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pyridostigmine (Mestinon, Regnonol, Kalymin)
Tradenames: Mestinon, Regonol.
Indications:
1) myasthenia gravis: to improve muscle strength
2) useful for reversal of neuromuscular block due to non-depolarizing neuromuscular blocking agents
Dosage:
1) myasthenia gravis:
a) oral: 60-120 mg PO TID
b) 2 mg IM or IV slowly every 2-3 hours
c) large doses should be given with 0.6-1.2 mg of atropine IV to counteract adverse muscarinic effects
d) sustained-release: 180 mg PO QD/BID
2) reversal of non-depolarizing neuromuscular blockade:
a) 10 to 20 mg slow IV
b) follow with 0.6-1.2 mg of atropine IV
Tabs: 60 mg.
Syrup: 60 mg/5 mL.
Sustained release: tabs 180 mg
Injection: 5 mg/mL (2 mL, 5 mL).
Pharmacokinetics:
1) quaternary ammonium salt that does NOT cross the blood brain barrier
2) after IV administration, muscle strength improves within 2-5 minutes & lasts 2-3 hours
3) onset of action is 15 minutes with IM injection
4) undergoes hydrolysis by cholinesterase
5) also metabolized in the liver by cyt P450
6) patients with severe myasthenia gravis metabolize & excrete the drug faster than patients with less severe disease
Adverse effects:
1) common (> 10%)
- diarrhea, increased sweating, increased salivation, nausea, epigastric cramping
2) less common (1-10%)
- urge to urinate, increased bronchial secretions, miosis, lacrimation
3) uncommon (< 1%)
- thrombophlebitis, bradycardia, AV block, seizures, headache, dysphoria, drowsiness, muscle spasms, diplopia, laryngospasm, respiratory paralysis, hypersensitivity, hyper-reactive cholinergic responses, weakness
4) other
- vomiting
- dyspnea
- bronchospasm
- irregular pulse
- palpitations
- muscular twitching
- hypotension (rare)
Drug interactions:
- does NOT antagonize depolarizing neuromuscular blockers
Mechanism of action:
1) reversible anticholinesterase
2) produces generalized cholinergic responses
a) miosis
b) increased tone of intestinal smooth muscle
c) bronchial constriction
d) increased salivary & sweat gland secretion
Interactions
drug interactions
drug adverse effects of cholinesterase inhibitors
General
cholinesterase inhibitor
neurologic agent
Properties
MISC-INFO: elimination route LIVER
pregnancy-category C
safety in lactation ?
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998