Neostigmine

Neostigmine is a Cholinergic drug (Cholinesterase inhibitor or Anticholinesterase or Cholinomimetic).

Physostigmine and neostigmine are both cholinergic drugs, but they have a difference. Physostigmine can pass through the blood-brain barrier (BBB), reaching the brain directly, while neostigmine cannot cross BBB.

Group

Neostigmine is grouped as a Cholinergic drug, Cholinesterase inhibitor, Cholinomimetic, or Anticholinesterase.

Mechanism of Action

Neostigmine blocks the acetylcholinesterase (AChE) enzyme, which normally breaks down acetylcholine (ACh). When acetylcholinesterase is inhibited, acetylcholine isn’t broken down, leading to prolonged acetylcholine action at the synapse. So ultimately, the function of neostigmine is the same as that of acetylcholine.

Neostigmine is not absorbed when given orally. It is metabolised in the liver, hydrolyzed by plasma cholinesterase, and excreted in urine.

Dose Rates

The dose rate of neostigmine for animals is mentioned below:

• Dog: 0.02 to 0.04 mg/kg IV, IM, SC, PO
• Cat: 0.02 to 0.04 mg/kg IV, IM, SC, PO
• Horse: 0.02 to 0.04 mg/kg IV, IM, SC, PO
• Cattle: 0.02 mg/kg IV, IM, SC, PO
• Sheep: 0.02 to 0.03 mg/kg IV, IM, SC, PO
• Goat: 0.02 to 0.03 mg/kg IV, IM, SC, PO
• Swine or Pig: 0.04 to 0.06 mg/kg IV, IM, SC, PO

Indications

Neostigmine is used for the following conditions in animals:

• As an antidote for anticholinergic (atropine) toxicity
• For treatment of myasthenia gravis
• For the treatment of neuromuscular blockade
• For the treatment of ileus (neostigmine increases GI motility and treats functional ileus)
• For stimulation of ruminal motility in large animals
• For stimulation of gastrointestinal motility (but not affect stomach emptying) in small animals
• For the treatment of urinary retention

Contraindications

• Do not use Neostigmine if the animal is suffering from urinary or intestinal obstruction, asthma, bronchoconstriction, pneumonia, epilepsy, peptic ulcers, and arrhythmias. Neostigmine is also contraindicated in late pregnancy.

Interactions

• Neostigmine should not be used together with other cholinergic drugs (like Physostigmine); it aggravates the effect.
• Anticholinergics (like atropine) also should not be administered with it because that decreases the effect of Neostigmine.

Adverse effects

Side effects or adverse effects are miosis, bradycardia, muscle twitching, weakness, constriction of the bronchi and ureters, etc.

Toxicity

The toxicity of Neostigmine causes diarrhoea, increased GI secretions, and smooth muscle contractions.

This toxicity can be treated with anticholinergic drugs such as atropine.

Preparations

Neostigmine methylsulfate formulations are available in 0.5 mg/mL preparations in ampoules for parenteral injection. 15 mg of Neostigmine bromide tablet form is available for oral administration.

Here are some of the most widely known injection preparations:

• Neon Myostigmin 2.5 mg ampoule (0.5 mg/mL)
• Aesmira Stigmerase 2.5 mg ampoule (0.5 mg/mL)
• Myostigmin 2.5 mg ampoule (0.5 mg/mL)
• NEOFAV 0.5 mg ampoule (0.5 mg/mL)

Here are some of the most widely known tablet preparations:

• Neostigmine 15 mg tablets
• Tilstigmin 15 mg tablets
• Prostigmin 15 mg tablets

More about Neostigmine for animals