Effect of injection site on alfaxalone‐induced sedation in ball pythons (Python regius)

Abstract

Administration of drugs that undergo hepatic metabolism or excretion should not be performed in the caudal third of the body in snakes, because it can result in significantly reduced drug efficacy. A hepatic first-pass effect is assumed to be the most likely underlying cause for the observed effect because part of the venous return from the caudal body flows directly to the liver.

Pharmacokinetics and pharmacodynamics of alfaxalone after a single intramuscular or intravascular injection in mallard ducks (Anas platyrhynchos)

“…The mallard ducks may not have been as sedated even with intravenous administration as authors hypothesized due to the renal portal system. However, the effect of the hepatic metabolism of blood passing through the renal portal system could be substantial and has been hypothesized to cause a difference in sedative effect in ball pythons ( Python regius ) from different administration routes (James et al, ; Yaw, Mans, Johnson, Doss, & Sladkey, ). Differences in plasma concentrations in birds are secondary to multiple contributing factors such as differences in metabolic rates between groups of birds and mammals, and the density of feather covering.…”

Pharmacokinetics of midazolam and its major metabolite 1‐hydroxymidazolam in the ball python (Python regius) after intracardiac and intramuscular administrations

“…A hepatic first-pass effect has been well reported in humans following the oral administration of midazolam (Nordt & Clark, 1997). Additionally, several anesthetic drugs undergoing hepatic metabolism have been reported to have a decreased C max or observable effect when administered in the caudal body of reptiles (Fink, Doss, Sladky, & Mans, 2018;Kummrow, Tseng, Hesse, & Court, 2008;Yaw, Mans, Johnson, Doss, & Sladky, 2018). Therefore, the reported bioavailability in ball pythons likely only applies to an IM injection in the cranial epaxial muscles.…”

A Critical Review on the Pharmacodynamics and Pharmacokinetics of Non-steroidal Anti-inflammatory Drugs and Opioid Drugs Used in Reptiles

“…Lastly, t 1/2 of tramadol was two-fold higher with hindlimb compared to forelimb administration in yellow-bellied slider turtles ( Giorgi et al., 2015b ) ( Table 9 ). This may be due to the possibility that injection sites may affect the pharmacokinetics of drugs, a point of consideration that has been highlighted and discussed in previous literature ( Holz et al., 1997a ; Kummrow et al., 2008 ; Yaw et al., 2018 ). Caudal blood from hindlimb administration drains mainly to the liver in turtles.…”