Administration of Pyridoxine (Vitamin B6) as the Antidote to Isoniazid Intoxication

 

Pathophysiology:

(1) Isoniazid inactivates available body stores of pyridoxine.

(2) Depletion of pyridoxine results in depletion of GABA in the central nervous system.

(3) Depletion of GABA increases the patient's susceptibility to seizures and the risk for coma.

Dose of Isoniazid	Dose of Pyridoxine
known	1 gram pyridoxine is administered for each 1 gram of isoniazid ingested (one to one)
unknown	5 gram pyridoxine is given every 10 minutes

 

Sources of pyridoxine:

(1) intravenous preparation with 1 gram in 10 mL vial

(2) chemical - Prepare a 10% solution (weight per volume) in D5W, filter through a 0.45 micron filter, then infuse.

(3) tablets - Crush and prepare a slurry that is given enterally.

 

Very high doses of pyridoxine may be associated with:

(1) tachypnea

(2) seizures

(3) abnormalities in postural reflexes

 

Doses of up to 52 grams have been given IV without adverse effects.