Constant rate infusions for analgesia: A review of the options

摘要

Provision of adequate analgesia is important in horses undergoing surgery or suffering from painful conditions. Horses undergoing invasive surgery or suffering from severe pain may benefit from a constant rate infusion (CRI) of an analgesic. The advantages of a CRI are that it can provide predictable plasma concentrations of the drug at steady state conditions, avoiding the variations that occur with intermittent bolus dosing and thus the more consistent analgesia can reduce the likelihood of 'breakthrough' pain. Knowledge of the pharmacokinetics is required to calculate infusion rates for individual drugs although it should be appreciated that many of the studies performed include healthy horses receiving only the drug being evaluated. Thus, monitoring the effects of the drugs and adjusting the rates as required is important when using CRIs in clinical cases as abnormalities in body composition, organ function and concurrent drug administration may alter the pharmacokinetics of the drug.