Intravenous infusion conditions. Implications for pharmacokinetic monitoring.

Drugs are often given intravenously with an expectation that the predicted serum concentrations will be achieved rapidly. Routine pharmacokinetic monitoring of some drugs may be of limited value, unless the effect of intravenous drug delivery systems on serum concentrations is known. In vitro studies have demonstrated that the actual time for complete drug delivery can be markedly longer than predicted and is dependent inter alia on factors including the delivery device, flow rate, injection site, drug volume and tubing diameter. Studies in paediatric patients have shown that the serum concentrations of drugs, including aminoglycosides and chloramphenicol, are strongly influenced by intravenous drug delivery systems. Similarly, data from adult patients have indicated that a drug delivery system can affect serum concentrations of aminoglycosides. Some data are available about the pharmacokinetics of drugs delivered by newer devices, e.g. controlled release infusion systems, membrane devices and implanted pumps, but additional research is needed to determine their predictability of delivery and pharmacokinetics of commonly used drugs. To achieve optimal therapeutic outcomes in patients, it is crucial to understand the impact of an intravenous drug delivery system on serum concentrations and to develop guidelines for pharmacokinetic monitoring.