Principles of intravenous drug infusion

It is possible to establish and maintain targeted blood and effect-site drug concentrations with reasonable accuracy using a ‘bolus, elimination, transfer’ (BET) infusion regimen. Simulation software that employs pharmacokinetic models can be used to drive infusion pumps or to design manually-controlled BET infusions. Prolonged infusions can result in prolonged recovery times. However the elimination half-lives of infused lipid soluble drugs have little or no relevance to rates of recovery because elimination half-life does not take redistribution from peripheral compartments into account. A better method is to calculate the context-sensitive decrement times (context-sensitive referring to the infusion duration). These are not represented by a single number: they are a continuum of time values that are a function of infusion duration and can be represented by a graph. Considering that decrement times depend on the concentrations achieved as well as the dose history, it is often difficult for clinicians to anticipate a patient's time to recovery. Pharmacokinetic simulation software continuously calculates and displays expected recovery times, helping clinicians to ascertain when to reduce or terminate the infusion.