Physostigmine


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Dementia in Alzheimer's disease Initial: 0.5 mg 2 hrly, 6 or 7 times/day. Max: 16 mg/day. Ophth Glaucoma As 0.25% sulfate oint or as 0.25/0.5% salicylate soln: Use as directed. IV/IM Reversal of anticholinergic effect Initial: 0.5-2 mg, may repeat every 20 mins until response or adverse effects occur. Stimulate peristalsis in postoperative intestinal atony 0.5-2 mg.
Dosage Details
Ophthalmic
Glaucoma
Adult: As sulfate, 0.25% ointment. As salicylate, 0.25% or 0.5% eye drops.

Oral
Alzheimer's dementia
Adult: Initial dose: 0.5 mg every 2 hr, 6 or 7 times daily until beneficial or adverse effects occur. Max dose: 16 mg/day.

Parenteral
Stimulate peristalsis in postoperative intestinal atony
Adult: Usual dose: 0.5-2 mg IV or IM inj.

Parenteral
Reversal of anticholinergic effect
Adult: Initial dose: 0.5-2 mg. May be given via slow IV inj or IM, repeated every 20 min until response or adverse effects occur. If initial doses are effective, additional doses of 1-4 mg may be given as necessary at usual intervals of 30-60 minutes as life-threatening signs recur.
Child: For life-threatening situations only: 0.02 mg/kg as initial dose. May be given via slow IV inj or IM, repeated at 5-10 min intervals until response or adverse effects occur or a total dose of 2 mg has been admin.
Contraindications
Acute iritis; acute uveitis; anterior uveitis; some forms of secondary glaucoma.
Special Precautions
Acute inflammatory disease of the anterior segment of the eye. Discontinue before eye surgery (risk of hyphema). History of retinal detachment, children with myopia. Night driving or hazardous task undertaken in poor illumination. Patients wearing soft contact lenses. Prolonged use may lead to depigmentation of the lid margins in dark-skinned patients.
Adverse Reactions
Systemic: CNS effects, may produce follicles in the conjunctiva, increased salivation, nausea, vomiting, abdominal cramps, diarrhoea, allergic reactions. Ophthalmic: Ciliary spasm, ocular pain and irritation, blurred vision, lachrymation, myopia, browache, conjunctival vascular congestion, superficial keratitis, vitreous haemorrhage, increased pupillary block, lens opacities (prolonged use).
Potentially Fatal: Respiratory failure.
Overdosage
May lead to "cholinergic crisis" which include excessive sweating, lachrymation, increased peristalsis, bradycardia and bronchospasm.
Drug Interactions
Aminoglycosides, clindamycin, colistin, cyclopropane, halogenated inhalational anaesthetics and atropine may antagonise the effects of physotigmine. Quinine, chloroquine, hydroxychloroquine, quinidine, procainamide, propafenone, lithium and β-blockers may reduce treatment efficacy. Prolonged bradycardia may occur when taken with β-blockers. May prolong the action of suxamethonium when used together.
Action
Description: Physostigmine is a reversible tertiary amine cholinesterase inhibitor, prolongs and intensifies physiological actions of acetylcholine.
Pharmacokinetics:
Absorption: Readily absorbed from the GI tract.
Distribution: Crosses the blood brain barrier.
Metabolism: Mainly by hydrolysis of the ester linkages by cholinesterases.
Excretion: Little excreted in urine.
Storage
Parenteral:
Store at 15-30°C.
Disclaimer: This information is independently developed by MIMS based on Physostigmine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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