Compounding iron dextran with meloxicam or flunixin meglumine for use in piglets at time of processing

Research has documented that non-steroidal anti-inflammatory drugs (NSAIDs) reduce pain and pain related behaviors in piglets. The use of analgesics at the time of piglet processing increases the amount of piglet handling and injections as well as increases the labor for the producer. The ability to give an injection of an NSAID at the same time as an iron product (compounded) would help minimize animal handling and labor. The objective of this study was to determine if the compounding of iron dextran (Ferroforte® 200 mg/mL) and the NSAID meloxicam (Metacam® Injectable Solution 20 mg/mL) or flunixin meglumine (Banamine® Sterile Solution Injectable 50 mg/mL) would reduce the amount of (NSAID and/or iron dextran) available to the piglet.

Part 1: Sixty piglets were selected at 2d of age and were assigned to 1 of 3 treatment groups: Iron dextran (ID), compounded ID and meloxicam, or compounded ID and flunixin meglumine. Prior to treatment a whole blood sample was taken at 3d of age to determine the baseline hemoglobin status of each piglet. A second blood sample was taken at 21d of age (just prior to weaning). Hemoglobin (Hgb) concentrations were analyzed in at the Animal Health Laboratory (AHL), University of Guelph. Mixed linear regression was used to examine the effect of treatment on Hgb levels just prior to weaning.

Part 2: Forty piglets were selected at 3-4d of age and were assigned to receive 1 of 5 treatments: ID alone, compounded ID and meloxicam, compounded ID and flunixin meglumine, meloxicam alone, and flunixin meglumine alone, given intramuscularly. Blood samples were taken at regular intervals over 72 hours via pre-placed jugular catheters. Plasma was analyzed using mass spectrometry methods to determine NSAID levels. Pharmacokinetic parameters for plasma meloxicam and flunixin meglumine concentration-time profiles were determined for each animal using noncompartmental pharmacokinetic analysis approaches.

No significant effect of compounding either NSAID with ID on measured blood Hgb levels was found. Significantly reduced concentrations of both NSAIDs (Cmax and AUC) were found when compounded with ID compared to the levels noted when either NSAID was given alone.

The compounding of meloxicam or flunixin meglumine with ID produces a likely drug interaction, which does not appear to affect the ability of ID to maintain adequate Hgb concentrations, but does reduce the bioavailability of the NSAID for absorption into the systemic circulation. The clinical ramifications of these findings require additional efficacy studies to evaluate whether adequate analgesia is being provided at the current NSAID concentrations in the compounded formulation.

Disclosure of Interest: None Declared.