Researchers at Kansas State University and Iowa State University have collaborated to study the pharmacokinetics of the analgesic, flunixin meglumine, administered to mature pigs by the intravenous (IV), intramuscular (IM) and oral (PO) routes.

The team, led by first-named author of the paper in BMC Veterinary Research, Monique D Pairis-Garcia, based in Ames, explained that appropriate pain management for lameness in swine is a critical control point for veterinarians and producers but there is a lack of science-based guidance on optimal housing, management and treatment of lameness.

In their study, six mature swine (121–168kg) were administered an IV, IM or PO dose of flunixin meglumine at a target dose of 2.2mg per kg in a cross-over design with a 10-day wash-out period between treatments.

Plasma samples collected up to 48 hours post-administration were analysed by high pressure liquid chromatography and mass spectrometry (HPLC-MS) followed by non-compartmental pharmacokinetic analysis.

No adverse effects were observed with flunixin meglumine administration for all routes.

Flunixin meglumine was administered at an actual mean dose of 2.21mg per kg (range: 2.05-2.48mg per kg) IV, IM and PO.

A mean peak plasma concentration (C-max) for IM and PO administration was 3,748ng per ml (range: 2,749–6,004ng per ml) and 946ng per ml (range: 554–1,593ng per ml), respectively.

T-MAX was recorded at 1.00 hour (range: 0.50-2.00 hours) and 0.61 hours (range: 0.17-2.00 hours) after PO and IM administration. Half-life (T-½ λz) for IV, IM and PO administration was 6.29 hours (range: 4.84-8.34 hours), 7.49 hours (range: 5.55-12.98 hours) and 7.08 hours (range: 5.29-9.15 hours) respectively.

Bioavailability for PO administration was 22 per cent (range: 11-44 per cent) compared to IM at 76 per cent (range: 54-92 per cent).

The researchers conclude from their results that PO administration of flunixin meglumine is not the most effective route for mature swine when compared to IV and IM.

Pairis-Garcia and co-authors explain that, compared to IM administration, lower bioavailability and C-max of the PO route suggest that the latter route is less likely to be an effective therapy.

Reference

^{Pairis-Garcia M.D., L.A. Karriker, A.K. Johnson, B. Kukanich, L. Wulf, S. Sander, S.T. Millman, K.J. Stalder and J.F. Coetzee. 2013. Pharmacokinetics of flunixin meglumine in mature swine after intravenous, intramuscular and oral administration. BMC Veterinary Research. 9:165. doi:10.1186/1746-6148-9-165}

August 2013