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Mestinon, Mestinon-SR (CA), Mestinon Timespan, Regonol
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.
Mestinon SR(trade name),
Mestinon Timespan(trade name),
- Increased intestinal and skeletal muscle tone,
- Bronchial and ureteral constriction,
- Increased salivation,
Time/action profile (cholinergic effects)
|PO||30–35 min||unknown||3–6 hr|
|PO-SR||30–60 min||unknown||6–12 hr|
|IM||15 min||unknown||2–4 hr|
|IV||2–5 min||unknown||2–3 hr|
Adverse Reactions/Side Effects
Central nervous system
- seizures (life-threatening)
Ear, Eye, Nose, Throat
- bronchospasm (most frequent)
- excessive secretions (most frequent)
- bradycardia (most frequent)
- abdominal cramps (most frequent)
- diarrhea (most frequent)
- excessive salivation (most frequent)
- nausea (most frequent)
- vomiting (most frequent)
- sweating (most frequent)
Drug-Drug interactionCholinergic effects may be antagonized by other drugs possessing anticholinergic properties, including antihistamines, antidepressants, atropine, haloperidol, phenothiazines, procainamide, quinidine, or disopyramide.Prolongs the action of depolarizing muscle-relaxing agents and cholinesterase inhibitors (succinylcholine, decamethonium ).↑ toxicity with other cholinesterase inhibitors, including echothiophate.
Prevention of Soman Nerve Gas Effects
Availability (generic available)
- Assess pulse, respiratory rate, and BP before administration. Report significant changes in heart rate.
- Myasthenia Gravis: Assess neuromuscular status, including vital capacity, ptosis, diplopia, chewing, swallowing, hand grasp, and gait before administering and at peak effect. Patients with myasthenia gravis may be advised to keep a daily record of their condition and the effects of this medication.
- Assess patient for overdose, underdose, or resistance. Both have similar symptoms (muscle weakness, dyspnea, dysphagia), but symptoms of overdosage usually occur within 1 hr of administration, whereas symptoms of underdose occur ≥3 hr after administration. Overdose (cholinergic crisis) symptoms may also include increased respiratory secretions and saliva, bradycardia, nausea, vomiting, cramping, diarrhea, and diaphoresis. A Tensilon test (edrophonium chloride) may be used to differentiate between overdosage and underdosage.
- Antidote to Nondepolarizing Neuromuscular Blocking Agents: Monitor reversal of effect of neuromuscular blocking agents with a peripheral nerve stimulator. Recovery usually occurs consecutively in the following muscles: diaphragm, intercostal muscles, muscles of the glottis, abdominal muscles, limb muscles, muscles of mastication, and levator muscles of eyelids. Closely observe patient for residual muscle weakness and respiratory distress throughout the recovery period. Maintain airway patency and ventilation until recovery of normal respirations occurs. Atropine is the antidote.
Potential Nursing DiagnosesImpaired physical mobility (Indications)
Ineffective breathing pattern (Indications)
- For patients who have difficulty chewing, pyridostigmine may be administered 30 min before meals.
- Oral dose is not interchangeable with IV dose. Parenteral form is 30 times more potent.
- When used as an antidote to nondepolarizing neuromuscular blocking agents, atropine may be ordered before or currently with large doses of pyridostigmine to prevent or to treat bradycardia and other side effects.
- Oral: Administer with food or milk to minimize side effects. Extended-release tablets should be swallowed whole; do not crush, break, or chew. Regular tablets or syrup may be administered with extended-release tablets for optimum control of symptoms. Mottled appearance of sustained-release tablet does not affect potency.
- pH: 6.0–7.0.
- Administer undiluted. Do not add to IV solutions. May be given through Y-site of infusion of D5W, 0.9% NaCl, LR, D5/Ringer’s solution, or D5/LR. Concentration: 5 mg/mL.
- Rate: For myasthenia gravis, administer each 0.5 mg over 1 min. For reversal of nondepolarizing neuromuscular blocking agents, administer each 5 mg over 1 min.
- Syringe Compatibility: glycopyrrolate
- Y-Site Compatibility: heparin, hydrocortisone sodium succinate, potassium chloride, vitamin B complex with C
- Instruct patient to take medication as directed. Do not skip or double up on missed doses. Patients with a history of dysphagia should have a nonelectric or battery-operated back-up alarm clock to remind them of exact dose time. Patients with dysphagia may not be able to swallow medication if the dose is not taken exactly on time. Taking dose late may result in myasthenic crisis. Taking dose early may result in cholinergic crisis. Patients with myasthenia gravis must continue this regimen as a life-long therapy.
- Advise patient to carry identification describing disease and medication regimen at all times.
- Instruct patient to space activities to avoid fatigue.
- Relief of ptosis and diplopia; improved chewing, swallowing, extremity strength, and breathing without the appearance of cholinergic symptoms.
- Reversal of nondepolarizing neuromuscular blocking agents in general anesthesia.
- Prevention of Soman nerve gas toxicity.