Pralidoxime


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : IV Organophosphorus poisoning As adjunct to atropine: Loading dose: 1,000-2,000 mg via infusion over 15-30 minutes or slow inj over at least 5 minutes, may repeat dose after 1 hour, then 10-12 hourly as needed. For intermittent infusion dosing, repeat dose 4-6 hourly as needed. Max intermittent infusion rate: 200 mg/minute. Administer as soon as the effects of atropine are observed. Maintain atropinisation for at least 48 hours. Anticholinesterase overdose Initial: 1,000-2,000 mg, followed by 500-1,000 mg/hour via infusion. Alternatively, repeat initial dose after 1 hour then 3-8 hourly as needed. IM Organophosphorus poisoning Mild: 600 mg, repeat 1-2 times every 15 minutes as needed, up to Max: 1,800 mg. Severe: 3 inj of 600 mg in rapid succession to a total dose of 1,800 mg. Persistent: May repeat the entire series (1,800 mg) starting approx 1 hour after administration of the last inj.
Dosage Details
Intramuscular
Organophosphorus poisoning
Adult: Mild: 600 mg, repeat 1-2 times every 15 minutes as needed, up to Max: 1,800 mg. Severe: 3 inj of 600 mg in rapid succession to a total dose of 1,800 mg. Persistent: May repeat the entire series (1,800 mg) starting approx 1 hour after administration of the last inj.
Child: <40 kg: Mild: 15 mg/kg/dose, repeated every 15 minutes as needed. Max: 45 mg/kg. Severe: 15 mg/kg/dose, repeated 2 times in rapid succession to a total dose of 45 mg/kg. Persistent: May repeat the entire series (45 mg/kg given in 3 divided doses) starting approx 1 hour after administration of the last inj. ≥40 kg: Same as adult dose.

Intravenous
Organophosphorus poisoning
Adult: As adjunct to atropine: Loading dose: 1,000-2,000 mg via infusion over 15-30 minutes or slow inj over at least 5 minutes, may repeat dose after 1 hour, then 10-12 hourly as needed. For intermittent infusion dosing, repeat dose 4-6 hourly as needed. Max intermittent infusion rate: 200 mg/minute. Administer as soon as the effects of atropine are observed. Maintain atropinisation for at least 48 hours.
Child: ≤16 years As adjunct to atropine: Loading dose: 20-50 mg/kg (Max: 2,000 mg/dose) via inj over 15-30 minutes, followed by 10-20 mg/kg/hour as continuous infusion. Alternatively, a repeat bolus of 20-50 mg/kg after 1 hour and repeated 10-12 hourly as needed.  >16 years Same as adult dose.

Intravenous
Anticholinesterase overdose
Adult: Initially, 1,000-2,000 mg, followed by 500-1,000 mg/hour via infusion. Alternatively, repeat initial dose after 1 hour then 3-8 hourly as needed.
Renal Impairment
Dose reduction may be needed.
Reconstitution
IV inj: Reconstitute vial labelled as containing 1,000 mg with 20 mL sterile water for inj to make 50 mg/mL solution. IV infusion: Further dilute reconstituted solution with 0.9% NaCl for inj to make a final concentration of 10-20 mg/mL. IM inj: Dilute vial labelled as containing 1,000 mg with 3.3 mL of sterile water for inj to a final concentration of approx 300 mg/mL.
Special Precautions
Patient with myasthenia gravis. Not indicated for the treatment of poisoning due to carbamate pesticides, phosphorus, inorganic phosphates, or organophosphates without anticholinesterase activity. Renal impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Myasthenic crisis, transient neuromuscular blockade (high doses); worsening of cholinergic effects in rapid IV inj (e.g. tachycardia, laryngospasm, muscle rigidity or paralysis, or cardiac arrest).
Eye disorders: Blurred vision, diplopia, impaired accommodation.
Gastrointestinal disorders: Nausea, vomiting.
Injury, poisoning and procedural complications: Inj site pain (IM).
Investigations: Transient increase in AST/ALT, and creatine phosphokinase.
Musculoskeletal and connective tissue disorders: Muscle weakness.
Nervous system disorders: Headache, dizziness, drowsiness, paralysis, seizures.
Renal and urinary disorders: Renal insufficiency.
Respiratory, thoracic and mediastinal disorders: Hyperventilation, apnoea.
Skin and subcutaneous tissue disorders: Maculopapular rash.
Vascular disorders: Hypertension.
IM/IV/Parenteral/SC: C
MonitoringParameters
Monitor blood pressure, heart rate, respiratory rate, muscle fasciculations and strength, pulse oximetry; fluid balance throughout therapy. Perform continuous ECG and haemodynamic monitoring.
Action
Description: Pralidoxime reactivates cholinesterase outside the CNS that had been inactivated by phosphorylation due to exposure to certain organophosphate pesticides by displacing the enzyme from its receptor sites. It removes the phosphoryl group from the active site of the inhibited enzyme by nucleophilic attack, regenerating active cholinesterase, and forming an oxime complex. It also slows the aging process of phosphorylated cholinesterase to non-reactivable form and detoxifies certain organophosphates by direct chemical reaction.
Pharmacokinetics:
Absorption: Poorly absorbed from the gastrointestinal tract. Time to peak plasma concentration: Approx 5-15 minutes (IV); approx 35 minutes (IM).
Distribution: Distributed throughout the extracellular water; limited distribution into the CNS.
Metabolism: Metabolised in the liver.
Excretion: Via urine (80%, as unchanged drug and metabolites). Elimination half-life: 74-77 minutes (apparent); 3-4 hours (poisoned patients).
Chemical Structure

Chemical Structure Image
Pralidoxime

Source: National Center for Biotechnology Information. PubChem Database. Pralidoximum, CID=135398747, https://pubchem.ncbi.nlm.nih.gov/compound/Pralidoximum (accessed on Jan. 23, 2020)

Storage
Store between 20-25°C.
References
Anon. Pralidoxime. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 23/12/2019.

Anon. Pralidoxime. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 23/12/2019.

Buckingham R (ed). Pralidoxime . Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. http://www.medicinescomplete.com. Accessed 23/12/2019.

Joint Formulary Committee. Pralidoxime Chloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 23/12/2019.

Protopam Chloride for Injection (Baxter Healthcare Corporation). U.S. FDA. https://www.fda.gov/. Accessed 23/12/2019.

Protopam Chloride Injection, Lyophilized Powder for Solution (Baxter Healthcare Corporation). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 23/12/2019.

Disclaimer: This information is independently developed by MIMS based on Pralidoxime 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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