Drug information of Pyridostigmine


Drug group:

A cholinesterase inhibitor with a slightly longer duration of action than neostigmine. It is used in the treatment of myasthenia gravis and to reverse the actions of muscle relaxants.

Mechanism of effect

Pyridostigmine inhibits acetylcholinesterase in the synaptic cleft by competing with acetylcholine for attachment to acetylcholinesterase, thus slowing down the hydrolysis of acetylcholine, and thereby increases efficiency of cholinergic transmission in the neuromuscular junction and prolonges the effects of acetylcholine.


Pyridostigmine is a parasympathomimetic and a reversible cholinesterase inhibitor. Since it is a quaternary amine, it is poorly absorbed in the gut and doesn't cross the blood-brain barrier. Pyridostigmine has a slightly longer duration of action than NEOSTIGMINE. It is used in the treatment of myasthenia gravis and to reverse the actions of muscle relaxants.


Half-Life: 1-2 hr (IV)

Onset: 15-30 min (PO/IM); 2-5 min (IV)

Duration: 6-8 hr (PO); 2-3 hr (IV)

Bioavailability: 10-20%

Distribution: ~19 L

Metabolism: Liver microsomal enzymes

Metabolites: 3-hydroxy-N-methylpyridinium

Total Body Clearance: 8.5-9.7 mL/min/kg

Excretion: Urine (80-90%)

Drug indications

Myasthenia gravis


    Usual Adult Dose for Nerve Agent Pretreatment

Soman pretreatment:
30 mg orally every 8 hours starting at least 8 hours before anticipated nerve gas exposure.

Pyridostigmine is not effective and should not be taken at the time of, or after exposure to, nerve agents. Immediate treatment with parenteral atropine and pralidoxime is required if nerve agent exposure occurs.

Pretreatment has been used for up to 14 to 21 days.

Pyridostigmine has also been used as nerve agent pretreatment (NAPP) against other substances. In animal studies, pretreatment, together with atropine and pralidoxime postexposure treatment, was effective in increasing survival after tabun and soman poisoning, variably effective against cyclosarin, and ineffective against sarin and VX.

Usual Adult Dose for Reversal of Nondepolarizing Muscle Relaxants

10 to 20 mg by slow IV injection.
Atropine sulfate 0.6 to 1.2 mg IV is recommended immediately before pyridostigmine injection.

Airway and ventilation should be maintained until recovery of normal respiration.

Usual Adult Dose for Myasthenia Gravis

Immediate-release tablets and syrup:
Initial dose: 60 mg orally 3 times daily.
Maintenance dose: Increase dose as needed in intervals of at least 48 hours. Results of dose adjustments may take several days to become apparent. Effective doses have range from 60 mg to 1500 mg per day in 3 to 6 divided doses.

Sustained-release tablets: 180 to 540 mg orally once or twice daily, not more often than 6-hour intervals. May be used with immediate-release tablets or syrup to provide accurate dose titration and optimal control of symptoms.

2 to 5 mg IM or slow IV every 2 to 3 hours. To supplement oral dosage pre- and postoperatively, during labor and postpartum, during myasthenic crisis (differentiate between cholinergic and myasthenic crisis before administering), or when oral therapy is not possible, one-thirtieth of the oral dose (i.e., 2 mg IV for every 60 mg oral) may be given.

The use of continuous IV infusions at rates of 2 to 4 mg/hour has been reported in the management of myasthenic crisis.

Usual Pediatric Dose for Reversal of Nondepolarizing Muscle Relaxants

Children: 0.1 to 0.25 mg/kg/dose IV preceded by atropine or glycopyrrolate

Airway and ventilation should be maintained until recovery of normal respiration.

Usual Pediatric Dose for Myasthenia Gravis

Myasthenia gravis: Dosage should be adjusted such that larger doses administered prior to time of greatest fatigue.

Neonatal: (A benzyl alcohol-free formulation should be used for neonates):
Oral: 5 mg every 4 to 6 hours
IM, IV: 0.05 to 0.15 mg/kg/dose

Oral: 7 mg/kg/day in 5 to 6 divided doses
IM, IV: 0.05 to 0.15 mg/kg/dose (maximum single dose: 10 mg)

Renal Dose Adjustments

Dose adjustments may be required in patients with renal insufficiency. The dose should be individually titrated to achieve optimum response.

Liver Dose Adjustments

Data not available



Caution in epilepsy, asthma, COPD, recent MI, hypertension, vagotonia, hyperthyroidism, dysrhythmia

Keep atropine and epinephrine immediately available to treat hypersensitivity reactions resulting from therapy

Injection unstable in alkaline solutions

If symptoms of excess cholinergic activity occur discontinue therapy

Anticholinesterase sensitivity may develop for brief or prolonged periods

Points of recommendation

Some medical conditions may interact with pyridostigmine . Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have heart problems (eg, heart block, slow heartbeat), a urinary tract infection, asthma, or kidney problems
  • Some MEDICINES MAY INTERACT with pyridostigmine . Tell your health care provider if you are taking any other medicines, especially any of the following:
  • Quinine or quinidine because effectiveness of pyridostigmine may be decreased
  • Succinylcholine because actions and side effects may be increased by pyridostigmine
  • This may not be a complete list of all interactions that may occur. Ask your health care provider if pyridostigmine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

Pregnancy level


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