Histologic Findings in Rats Subjected to Prolonged Administration of Para-Aminobenzoic Acid

Summary

1. In doses greatly exceeding the usual therapeutic range for man, paraminobenzoic acid is a relatively non-toxic substance for the rat. 2. Aside from histologic alterations in the thyroid gland, no significant pathologic changes were detected in the treated animals or in their offspring. 3. The thyroid changes consisted of reduction in the amount and eosinophilia of intrafollicular colloid, associated with epithelial hypertrophy and hyperplasia. These findings were maximal after 2 months of treatment. 4. No hepatotoxic effect was detected.