The development of a ¹³C-aminopyrine demethylation blood test in dogs and cats

Abstract

Previously, a function test that is both specific and sensitive for the assessment of hepatic function was not available. The studies presented in this thesis were performed as first steps in the development of a ¹³C-aminopyrine demethylation blood test for evaluation of hepatic function in dogs and cats. A preliminary study in dogs demonstrated that there was a detectable increase in percent dose (PCD) of ¹³CO₂ of the ¹³C administered as ¹³C-aminopyrine and recovered in gas extracted from blood samples. Pharmacokinetic studies were conducted in nine clinically healthy dogs and eight clinically healthy cats, respectively, in order to determine an optimal time point for sample collection after ¹³C-aminopyrine administration in both species. Also, dose studies were performed in the same 9 clinically healthy dogs and 8 clinically healthy cats in order to determine an optimal dose of ¹³C-aminopyrine to be administered in both species. In clinically healthy dogs, a 2 mg/kg dose is suitable for use and samples should be collected 45 min after intravenous ¹³C-aminopyrine administration. In clinically healthy cats, a 1 mg/kg dose is suitable for use and samples should be collected 90 min after intravenous ¹³C-aminopoyrine administration. In conclusion, ¹³C-aminopyrine demethylation testing appears safe in clinically healthy dogs and cats and leads to reproducible elevations in demethylation of ¹³C-aminopyrine.