[Determination of alphaxalone in serum and urine by gas-liquid chromatography. Application in anaesthesiological pharmacology (author's transl)].

The authors propose a simple and reliable method for determination of alphaxalone [3 alpha-hydroxy(5 alpha)pregnane 11,20 dione] in serum and urine, during long-duration anaesthesia using Althesin, mixture of alphaxalone and alphadolone acetate [21 acetoxy, 3 alpha-hydroxy(5 alpha)pregnane 11,20 dione]. If assays of alphadolone appear difficult and without any precision, because of numerous interferences, the determination of alphaxalone in serum and urine seems interesting for pharmacokinetic and metabolic investigation. We confirm the quick rate of disappearance of alphaxalone from blood, associated with a very active metabolism in the liver. The results show that it exists a relation between the concentration of alphaxalone in blood and the value of anaesthesia judged on clinical and electrical criteria. We cannot however conclude that Althesin presents a cumulative effect, because we used important amounts of anaesthetic agent.