Therapeutic Drug Monitorings

Therapeutic drug monitoring (TDM) consists of measurement of plasma or serum concentrations of drug for therapeutic and safety purposes. There are two purposes for TDM: ensuring therapeutic concentrations consistent with efficacy, and ensuring safety, particularly for those drugs with a narrow therapeutic index. The most common drugs for which TDM is performed in horses are the aminoglycosides. TDM should be performed at steady state in most instances. Steady state concentrations occur after 4-5 half-lives of the specific drug. The results obtained from TDM analysis will be presented as serum or plasma concentrations of drug. Each of the drugs has specific targets for TDM. Some of these targets are based on data from horses, whereas many are extrapolated from human and small animal pharmacology. As such, they must be interpreted with caution and in light of clinical and clinicopathological findings.