Adult: For the reversal of effects of nondepolarising neuromuscular blocking agents: 0.1-0.25 mg/kg (approx 10-20 mg) via IV inj. Atropine or glycopyrronium bromide IV must be given immediately before or simultaneously with pyridostigmine bromide.
Adult: As conventional tab: 60-240 mg daily. Dosing frequency may vary according to patient's needs. Child: As conventional tab: 15-60 mg daily. Dosing frequency may vary according to patient's needs.
Oral Myasthenia gravis
Adult: Dosage and dosing frequency must be individualised, considering severity of symptoms and patient's tolerability. As conventional tab or oral solution: Usual total daily dose: 300-1,200 mg; higher doses may be needed by some patients. Doses are divided throughout the day, given when maximum strength is needed (e.g. on rising and before mealtimes). Total daily doses higher than 450 mg may be associated with increased side effects. As extended-release tab: 180-540 mg once daily or bid (with at least 6 hours interval between doses). Recommendations may vary among individual products and between countries (refer to specific product guidelines). Child: As conventional tab or oral solution: <6 years Initially, 30 mg; 6-12 years Initially, 60 mg. May increase doses in increments of 15-30 mg daily until a satisfactory response is achieved. Usual total daily dose: 30-360 mg. Dosage recommendations may vary among individual products and between countries (refer to specific product guidelines).
Renal Impairment
Lower initial doses may be required; titrate to desired effect.
Administration
May be taken with or without food. ER tab: Swallow whole & do not break/crush/chew. Oral soln: For patients w/ difficulty swallowing, may be administered via feeding tubes. Consult product literature for specific recommendations.
Contraindications
Mechanical gastrointestinal or urinary obstruction.
Special Precautions
Patient with bradycardia or cardiac arrhythmia, recent coronary occlusion, hypotension, vagotonia; bronchial asthma, COPD; epilepsy or parkinsonism, hyperthyroidism, peptic ulcer, glaucoma, bromide sensitivity. Requirement for pyridostigmine bromide may be reduced following thymectomy. Renal impairment. Neonates, children, and elderly. Pregnancy and lactation.
This drug may impair visual acuity and consequently affect the ability to react, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor blood pressure and heart rate and obtain ECG, especially with IV use. Assess for signs and symptoms of cholinergic reactions (e.g. nausea, vomiting, diarrhoea, increased salivation), particularly when administered via IV.
Overdosage
Symptoms: Cholinergic crisis manifested as nausea, vomiting, diarrhoea, abdominal cramps, increased peristalsis, excessive salivation, sweating, increased bronchial secretions, miosis, lacrimation, blurred vision, bradycardia or tachycardia, bronchospasm, cardiospasm, hypotension, incoordination, muscle cramps, weakness, fasciculation, and paralysis. CV and respiratory failure may also occur. Agitation, restlessness, confusion, visual hallucinations, and paranoid delusions may occur at extremely high doses. Management: Maintain an adequate airway. If respiration is severely depressed, artificial ventilation must be initiated. Administer 1-2 mg of atropine via IV to control muscarinic effects, may repeat dose every 5-30 minutes as needed.
Drug Interactions
Requirement for pyridostigmine bromide may be reduced with corticosteroids and immunosuppressant drugs. Antagonised muscarinic effect with atropine and hyoscine. Pyridostigmine bromide antagonises the effect of nondepolarising muscle relaxants (e.g. pancuronium bromide, vecuronium bromide). May prolong the effect of depolarising muscle relaxants (e.g. suxamethonium). May enhance the bradycardic effect of β-blockers. May cause or exacerbate night vision problems with antiglaucoma agents.
Action
Description: Mechanism of Action: Pyridostigmine bromide, a quaternary ammonium compound, is a reversible cholinesterase inhibitor. It inhibits the destruction of acetylcholine by acetylcholinesterase, thereby facilitating transmission of nerve impulses across the neuromuscular junction. Onset: Myasthenia gravis: Within 30 minutes (oral [conventional tab]). Reversal of nondepolarising neuromuscular blocking agents: Approx 6 minutes (IV). Duration: 3-6 hours (oral [conventional tab]); 2-3 hours (IV). Pharmacokinetics: Absorption: Poorly absorbed from the gastrointestinal tract. Bioavailability: 10-20%. Time to peak plasma concentration: 1-2 hours (oral). Distribution: Poor penetration into the CNS. Crosses the placenta and enters breast milk. Volume of distribution: 0.53-1.76 L/kg. Metabolism: Metabolised in the liver and undergoes hydrolysis by cholinesterases to 3-hydroxy-N-methylpyridinium (main metabolite) and other unidentified metabolites. Excretion: Via urine (approx 80-90% as unchanged drug). Elimination half-life: 1-2 hours (oral [conventional tab]); approx 1.5 hours (IV).
Chemical Structure
Pyridostigmine bromide Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 7550, Pyridostigmine Bromide. https://pubchem.ncbi.nlm.nih.gov/compound/Pyridostigmine-Bromide. Accessed Feb. 23, 2024.
Storage
Store below 30°C. Protect from light and moisture. Storage recommendations may vary among individual products. Refer to specific product guidelines.
N07AA02 - pyridostigmine ; Belongs to the class of anticholinesterase. Used as parasympathomimetics.
References
Anon. Pyridostigmine (Pediatric and Neonatal Lexi-Drugs). Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 12/01/2024.Anon. Pyridostigmine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 19/10/2023.Anon. Pyridostigmine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 12/01/2024.Buckingham R (ed). Pyridostigmine Bromide. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/10/2023.iNova Pharmaceuticals (New Zealand) Limited. Mestinon 60 mg Tablets data sheet 10 May 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 03/10/2023.Joint Formulary Committee. Pyridostigmine Bromide. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 03/10/2023.Mestinon 60 mg Tablets (Mylan Products Ltd). MHRA. https://products.mhra.gov.uk. Accessed 03/10/2023.Mestinon Dragees 60 mg; Mestinon Tablet 10 mg (A. Menarini Singapore Pte. Ltd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/10/2023.Mestinon Solution, Tablet, and Tablet, Extended Release (Bausch Health US, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/10/2023.Paediatric Formulary Committee. Pyridostigmine Bromide. BNF for Children [online]. London. BMJ Group, Pharmaceutical Press, and RCPCH Publications. https://www.medicinescomplete.com. Accessed 12/01/2024.Pyridostigmine Bromide 12 mg/mL Oral Solution (Horizon Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 03/10/2023.Pyridostigmine Bromide Solution (Athem LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/10/2023.Pyridostigmine Bromide Tablet (Amneal Pharmaceuticals of New York LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 12/01/2024.Pyridostigmine Bromide Tablet, Extended Release (Alvogen, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 12/01/2024.Pyridostigmine. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 12/01/2024.Pyrimine Tablet 60 mg (Prestige Pharma Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 03/10/2023.Regonol Injection, Solution (Sandoz Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 03/10/2023.
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