Dose Route Schedule Instructions Oral antimyasthenic treatment Reference only PO Total 2 mg/kg/day orally in divided doses; the number and spacing of doses are not specified. Antimyasthenic treatment 10 mcg/kg IM, SC As needed Not intended for prolonged maintenance. Neuromuscular blockade reversal 40 mcg/kg IM, SC As needed Myasthenia diagnostic aid 40 mcg/kg IM Once Myasthenia diagnostic aid 20 mcg/kg IV Once Antimyasthenic treatment 0.04 mg/kg IM Every 6 h Alternative when regurgitation prevents oral dosing. Myasthenia diagnostic aid 0.05 mg/kg IM Once Pretreat with atropine; improvement is expected within 15-30 minutes if responsive. Neuromuscular blockade reversal 0.001 mg/kg SC Curare overdose report; followed by atropine 0.04 mg/kg IV.
Cats Use / stage Dose Route Schedule Instructions Oral antimyasthenic treatment Reference only PO Total 2 mg/kg/day orally in divided doses; the number and spacing of doses are not specified. Antimyasthenic treatment 10 mcg/kg IM, SC As needed Not intended for prolonged maintenance. Neuromuscular blockade reversal 40 mcg/kg IM, SC As needed Myasthenia diagnostic aid 40 mcg/kg IM Once Myasthenia diagnostic aid 20 mcg/kg IV Once Antimyasthenic treatment 0.04 mg/kg IM Every 6 h Alternative when regurgitation prevents oral dosing.
Horses Use / stage Dose Route Schedule Instructions Motility stimulation 0.02–0.04 mg/kg IV, SC Repeat according to response. Motility stimulation 0.008 mg/kg/hour IV Continuous Motility stimulation 0.0220462262 mg/kg SC As needed 1 mg per 100 lb; exact pound-to-kilogram conversion. Colonic ileus 0.022 mg/kg IV Colonic ileus 0.044 mg/kg SC, IM Colonic ileus 0.025 mg/kg SC Every 2–6 h Foal colonic distension 1–2 mg/animal SC Every 1 h Foals with C. perfringens type C-associated distension; 2-3 initial doses then as needed. Foals over 250 lb receive 2 mg.
Cattle Use / stage Dose Route Schedule Instructions Motility stimulation 0.022 mg/kg SC Motility stimulation 0.0220462262 mg/kg SC As needed 1 mg per 100 lb; exact pound-to-kilogram conversion.
Sheep Use / stage Dose Route Schedule Instructions Motility stimulation 0.022–0.033 mg/kg SC
Pigs Use / stage Dose Route Schedule Instructions Motility stimulation 0.044–0.066 mg/kg IM
Ruminant Use / stage Dose Route Schedule Instructions Rumen hypomotility 0.02 mg/kg IM, SC
Myasthenia gravis Neuromuscular blockade reversal Ileus and urinary retention Rumen hypomotility Antimyasthenic treatment Myasthenia diagnostic aid Motility stimulation Colonic ileus Foal colonic distension Mechanical urinary or intestinal obstruction Asthma or bronchoconstriction, pneumonia, or cardiac arrhythmias Bromide sensitivity applies to bromide formulations; additional bromide can accumulate with potassium bromide. Other cholinergic drugs increase toxicity; atropine and glycopyrrolate oppose muscarinic effects. Diarrhea, secretions, bradycardia, miosis, bronchoconstriction and muscle weakness. Excess cholinergic effects may require atropine and supportive treatment. Cholinergic crisis causes secretions, bronchospasm, bradycardia or tachycardia, weakness and possible respiratory paralysis. Stop treatment, distinguish from myasthenic deterioration, support ventilation and use atropine for muscarinic effects.
Preparation Form Strength Route Neostigmine bromide 15 mg Tablet 15 mg / tablet PO Neostigmine methylsulfate 0.25 mg/mL Injection 0.25 mg / mL IV, IM, SC Neostigmine methylsulfate 0.5 mg/mL Injection 0.5 mg / mL IV, IM, SC Neostigmine methylsulfate 1 mg/mL Injection 1 mg / mL IV, IM, SC
Monitor gastrointestinal signs, pulse and rhythm. Equine use may worsen abdominal discomfort; pyridostigmine is often preferred for ongoing myasthenia treatment.
A conflicting small-intestinal ileus report describes 2 mg per 500-kg adult horse SC or IV every 30-60 minutes to cumulative 10 mg; other guidance says no small-intestinal benefit. Keep cumulative and weight-qualified context; colic may worsen.
Protect neostigmine methylsulfate injection from light and freezing; bromide tablets remain a different salt.
