Pharmacokinetics of morphine in combination with dexmedetomidine and maropitant following intramuscular injection in dogs anaesthetized with halothane |
| |
| Authors: | Sandeep Raj Karna Preet Singh Paul Chambers Kavitha Kongara |
| |
| Institution: | School of Veterinary Science, Massey University, Palmerston North, New Zealand |
| |
| Abstract: | The purpose of this study was to evaluate the pharmacokinetics of morphine in combination with dexmedetomidine and maropitant injected intramuscularly in dogs under general anaesthesia. Eight healthy dogs weighing 25.76 ± 3.16 kg and 3.87 ± 1.64 years of age were used in a crossover study. Dogs were randomly allocated to four groups: (1) morphine 0.6 mg/kg; (2) morphine 0.3 mg/kg + dexmedetomidine 5 μg/kg; (3) morphine 0.3 mg/kg + maropitant 1 mg/kg; (4) morphine 0.2 mg/kg + dexmedetomidine 3 μg/kg + maropitant 0.7 mg/kg. Blood samples were collected before, 15 and 30 min, and 1, 2, 3 4, 6 and 8 hr after injection of the test drugs. Plasma concentration of the drugs was determined by liquid chromatography-mass spectrometry. The elimination half-life (T1/2) of morphine was higher and the clearance rate (CL) was lower when combined with dexmedetomidine (T1/2 = 77.72 ± 20.27 min, CL = 119.41 ± 23.34 ml kg?1 min?1) compared to maropitant (T1/2 = 52.73 min ± 13.823 ml kg?1 min?1, CL = 178.57 ± 70.55) or morphine alone at higher doses (T1/2 = 50.53 ± 12.55 min, CL = 187.24 ± 34.45 ml kg?1 min?1). Combining morphine with dexmedetomidine may increase the dosing interval of morphine and may have a clinical advantage. |
| |
| Keywords: | alpha-2-adrenoceptor agonist dogs halothane intramuscular neurokinin-1 receptor antagonist opioid |
|
|
