Actions of Sodium Bismuthate. ∗

Abstract

The bismuth compounds in current use contain the bismuth as cation, or in basic form, and do not dependably penetrate the brain and appear in the cerebrospinal fluid. Compounds containing the bismuth as anion, or in acid form, have not been tried previously, but, on theoretical grounds, might be expected to penetrate the central nervous system more readily than those containing bismuth as cation, and thus be more valuable in neurosyphilis. Accordingly, we have explored the possibilities of sodium bismuthate and obtained results worthy of record at this time in order to indicate the desirability of further study of anionic bismuth.

Sodium bismuthate (NaBiO₃) is the sodium salt of bismuthic acid with a bismuth content of 74.5%. It is obtainable in the market as a yellowish brown powder and possesses very low solubility in all ordinary and special solvents. The solubility in water and 0.9% sodium chloride solution is about 1:10,000, and in whole serum, 1:5,000, and sufficient liberation of bismuth occurs to give a darkening with sulphide. The reaction of the watery suspension (marketed product) is strongly alkaline. Strong mineral acids and 85% lactic acid dissolve bismuthate readily, but weak organic acids (citric and acetic) only slightly.

The toxicity of bismuthate was found to be very low. Rabbits (5) tolerated doses of from 0.6 to 1 gm. per kilo intramuscularly, and mice and rats (9), from 42 to 90 mgm. per kilo hypodermically. A fatal dose has not been found. The compound has been injected as a suspension in water or in acacia solution, without evidence of irritation. Three rabbits receiving 0.018 gm. per kilo intravenously and 0.22 and 0.6 gm. per kilo intramuscularly, excreted variable though considerable daily quantities of bismuth (about 1.4 mgm.) in urine over long periods (up to 4 months), the absorption being slow and continuous.