Clearance tests to assess liver function state of animals using compounds with high hepatic metabolism

The article is devoted to the study of the medicinal substances metabolism in the liver and the possibility of using clearance tests with lidocaine and caffeine in veterinary medicine. It has been established that liver is the main organ where metabolism takes place, which is carried out in two stages involving the reactions of microsomal oxidation of fermentable cytochrome P450. Substances with a high metabolic rate undergo presystemic elimination. In liver pathologies, the metabolism of xenobiotics changes, substances with a high metabolism can cause toxic effects with a single application, with a low one – with cumulation. Intravenous clearance test with lidocaine showed that the lower the concentration of metabolites after 15 and 30 minutes, the more unfavorable the prognosis for survival. The test can also be used on dogs. The clearance test with caffeine can be performed intravenously, by respiratory methods or through saliva sampling. The test showed results comparable to the lidocaine test. However, clearance tests are influenced by many factors, so researchers recommend using them as an additional research method.