Key points
- We recommend to consult your poison centre with the use of this antidote.
- It is important to administer pyridoxine without waiting for clinical signs of isoniazid poisoning.
- Benzodiazepines should be used together with pyridoxine for treating convulsions associated with isoniazid, hydrazine, and gyromitra poisoning; combining these treatments provides a synergistic effect.
- In case of a drug shortage, contact your poison centre. Crushed pyridoxine tablets administered via a nasogastric tube may be suggested in some cases. It is also recommended to keep your injectable pyridoxine stock even if it has expired.
+ Synonyms and other terms
- Pyridoxine hydrochloride
- Vitamin B6
+ Indications
- Prevention and treatment of seizures associated with isoniazid, mushroom species Gyromitra, and hydrazine poisoning.
- Adjuvant treatment of ethylene glycol poisoning.
+ Dosage
+ Pediatric Dose
- Hydrazine, isoniazid or gyromitra poisoning:
- 70 mg/kg IV (max 5 g) by slow IV infusion over 10 minutes or until convulsions cease. Convulsions will probably cease during the injection, and the rest of the dose may then be administered over the next 4 hours.
- The 70 mg/kg (max 5 g) dose may be repeated once if convulsions recur.
- Ethylene glycol poisoning (adjuvant treatment):
- 50 mg direct IV every 6 hours.
+ Adult Dose
- Hydrazine, isoniazid or gyromitra poisoning:
- 5 g by slow IV infusion over 10 minutes or until convulsions cease. Convulsions will probably cease during the injection, and the rest of the dose may then be administered over the next 4 hours.
- The 5 g dose may be repeated once if convulsions recur.
- Ethylene glycol poisoning (adjuvant treatment):
- 50 mg direct IV every 6 hours.
+ Renal Impairment
No data suggests that the dose should be modified for short-term use.
+ Hepatic Impairment
No data suggests that the dose should be modified for short-term use.
+ Hemodialysis Patient
- Pyridoxine is dialyzable.
- No data suggests that the dose should be modified for short-term use.
+ Pregnancy
- The safety of large doses has not been established, although small doses have been demonstrated to be safe.
- Do not hesitate to use pyridoxine during pregnancy if the expected toxic effects pose a significant risk of morbidity or mortality.
- No data suggests that the dose should be modified for short-term use.
+ Obese or Overweight Patient
No data suggests that the dose should be modified for short-term use.
+ Adverse effects
- No significant adverse events in acute use.
+ Monitoring
- Vital signs
- State of consciousness
- Convulsions
+ End of treatment
- Isoniazid, hydrazine or gyromitra poisoning: convulsions cease with no recurrence and correction of acidosis.
- Ethylene glycol poisoning: resolution of poisoning and correction of acidosis.
+ Special Notes on Administration
Intravenous Route (IV)
- Direct IV
- Administer the 100 mg/ml IV concentrated solution undiluted by direct IV at a maximum rate of 500 mg/min. (Newborns: Maximum rate of 50 mg/min).
- Slow IV infusion over 10 min
- During convulsions.
- Dilute the dose in a compatible solution.
- Administer over 10 min using a volumetric pump.
- Slow IV infusion over 4 h
- When the convulsions have ceased.
- Dilute the dose in a compatible solution.
- Administer over 4 hrs using a volumetric pump.
- Newborns: Caution: multidose pyridoxine vial contains 1.5% benzyl alcohol as a preservative. Risk of Gasping Syndrome.
Subcutaneous Route (SC)
- Administration route not recommended.
Intramuscular Route (IM)
- Possible alternative to IV in certain circumstances, consult your poison centre.
Intraosseous Route (IO)
- No data available.
Compatibility
Partial list only. Consult the pharmacist on duty at your health care facility.
- Compatible solutes: D5W, NS, RS.
- Y-site compatibility: Aminophylline, atracurium, atropine, benztropine, calcium (chloride and gluconate), chlorpromazine, digoxin, diphenhydramine, dobutamine, dopamine, ephedrine, epinephrine, esmolol, famotidine, fentanyl, standard heparin, regular insulin isoproterenol, labetalol, lidocaine, magnesium ( sulfate), mannitol, meperidine, metoclopramide, metoprolol, midazolam, morphine, MVI, naloxone, nitroglycerin, sodium nitroprusside, norepinephrine, ondansetron, phentolamine, phenylephrine, phytonadione (vitamin K1), potassium (chloride), procainamide, prochlorperazine, promethazine, propranolol, protamine, ranitidine succinylcholine, thiamin, vasopressin, verapamil.
- Y-site incompatibility: dantrolene, diazepam, folic acid, furosemide, pentobarbital, phenobarbital, phenytoin.
- Conflicting data with sodium bicarbonate. Pyridoxine is incompatible with alkaline solutions.
Stability
- 30 ml multidose vial contains 1.5% benzyl alcohol as a preservative. Store at room temperature (15°C -30°C). Protect from light. Stable for 28 days after first puncture.
- No stability data for dilute solutions. Use the solution as soon as possible after preparation. Protect infusions from light.
+ Available products
- Injectable pyridoxine hydrochloride USP, 100 mg/ml, Inj. Sol., multidose 30 ml vial, Mylan Pharmaceuticals DIN 02245215
Vitamin B6, 100mg/tablet, JAMIESON LABORATORIES LTD, Npn 329185
+ Amount required to treat a person weighting 70kg during 24 hours
- At least 20g.
+ References
Bateman, D. Nicholas, and Colin B. Page. 2016. “Antidotes to Coumarins, Isoniazid, Methotrexate and Thyroxine, Toxins That Work via Metabolic Processes.” British Journal of Clinical Pharmacology 81 (3):437–45.
Chen, Hsien-Yi, Timothy E. Albertson, and Kent R. Olson. 2016. “Treatment of Drug-Induced Seizures.” British Journal of Clinical Pharmacology 81 (3):412–19.
Kennedy, Ashleigh, and Tammi Schaeffer. 2016. “Pyridoxine.” In Critical Care Toxicology, edited by Jeffrey Brent, Keith Burkhart, Paul Dargan, Benjamin Hatten, Bruno Megarbane, and Robert Palmer, 34:1–4. Cham: Springer International Publishing.
Sharma, Adhi N., and Robert J. Hoffman. 2011. “Toxin-Related Seizures.” Emergency Medicine Clinics of North America 29 (1):125–39.
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