PYRIDOSTIGMINE BROMIDE
Clinical safety rating: safe
Animal studies have demonstrated safety
Reversible acetylcholinesterase inhibitor, prolonging the action of acetylcholine at nicotinic and muscarinic receptors.
| Metabolism | Hepatic via hydrolysis by plasma esterases; minimal CYP450 involvement. |
| Excretion | Renal: 70-90% unchanged; biliary/fecal: minor (<10%) |
| Half-life | Terminal half-life: 1-2 hours (prolonged in renal impairment; up to 6 hours in anuria) |
| Protein binding | Minimal (<20%); primarily to albumin |
| Volume of Distribution | 1.1-1.4 L/kg (consistent with distribution into extracellular fluid) |
| Bioavailability | Oral: 10-20% (low due to poor absorption and first-pass metabolism) |
| Onset of Action | Oral: 30-45 minutes; IM: 10-20 minutes; IV: 1-5 minutes |
| Duration of Action | Oral: 3-6 hours; IM/IV: 2-4 hours (duration may be shorter in myasthenic crisis) |
Oral: 60-120 mg every 3-4 hours (max 360 mg/day). Intravenous: 0.1-0.25 mg/kg IV (max 10 mg per dose) for reversal of nondepolarizing neuromuscular blockade, given with glycopyrrolate or atropine. Intramuscular: 0.2-1 mg for postoperative urinary retention.
| Dosage form | SYRUP |
| Renal impairment | CrCl 30-60 mL/min: Administer 50-75% of normal dose every 4-6 hours. CrCl <30 mL/min: Administer 25-50% of normal dose every 6-8 hours. Hemodialysis: Supplement dose after dialysis may be needed. |
| Liver impairment | No specific adjustment recommended for Child-Pugh A or B. Use with caution in severe hepatic impairment (Child-Pugh C) due to potential for increased cholinergic effects. |
| Pediatric use | Neonates and infants: 5 mg/kg/dose intramuscular or subcutaneous. Children: Oral, 2 mg/kg/dose every 3-4 hours. Intravenous for myasthenia gravis: 0.05-0.15 mg/kg/dose (max 10 mg). |
| Geriatric use | Start at lower end of dosing range (e.g., oral 30-60 mg every 4-6 hours). Monitor for bradycardia, hypotension, and excessive muscarinic side effects. Adjust based on renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other cholinergic agents can have additive effects Can cause bradycardia and bronchospasm.
| Breastfeeding | Excreted in human milk in trace amounts. M/P ratio not well established. The American Academy of Pediatrics considers it compatible with breastfeeding. Caution advised; monitor infant for cholinergic effects (e.g., diarrhea, increased secretions). |
| Teratogenic Risk | Pregnancy Category C. No adequate well-controlled studies in pregnant women. In animal studies, pyridostigmine bromide did not show teratogenic effects at doses up to 10 times the maximum human dose. However, fetal harm cannot be ruled out. Use only if clearly needed. First trimester: theoretically risk but no reported malformations; second and third trimesters: may cause transient neonatal myasthenia gravis symptoms if used near term. |
■ FDA Black Box Warning
None.
| Common Effects | Nausea |
| Serious Effects |
Hypersensitivity to pyridostigmine or bromides; mechanical gastrointestinal or urinary obstruction; peritonitis.
| Precautions | Can cause cholinergic crisis (muscle weakness, excessive secretions, bradycardia). Use with caution in asthma, bradycardia, epilepsy, hyperthyroidism, peptic ulcer, and urinary obstruction. May cause seizures at high doses. |
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| Fetal Monitoring | Monitor maternal vital signs, respiratory function, muscle strength, and signs of cholinergic crisis. In pregnant women with myasthenia gravis, assess fetal movement, growth, and amniotic fluid volume. Nonstress test and biophysical profile may be considered. Monitor for preterm labor and neonatal myasthenia gravis. |
| Fertility Effects | No significant human data on fertility effects. Animal studies showed no impairment of fertility at recommended doses. |