The formation of methaemoglobin by 4-aminopropiophenone (PAPP) and 4-(N-hydroxy) aminopropiophenone.

Oral dosing of rats with the cyanide antidote 4-aminopropiophenone (PAPP), brought about peak methaemoglobin levels at 15-40 min, but peak levels were attained at at 15-25 min after intravenous dosing. After both oral and intravenous administration at equimolar doses, 4-(N-hydroxy)aminopropiophenone (PHAPP), the putative methaemoglobin-producing metabolite of PAPP, produced higher peak levels of methaemoglobin than PAPP. Plasma from rats injected with PAPP was capable of forming methaemoglobin when added to naive rat erythrocytes.

Summary of the toxicologic profile of iopentol.

Repeat dose toxicity studies, reproductive studies and mutagenicity studies were performed to assess the safety of iopentol. It is concluded that iopentol, a non-ionic contrast medium, is free from significant toxic effects.