What is the pyridoxine dose for isoniazid (INH) neuropathy prophylaxis?

Pyridoxine 10–25 mg/day orally for prophylaxis of isoniazid-induced peripheral neuropathy (all TB patients on INH). Higher risk patients (elderly, malnourished, alcoholics, diabetics, HIV-positive, renal failure): 25–50 mg/day. NTEP guidelines in India recommend pyridoxine 10 mg/day with all INH-containing regimens.

What is the dose of pyridoxine for hyperemesis gravidarum?

Pyridoxine 10–25 mg every 8 hours (30–75 mg/day) orally for nausea and vomiting of pregnancy. The combination of doxylamine 10 mg + pyridoxine 10 mg is recommended by ACOG/FOGSI. For severe hyperemesis requiring hospitalisation, pyridoxine 100 mg IV over 20 minutes can be utilized. Maximum safe long-term maternal dose: 100–200 mg/day.

Can high-dose pyridoxine cause toxicity?

Yes — paradoxically, high-dose pyridoxine (>500 mg/day, rarely >200 mg/day) causes progressive sensory axonopathy. Symptoms include sensory ataxia, paresthesia, and burning pain. Safe upper intake limit: 100 mg/day for chronic maintenance.

💊 Drug Dose Calculator

Vitamin B6 (Pyridoxine) Dose Calculator

Pyridoxine HCl · Pyridoxal-5-Phosphate (P5P) Oral, IV, IM — INH Neuropathy, Hyperemesis, Deficiency, Sideroblastic Anaemia

⚠️ Toxicity Warning: High-dose pyridoxine (>500 mg/day chronically, rarely >200 mg/day) can paradoxically CAUSE sensory neuropathy. Chronic therapeutic maintenance must not exceed 100 mg/day without clear specialist rationale.

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⚠️ Evidence-based guidance. Do not exceed 100 mg/day long-term without specific indication — pyridoxine neurotoxicity is a documented clinical risk. Always consult current product prescribing information.

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Pyridoxine (B6) — Clinical Overview

Form	Type	Key Feature	Best For	India Availability
Pyridoxine HCl	Standard form (prodrug)	Hepatic phosphorylation to P5P via pyridoxal kinase	All standard indications — INH prophylaxis, deficiency, NVP	Universal (Tablets, Multivitamins, Ampoules)
Pyridoxal-5-Phosphate (P5P)	Active coenzyme form	Bypasses hepatic conversion; functional cofactor	Hepatic impairment, alkaline phosphatase deficiency, refractory cases	Specialty brands & nutraceuticals

Isoniazid and Pyridoxine — Essential in TB Practice

Isoniazid (INH) forms inactive hydrazone complexes with pyridoxal phosphate and inhibits pyridoxal kinase, depleting active B6. NTEP/RNTCP guidelines mandate pyridoxine 10 mg/day for all patients on INH-containing regimens. High-risk cohorts (diabetic, malnourished, chronic kidney disease, pregnant, HIV-coinfected, elderly) require 25–50 mg/day.

Hyperemesis Gravidarum (NVP)

Pyridoxine 10–25 mg every 8 hours orally is the first-line pharmacotherapy for nausea and vomiting in pregnancy (ACOG/FOGSI guidelines). It can be combined with doxylamine 10 mg. In severe hyperemesis requiring hospitalization, an IV infusion of 100 mg over 20 minutes may be utilized alongside IV thiamine.

Pyridoxine Toxicity — Paradoxical Sensory Neuropathy

Chronic consumption exceeding 200–500 mg/day causes sensory ganglionopathy (dorsal root neuronopathy) presenting with numbness, sensory ataxia, and paresthesias. The tolerable upper intake level (UL) is 100 mg/day for adults.

Frequently Asked Questions

10 mg/day orally for standard TB patients on INH regimens. For high-risk individuals (malnourished, HIV-positive, CKD, diabetes, pregnancy), provide 25–50 mg/day. Established INH-induced neuropathy requires 100–200 mg/day until symptomatic resolution.

10–25 mg orally every 8 hours (30–75 mg/day). Often co-prescribed with doxylamine 10 mg. Severe inpatient refractory vomiting can receive 100 mg IV slowly over 20 minutes.

Yes. Prolonged high intake (>200–500 mg/day) causes symmetrical sensory axonal neuropathy. Keep chronic supplementation below the 100 mg/day adult ceiling unless treating specific metabolic dependency or acute intoxication.

A therapeutic trial of 100–200 mg/day for 2–3 months. If a reticulocyte and hemoglobin response occurs, titrate down to the lowest effective maintenance dose (often 25–50 mg/day).

Yes, high doses enhance peripheral decarboxylation of levodopa, reducing CNS entry. However, this does NOT happen when levodopa is co-administered with a dopa-decarboxylase inhibitor like carbidopa (e.g., Syndopa).

Disclaimer: For qualified healthcare practitioners only. Dosing protocols correspond with NTEP, ACOG, and WHO clinical literature. Clinical judgment and local formulary rules override automated calculations.