Histological studies into rat liver following long-term application of aminophenazone, phenazone, and propyphenazone.

Morphological studies by means of light microscopy are important for toxicological drug testing. More complete information on potential damage can be obtained only by combination of pharmacological, biochemical, hepatofunctional, and morphological tests and studies. No systematic tests had been applied to rats, in the past. Therefore, aminophenazone, phenazone, and propyphenazone were tested for periods up to 16 weeks. Long-term application of the three pyrazolone derivatives resulted in the following dose-dependent and time-dependent alterations: hepatocyte enlargement, fatty degeneration and reactive-inflammatory changes along with single-cell necrosis, round cellular infiltration of periportal fields, and Kupffer cell activation. The alterations differed in intensity by the following order: aminophenazone greater than phenazone greater than propyphenazone.