Pyridoxine (Vitamin B-6)
Pyridoxine hydrochloride
Also known as: Aminoxin · Vitelle Nestrex · Vitamin B6 · adermine · pyridoxal-5-phosphate · pyridoxamine · pirodoxamina · piridossima · piridoxolum · piridossina
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Isoniazid (INH) toxicity | If quantity of INH ingested is known, give pyridoxine on a mg for mg (1:1) basis. If it is not known, give pyridoxine initially at 71 mg/kg as a 5-10% IV infusion over 30-60 minutes | IV | Once | — | 🌎 NA |
| To replace pyridoxine antagonized by crimidine ingestion | 20 mg/kg | IV | Once | — | 🌎 NA |
| To delay the development of cutaneous toxicity (PPES) associated with doxorubicin containing pegylated liposomes (Doxil®) | 50 mg | PO | q8h (three times daily) | During chemotherapy protocol period | 🌎 NA |
- Isoniazid (INH) toxicity: Some sources say it can be given as an IV bolus. Do not use injectable B-complex vitamins.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| To replace pyridoxine antagonized by crimidine ingestion | 20 mg/kg | IV | Once | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Pyridoxine (Vitamin B6) is a water-soluble vitamin essential for numerous metabolic processes. In veterinary medicine, its primary specific indications are as an antidote for isoniazid (INH) or crimidine toxicity, and to delay cutaneous toxicity (palmar-plantar erythrodysesthesia) associated with liposomal doxorubicin (Doxil®).
Clinical Pearl: While dietary deficiency is extremely rare in dogs and cats consuming balanced commercial diets, cats with severe gastrointestinal disease may have increased requirements for pyridoxine. Additionally, in vitro studies have demonstrated that pyridoxine can suppress the growth of feline mammary tumors.
Mechanism of action
Pyridoxine is converted in erythrocytes to pyridoxal phosphate and, to a lesser extent, pyridoxamine, which act as vital coenzymes for protein, lipid, and carbohydrate utilization.
- Neurotransmitter Synthesis: Required for the synthesis of GABA (gamma-aminobutyric acid) in the CNS, and the conversion of tryptophan → serotonin or niacin.
- Metabolic Pathways: Essential for glycogen breakdown, heme synthesis, and the conversion of oxalate → glycine.
- Toxicity Antidote: Acts as an antidote by directly enhancing the renal excretion of cycloserine and isoniazid.
Safety & warnings
Contraindications
- Documented hypersensitivity or sensitivity to pyridoxine
Adverse effects
- Paresthesias (reported in humans)
- Somnolence (reported in humans)
- Reduced serum folic acid levels
- Peripheral neuropathy (associated with massive overdoses)
Precautions
Weigh potential risks versus benefits in patients with documented sensitivity to pyridoxine. While very safe at recommended doses during pregnancy, very large doses during pregnancy can cause a pyridoxine dependency syndrome in neonates. Pyridoxine requirements of the dam may be increased during nursing.
Drug interactions
May cause increased pyridoxine requirements
May cause increased pyridoxine requirements
May cause increased pyridoxine requirements
May cause increased pyridoxine requirements
May cause increased pyridoxine requirements
May cause increased pyridoxine requirements
Pyridoxine may reduce levodopa efficacy (no interaction when levodopa is used with carbidopa)
High dose pyridoxine may decrease phenobarbital serum levels
High dose pyridoxine may decrease phenytoin serum concentration
Monitoring
- Efficacy for intended use
- Neurologic signs (gait, coordination) if on high doses
Pharmacokinetics
Absorption
Absorbed from the GI tract primarily in the jejunum. Malabsorption syndromes can significantly impair pyridoxine absorption.
Distribution
Pyridoxine is not bound to plasma proteins, but its active metabolite pyridoxal phosphate is completely bound to plasma proteins. Stored primarily in the liver with smaller amounts stored in the brain and muscle.
Metabolism
Biotransformed in the liver and various tissues to active coenzymes.
Elimination
Excreted almost entirely as metabolites into the urine.
Overdose
Warning: While single overdoses are generally not problematic unless massive, chronic high doses can cause severe neurologic toxicity.
- Massive Acute Overdose: Laboratory animals given 3-4 grams/kg developed seizures and died.
- Chronic Overdose: Dogs (Beagles) repeatedly given 3 gram oral daily doses developed uncoordinated gait and neurologic signs. Neuronal lesions were noted in sensory, dorsal root ganglia, and trigeminal ganglia. Signs generally resolved over a 2-month drug-free period.
Available products
Formulations
- Enteric-coated tablets
- Injection
Veterinary
- No single ingredient veterinary-labeled pyridoxine products are available (found in combination products)
Human-labeled
- Pyridoxine Tablets: 50 mg, 100 mg, 250 mg, & 500 mg
- Pyridoxine (as pyridoxal-5'-phosphate) Tablets (enteric-coated): 20 mg (Aminoxin®)
- Pyridoxine HCl Injection: 100 mg/mL in 1 mL vials
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored below 40°C (104°F), preferably between 15-30°C (59-86°F), in well-closed containers protected from light. Injection should be stored at the same temperatures, protected from light and freezing. Injection can be administered undiluted or added to commonly used IV solutions. Compatible with doxapram and 10% fat emulsion. Incompatible with alkaline or oxidizing solutions, and iron salts.
Client information
Important: Pyridoxine is generally very safe, but extremely high doses can cause nerve damage.
- Do not exceed the dose prescribed by your veterinarian.
- Contact your veterinarian immediately if your pet develops any abnormal neurologic signs, such as difficulty walking, stumbling, or trouble using stairs.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.