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Research article - Peer-reviewed, 2020

Bioavailability of subcutaneous and intramuscular administrated buprenorphine in New Zealand White rabbits

Askar, Raad; Fredriksson, Elin; Manell, Elin; Hedeland, Mikael; Bondesson, Ulf; Bate, Simon; Olsen, Lena; Hedenqvist, Patricia


Background Buprenorphine is one of the most used analgesics for postoperative pain in rabbits. The recommended dose in rabbits (0.01-0.05mg/kg) is the same for intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration, despite lack of pharmacokinetic data. Five male and five female New Zealand White rabbits (meanSD body weight 3.10.3kg) were administered 0.05mg/kg buprenorphine by the IV, IM and SC routes and 0.1mg/kg by the SC route, in a cross-over design with two-week wash-out periods between treatments. Blood was collected before, and up to 8h post buprenorphine injection, for determination of serum levels by UPHLC-MS/MS.Results The area under the time concentration curve (AUC(0-t)) was lower after SC (398 +/- 155ng/mL/min) than IM (696 +/- 168ng/mL/min, p < 0.001) and IV (789 +/- 189ng/mL/min, p < 0.001) administration. The maximum serum concentration was lower after SC (2.2 +/- 1.4ng/mL) than after IM (11 +/- 3.2ng/mL) administration (p < 0.001). The bioavailability was lower after SC (50 +/- 19%) than after IM (95 +/- 21%) administration (p=0.006). The elimination half-life was longer after SC (260 +/- 120min) than after IM (148 +/- 26min, p=0.002) as well as IV (139 +/- 33min) injection (p < 0.001). An increase in the SC dose from 0.05 to 0.1mg/kg resulted in an increase in the area under the time concentration curve of 50% in female (p=0.022) and 165% in male rabbits (p < 0.001). The bioavailability did not change in the females (36 +/- 14%, p=0.6), whereas it increased in the males (71 +/- 23%, p=0.008).Conclusions The lower bioavailability of 0.05mg/kg buprenorphine after SC administration could explain the lack of efficacy seen in clinical pain studies in rabbits, using this route. For immediate pain relief, IV or IM administration is therefore be recommended, whereas SC administration may be useful to sustain analgesic serum levels, once efficient pain relief has been achieved. The current data do not support an increase in dose to compensate for the lower SC bioavailability.


NZW rabbit; Buprenorphine bioavailability; Administration routes; Opioid pharmacokinetics

Published in

BMC Veterinary Research
2020, volume: 16, number: 1, article number: 436
Publisher: BMC

Authors' information

Askar, Raad
Stockholm University
Fredriksson, Elin
No organisation
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Hedeland, Mikael
Uppsala University
Bondesson, Ulf
Uppsala University
Bate, Simon
Swedish University of Agricultural Sciences, Department of Clinical Sciences
Swedish University of Agricultural Sciences, Department of Clinical Sciences

UKÄ Subject classification

Clinical Science

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