The neurotoxicity of the rat poison vacor. A clinical study of 12 cases.

Oral ingestion of a new rat poison that antagonizes nicotinamide metabolism, N-3-pyridylmethyl-N'-p-nitrophenyl urea (PNU, Vacor), is known to cause diabetes mellitus. I describe neurologic complications of PNU ingestion in 12 patients 19 to 50 years of age who swallowed between 0.39 and 7.02 g of PNU. One died within a day, and five died of chronic complications 40 to 182 days after taking the poison. Apart from the acute hyperglycemic ketoacidosis, the clinical presentation was variable, but orthostatic hypotension, gastrointestinal hypomotility, peripheral neuropathy, and encephalopathy were typical. The peripheral, autonomic, and central-nervous dysfunction could develop either acutely or other several days. It is possible that nicotinamide, given parenterally within minutes, prevents toxicity, but the cases discussed in this paper indicate that the neurologic deficits may progress despite later nicotinamide administration. Neurologic improvement took many months. Full recovery was uncommon, and the orthostatic, hypotension tended to persist.