Pharmacokinetics of a Long-Acting Formulation of Oxytetracycline in Freshwater Crocodiles (Crocodylus siamensis) after Intramuscular Administration at Three Different Dosages

Abstract

To date, the necessary pharmacokinetic information has been limited to establish suitable therapeutic plans for freshwater crocodiles. Therefore, this study was conducted to evaluate the pharmacokinetic profile of the oxytetracycline long-acting formulation (OTC-LA) in the freshwater crocodile, Crocodylus siamensis, following a single intramuscular (i.m.) administration at three different dosages of 5, 10 and 20 mg/kg body weight (b.w.). Blood samples were collected at assigned times up to 216 h after i.m. administration at the three different dosages. The plasma concentrations of OTC were measured using a validated liquid chromatography tandem-mass spectrometry (LC-MS/MS) method. The Cmax (± SD) values of OTC were 2.15 ± 0.51 µg/mL, 7.68 ± 1.08 µg/mL and 17.08 ± 2.09 µg/mL at doses of 5, 10 and 20 mg/kg b.w., respectively. The elimination half-life values were 33.59 ± 2.51 h, 38.42 ± 5.47 h and 38.04 ± 1.98 h at dosages of 5, 10 and 20 mg/kg b.w., respectively. Based on the pharmacokinetic data, the pharmacokinetic/pharmacodynamic (PK/PD) index, the susceptibility break-point and plasma protein binding, a dosage once every two weeks of 10 mg/kg b.w. OTC intramuscularly might be suitable for initiating the treatment of susceptible bacterial infections in freshwater crocodiles. However, further PK/PD studies are warranted to confirm whether the dose rates used in this study can produce longer-term antimicrobial success for diseases caused by susceptible bacteria in freshwater crocodiles.

Pharmacokinetic characteristics of azithromycin in freshwater crocodiles (Crocodylus siamensis) after intramuscular administration at three different dosages

“…The pharmacokinetic characteristics of some antimicrobial drugs such as enrofloxacin, tetracycline have been investigated in American alligators (Helmick et al, 2004; Rivera et al, 2012) while enrofloxacin has been investigated in estuarine crocodiles (Martelli et al, 2009). On the contrary, pharmacokinetic profiles of marbofloxacin, enrofloxacin, ceftriaxone, amoxicillin, oxytetracycline, and clarithromycin have been determined infreshwater crocodiles (Poapolathep et al, 2017; Poapolathep et al, 2022; Poapolathep, Giorgi, Chaiyabutr, Chokecharoenrat, et al, 2020; Poapolathep, Giorgi, Chaiyabutr, Klangkaew, et al, 2020; Poapolathep, Giorgi, Klangkaew, Phaochoosak, et al, 2020; Poapolathep, Klangkaew, Phaochoosak, Wongwaipirote, et al, 2020); however, there are no reports on the pharmacokinetics of AZM in freshwater crocodiles.…”

Comparative effectiveness of interventions for treating interdigital necrobacillosis in cattle: A network meta-analysis

“…Ceftiofur and oxytetracycline belong to the drugs with time-dependent kinetics (Nie et al 2016;Poapolathep et al 2020), whereas different killing patterns have been described for tulathromycin, depending on the target pathogen (Zhou et al 2017a;Zhou et al 2017b). On top of that, this semi-synthetic macrolide is not applicable to female dairy cattle 20 months of age and beyond (Van Metre 2017).…”

Veterinary pharmacology: A world almost unexplored with huge potential

“…Thus, the support of independent scientists results of paramount importance in order to expand the knowledges even in niche areas of the veterinary field. Recent examples of that have been reported in geese ( Sartini et al., 2020a , 2020 b , 2021a ,2021 b , 2021 c , 2022b ) and crocodiles ( Poapolatep et al., 2017 ; 2020a ,2020 b , 2020 c , 2020 d , 2022a , 2022b) both considered minor species at global level. A long series of drugs have been tested by independent scientists introducing new important data in animals that have been ignored so far.…”