Prostigmin

Action

Inhibits enzyme acetylcholinesterase, leading to increased acetylcholine concentration at synapse and prolonged acetylcholine effects. Exerts direct cholinomimetic effect on skeletal muscle.

Availability

Injection (methylsulfate): 2 mg/ml, 1 mg/ml, 0.5 mg/ml, 0.25 mg/ml

Tablets (bromide): 15 mg

Indications and dosages

➣ Myasthenia gravis

Adults: 15 mg/day P.O.; may increase p.r.n. up to 375 mg/day; average dosage is 150 mg/day. Or 1 ml of 1:2,000 solution (0.5 mg) subcutaneously or I.M. based on response and tolerance.

➣ Postoperative abdominal distention and bladder atony

Adults: 0.5 to 1 mg I.M. or subcutaneously. If given for urinary retention and no response occurs within 1 hour, catheterize patient as ordered and repeat dose q 3 hours for five doses.

➣ Antidote for nondepolarizing neuromuscular blockers

Adults: 0.5 to 2.5 mg I.V.; repeat p.r.n. up to 5 mg. Precede initial dose with 0.6 to 1.2 mg atropine sulfate I.V., as ordered.

Contraindications

• Hypersensitivity to cholinergics or bromide

• Mechanical obstruction of GI or urinary tract

• Peritonitis

Precautions

Use cautiously in:

• asthma, peptic ulcer, bradycardia, arrhythmias, recent coronary occlusion, vagotonia, hyperthyroidism, seizure disorder

• pregnant or breastfeeding patients.

Administration

Before giving, ensure that atropine sulfate is available to treat cholinergic crisis.

• Know that atropine may be combined with usual neostigmine dose to decrease risk of adverse reactions.

• Give oral form 1 hour before or 2 hours after a meal.

• Administer I.V. dose undiluted directly into vein or I.V. line. Give 0.5-mg dose slowly over 1 minute.

Keep resuscitation equipment nearby.

Adverse reactions

CNS: dizziness, headache, drowsiness, asthenia, loss of consciousness

CV: hypotension, tachycardia, bradycardia, atrioventricular (AV) block, cardiac arrest

EENT: vision changes, lacrimation, miosis

GI: nausea, vomiting, diarrhea, abdominal cramping, flatulence, increased peristalsis

GU: urinary frequency

Musculoskeletal: muscle cramps, spasms, and fasciculations; joint pain

Respiratory: dyspnea, bronchospasm, respiratory depression, respiratory arrest, laryngospasm

Skin: rash, urticaria, flushing

Other: anaphylaxis

Interactions

Drug-drug. Aminoglycosides, anticholinergics, atropine, corticosteroids, local and general anesthetics: reversal of anticholinergic effects

Cholinergics: additive toxicity

Kanamycin, neomycin, streptomycin: increased neuromuscular blockade

Succinylcholine: potentiation of neuromuscular blockade, prolonged respiratory depression

Patient monitoring

Monitor vital signs. Assess patient for hypotension, bradycardia or tachycardia, AV block, and evidence of impending cardiac arrest.

• Evaluate respiratory and neurologic status.

Patient teaching

• Instruct patient to take tablets 1 hour before or 2 hours after meals.

Tell patient drug may alter his respiratory and cardiac status. Teach him to recognize and immediately report warning signs.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, vision, muscle function, and alertness.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.