NEOSTIGMINE METHYLSULFATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Inhibits acetylcholinesterase at the neuromuscular junction, increasing acetylcholine availability and enhancing cholinergic transmission.
| Metabolism | Metabolized by microsomal enzymes in the liver; primarily hydrolyzed by cholinesterases. Minimal cytochrome P450 involvement. |
| Excretion | Renal excretion of unchanged drug accounts for approximately 50% of elimination; the remainder is metabolized by microsomal enzymes and excreted in urine as metabolites. Biliary/fecal elimination is minimal (<5%). |
| Half-life | Terminal elimination half-life is approximately 0.7 to 1.2 hours (mean 0.8 h) in healthy adults. In renal impairment, half-life may be prolonged up to 3-4 hours, requiring dose adjustment. |
| Protein binding | Approximately 15-25% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Volume of distribution is approximately 0.7-1.0 L/kg. This relatively moderate Vd indicates distribution primarily into extracellular fluid and some tissues. |
| Bioavailability | Oral bioavailability is very low (approximately 1-2%) due to extensive presystemic metabolism. Parenteral routes (IV, IM, SC) have 100% bioavailability. |
| Onset of Action | Intravenous: 1-3 minutes; Intramuscular: 10-30 minutes; Subcutaneous: 20-40 minutes; Oral: 45-75 minutes. |
| Duration of Action | Duration of clinical effect is 1-4 hours depending on dose and route. For reversal of neuromuscular blockade, effects last 60-120 minutes. In myasthenia gravis, duration of symptomatic improvement is 2-4 hours after oral administration. |
0.5-2.5 mg intravenously or intramuscularly every 2-4 hours as needed for reversal of neuromuscular blockade or treatment of myasthenia gravis; for reversal of non-depolarizing neuromuscular blockade, 0.03-0.07 mg/kg intravenously with anticholinergic.
| Dosage form | SOLUTION |
| Renal impairment | Creatinine clearance <50 mL/min: increase dosing interval to every 6-8 hours; severe impairment (CrCl <30 mL/min): use with caution, consider 50% dose reduction. |
| Liver impairment | No specific Child-Pugh based adjustments; use with caution in severe hepatic impairment due to potential increased exposure. |
| Pediatric use | 4-10 mcg/kg intramuscularly or subcutaneously for myasthenia gravis; for reversal of neuromuscular blockade: 0.03-0.07 mg/kg intravenously with atropine. |
| Geriatric use | Initiate at lower end of dosing range; monitor for bradycardia and excessive cholinergic effects; consider renal function adjustment. |
| 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 | Unknown if excreted in human milk. M/P ratio not reported. Use caution in nursing mothers; consider risk of gastrointestinal disturbances in infant. |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: limited human data, animal studies show potential for minor skeletal variations at high doses. Second and third trimesters: increased uterine contractility may occur; case reports suggest no major malformations. Caution in preterm labor due to possible cervical dilation. |
| Fetal Monitoring |
■ FDA Black Box Warning
Warning: Bradycardia, hypotension, and cardiac arrest have occurred when used to reverse neuromuscular blockade. Administer with an anticholinergic agent (e.g., atropine or glycopyrrolate) and monitor cardiac function.
| Common Effects | reversal of neuromuscular blockade |
| Serious Effects |
["Hypersensitivity to neostigmine or any component of the formulation","Peritoneal irritation or obstruction (for oral use in GI indications)","History of cholinergic crisis"]
| Precautions | ["May cause severe bradycardia and hypotension; co-administer with anticholinergic agent","Caution in patients with bradycardia, coronary artery disease, or recent myocardial infarction","Can increase gastric acid secretion; use cautiously in patients with peptic ulcer disease","May exacerbate asthma or COPD due to bronchoconstriction","Use in pregnancy only if clearly needed (no adequate well-controlled studies)"] |
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| Monitor fetal heart rate (FHR) and uterine activity during IV use due to risk of uterine hyperstimulation. Assess maternal vital signs and for signs of cholinergic excess. In myasthenia gravis, adjust dose based on muscle strength and awareness of increased clearance in pregnancy. |
| Fertility Effects | No reported detrimental effects on fertility. Animal studies show no impairment of fertility. Use for myasthenia gravis may allow maintenance of pregnancy. |