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Pharmacologic class: Anticholinesterase
Therapeutic class: Muscle stimulant, antimyasthenic
Pregnancy risk category C
Prevents acetylcholine destruction, resulting in stronger contractions of muscles weakened by myasthenia gravis or curare-like neuromuscular blockers
Injection: 5 mg/ml
Syrup: 60 mg/5 ml
Tablets: 60 mg
Tablets (extended-release): 180 mg
Indications and dosages
➣ Myasthenia gravis
Adults: 600 mg P.O. given over 24 hours, with doses spaced for maximum symptom relief. For myasthenic crisis, 2 mg or 1/30 of oral dose I.M. or very slow I.V. q 2 to 3 hours.
➣ Postoperative reversal of nondepolarizing neuromuscular blockers
Adults: 10 to 20 mg slow I.V. injection (range is 0.1 to 0.25 mg/kg) with or immediately after 0.6 to 1.2 mg atropine sulfate I.V.
• Renal impairment
• Seizure disorders
• Myasthenia gravis in children
• Constipation in patients with Parkinson's disease
• Nerve agent prophylaxis
• Hypersensitivity to drug or bromides
• Mechanical intestinal or urinary tract obstruction
Use cautiously in:
• seizure disorders, bronchial asthma, coronary occlusion, arrhythmias, bradycardia, hyperthyroidism, peptic ulcer, vagotonia, cholinergic crisis
• pregnant or breastfeeding patients
• children (safety and efficacy not established).
☞ Don't exceed I.V. injection rate of 1 mg/minute.
☞ Don't give concurrently with other anticholinesterase drugs.
• Have atropine available for use in emergencies.
CNS: headache, dysarthria, dysphoria, drowsiness, dizziness, headache, syncope, loss of consciousness, seizures
CV: decreased cardiac output leading to hypotension, bradycardia, nodal rhythm, atrioventricular block, cardiac arrest, arrhythmias
EENT: diplopia, lacrimation, miosis, spasm of accommodation, conjunctival hyperemia
GI: nausea, vomiting, diarrhea, abdominal cramps, increased peristalsis, flatulence dysphagia, increased salivation
GU: urinary frequency, urgency, or incontinence
Musculoskeletal: muscle weakness, fasciculations, and cramps; joint pain
Respiratory: increased pharyngeal and tracheobronchial secretions, dyspnea, central respiratory paralysis, respiratory muscle paralysis, laryngospasm, bronchospasm, bronchiolar constriction
Skin: diaphoresis, flushing, rash, urticaria
Other: thrombophlebitis at I.V. site, cholinergic crisis, anaphylaxis
Drug-drug. Aminoglycosides: potentiation of neuromuscular blockade
Anesthetics (general and local), antiarrhythmics: decreased anticholinesterase effects
Atropine, belladonna derivatives: suppression of parasympathomimetic GI symptoms (leaving only fasciculations and voluntary muscle paralysis as signs of anticholinesterase overdose)
Corticosteroids: decreased anticholinesterase effects; after corticosteroid withdrawal, increased anticholinesterase effects
Ganglionic blockers (such as mecamy-lamine): increased anticholinesterase effects
Magnesium: antagonism of beneficial anticholinesterase effects
Nondepolarizing neuromuscular blockers (atropine, pancuronium, tubocurarine): antagonism of neuromuscular blockade and reversal of muscle relaxation after surgery (with parenteral pyridostigmine)
Other anticholinesterase drugs: in patients with myasthenia gravis, symptoms of anticholinesterase overdose that mimic underdose, causing patient's condition to worsen
Succinylcholine: increased and prolonged neuromuscular blockade (including respiratory depression)
• Assess patient's response to each dose.
• Monitor vital signs, ECG, and cardiovascular and respiratory status.
☞ Assess for signs and symptoms of overdose, which indicate cholinergic crisis.
• If patient is using syrup, advise him to pour it over ice.
• Instruct patient using extended-release tablets not to crush them.
☞ Teach patient to recognize and promptly report signs and symptoms of overdose, including muscle fasciculations, sweating, excessive salivation, and constricted pupils.
• Tell patient drug may cause headache and muscle cramps. Encourage him to discuss activity recommendations and pain management with prescriber.
• Advise patient to monitor and report his response to ongoing therapy so that optimal dosage can be determined.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.
MestinonAn oral agent used to manage myasthenia gravis.
• Muscarinic—Nausea, vomiting, diarrhoea, abdominal cramps, increased peristalsis, increased salivation, increased bronchial secretions, miosis, diaphoresis; reversed with atropine.
• Nicotinic—Muscle cramps, fasciculation and weakness.