Pharmacokinetics and effects of succinylcholine in African elephant (Loxodonta africana) and impala (Aepyceros melampus)

High performance liquid chromatography (HPLC) method development and validation for the determination of flunixin: Animal plasma based study

This study was designed to develop and validate a simple and efficient high performance liquid chromatography (HPLC) method to determine flunixin concentrations in Asian elephant’s (Elephas maximus) plasma. Flunixin was administered orally at a dose of 0.8 mg/kg, and blood samples were collected. Flunixin extraction was performed by adding an equal amount of acetonitrile to plasma and centrifuging at 4500 rpm for 25 minutes. The supernatant was removed, and flunixin was analyzed using HPLC-UV detection. Two methods were developed and tested utilizing two different mobile phases either with or without adding methanol (ACN: H2O vs. ACN: H2O: MeOH). Both methods showed excellent linearity and reproducibility. The limit of detection was 0.05 ug/ml and limit of quantification was 0.1 ug/ml. the efficiency of flunixin recovery was maximized by the addition of methanol to mobile phase (ACN: H2O: MeOH as 50:30:20) at 95% in comparison to 23% without methanol. In conclusion, adding methanol to HPLC methods for extraction of flunixin from elephants’ plasma yielded higher recovery rate than without methanol.

In vitro succinylcholine hydrolysis in plasma of the African elephant (Loxodonta africana) and impala (Aepyceros melampus)

In elephants the time lapsed from i.m. injection of an overdose of the muscle relaxant succinylcholine (SuCh) until death, is significantly longer than in impala. To determine a difference in the rate of SuCh hydrolysis, once the drug enters the circulation, contributes to this phenomenon we have measured the rate of hydrolysis of SuCh in elephant and impala plasma, and by elephant erythrocytes. Rate of hydrolysis was determined by incubating SuCh in plasma or erythrocyte lysate at 37 degrees C and quantifying the choline produced. Plasma SuCh hydrolytic activity in elephant plasma (12.1+/-1.7 Ul(-1) mean+/-S.D.; n=9) was significantly higher than it was in impala plasma (6.6+/-0.6 Ul(-1); n=5), but were approximately 12 and 21 times lower, respectively, than in human plasma. Elephant erythrocyte lysate had no SuCh hydrolytic activity. Applying this data to previous studies, we can show that the ratio of SuCh absorption to SuCh hydrolysis is expected to be 1.25:1 and 1.41:1 for elephants and impala respectively. It will thus take at least 1.7 times longer for elephant to achieve a plasma SuCh concentration similar to that in impala. We conclude that a more rapid hydrolysis of SuCh in elephant plasma is one factor that contributes to the longer time to death compared to impala.