Neostigmine

Anticholinesterase for large colon impaction and post-operative GI ileus in horses; reversal of non-depolarizing neuromuscular blockade. Reversible anticholinesterase agent (neostigmine methylsulfate). Mechanism: inhibits acetylcholinesterase → prevents hydrolysis of acetylcholine → increased ACh at NMJ (reverses neuromuscular blockade) and at smooth muscle M3 receptors (increases GI motility). Used for large colon impaction (ileus) in horses. Quaternary ammonium — poor CNS penetration. Key information Acetylcholinesterase inhibitor. Have atropine available as antidote. Parasympathomimetic effects — increased salivation, miosis, GI motility. Do NOT use in animals with GI or urinary obstruction.

SQ injection: administer SQ — do not give IV (too rapid onset, severe cholinergic effects). Horses (GI motility): administer SQ for impaction colic — monitor for abdominal pain response. Atropine must be available as antidote. Onset: 10–30 min (SQ). Store at room temperature; protect from light. If a dose is missed This medication is administered by a veterinarian or veterinary staff in a clinical setting. Missed doses are managed by your veterinary team — contact your veterinarian to reschedule.

Cholinergic excess: excessive salivation, lacrimation, urination, defecation, bradycardia, bronchospasm, muscle fasciculations, abdominal cramping (SLUDGE signs). Overdose: cholinergic crisis. Colic worsening if mechanical obstruction present in horses. Contraindicated with GI obstruction.

For animals CONTRAINDICATED in patients with GI or urinary obstruction — will worsen obstruction. Avoid in patients with bronchospasm. For colic in horses: rule out mechanical obstruction before use; have atropine available as antidote. Monitor closely for 30 min after administration. For people handling this medication Wear gloves when handling. Wash hands thoroughly with soap and water after handling. Anticholinesterase — avoid skin contact. If accidentally injected, seek emergency medical attention (cholinergic crisis). Keep out of reach of children. Atropine is the antidote.

Contact your veterinarian. Neostigmine overdose causes cholinergic crisis: bradycardia, excessive secretions, GI cramping, and bronchospasm. Antidote: atropine by veterinary staff.