Sir.—Drs Johnson, Kubic, and Levitt presented an informative discussion of the toxic condition caused by accidental ingestion of N-3-pyridylmethyl N′-p-nitrophenyl urea (PNU, Vacor rat killer) (Journal 134:161-164, 1980). Their patient fortunately recovered, as has been the case with several children with PNU intoxication known to me. Because further studies1-5 of PNU have amplified the clinical and toxicological information presented in this article, I would like to add some comments to their report.
Among adult patients ingesting various doses of PNU, ketosis-prone hyperglycemia, orthostatic hypotension, gastrointestinal hypomotility, and peripheral neuropathy were prominent features in most cases; in some, signs of encephalopathy also developed.1 Orthostatic hypotension has been the most important lasting disability, whereas some of the other symptoms tended to improve. The neurological and diabetic complications may develop within hours or days after PNU ingestion and may progress in spite of administration of the proposed antidote, niacinamide.