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Sammanfattning

Objective To measure the bioavailability, maximal plasma concentration (C-max) and half-life (t(1/2)) of fentanyl in rabbits after intravenous (IV) and subcutaneous (SC) administration. Secondary aims were to investigate behavioural effects and faeces production. Study design Randomized, experimental, crossover study. Animals A group of six male New Zealand White rabbits, Crl:KBL(NZW), aged 5-6 months and weighing 2.9-3.7 kg. Methods Fentanyl 15 mu g kg(-1) was administered IV and SC to rabbits with a 14 day washout period. Plasma was sampled at 2 (IV), 5, 10, 15, 30, 60, 90, 120 (IV + SC), 300 (SC) and 390 (SC) minutes and analysed by liquid chromatography-mass spectrometry. Sedation was scored from 0-3, 3 being most sedated, 10 and 45 minutes after administration by an assessor blinded to treatment. Oxygen was supplemented if the haemoglobin oxygen saturation (SpO(2)) was <90%. After the experiment, faeces and urine were weighed. Data are presented as mean +/- standard deviation or median (range). Results Bioavailability for fentanyl after SC administration was 47% +/- 16% and 50% (27%-68%). The t(<1/2>) for fentanyl after IV and SC administration was 65 +/- 11 and 275 +/- 16 minutes, respectively. The C-max of fentanyl after SC injection was 0.55 +/- 0.17 ng mL(-1) and the time to maximal concentration (T-max) was 15 (15-68) minutes. Median sedation score at 10 minutes was higher (p = 0.014) after IV than after SC administration (3 and 1, respectively). After IV administration, but not SC administration, 5/6 rabbits became recumbent and 2/6 rabbits required oxygen. There was no statistically significant difference in faecal/urinary output between groups. Conclusions and clinical relevance Fentanyl administered SC as the sole drug to conscious rabbits resulted in variable plasma concentrations substantially lower than after IV administration. Supplemental oxygen should be available whenever fentanyl is administered.

Nyckelord

analgesia; bioavailability; plasma concentrations; veterinary anaesthesia

Publicerad i

Veterinary Anaesthesia and Analgesia
2026, volym: 53, nummer: 1, artikelnummer: 101159

SLU författare

UKÄ forskningsämne

Klinisk vetenskap

Publikationens identifierare

  • DOI: https://doi.org/10.1016/j.vaa.2025.11.003

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/145608