STUDIES ON THE TOXICITY AND PHARMACOLOGY OF VITAMIN B₆ (2-METHYL-3-HYDROXY-4,5-BIS-(HYDROXYMETHYL)-PYRIDINE)

¹ From the Merck Institute for Therapeutic Research, Rahway, New Jersey

1. The L.D. 50 of vitamin B₆ hydrochloride in rats is 3.7 grams per kilogram following subcutaneous injection and 5.5 grams per kilogram following oral adminstration.

2. Doses above 1 gram per kilogram of vitamin B₆ produce toxic manifestations in dogs, rabbits, and rats characterized by impairment of the coordination and tonic convulsions. The dose required to produce these symptoms is at least 1000 times greater than the therapeutic dose.

3. Daily administration of vitamin B₆ over a period of 80 days to dogs (20 mgm. per kilogram) and rats (25 mgm. per rat) failed to produce any toxic manifestations or pathological changes of the organs. Rats receiving 2.5 mgm. daily were raised through three generations.

4. The urine of apparently healthy men and dogs contains less than 0.5 micrograms of vitamin B₆ per cubic centimeter as determined by bioassay.

5. The metabolism, the circulatory and respiratory system, and isolated smooth muscle organs of normal animals are not influenced by vitamin B₆.