[Infusion kinetics of drugs injected into the drip chamber of an infusion set].

The infusion kinetics of drugs injected into the "drip-chamber" of an i.v. infusion set has never been studied, although this route of drug administration is used more and more frequently in hospitalized patients. The drug is eliminated from this "drip-chamber" and hence infused into the body by 1.-order kinetics. A half-life of administration can be calculated and experimentally verified. This t 1/2 is equal to the ratio of the volume of infusion fluid in the "drip-chamber" (which can be estimated) and the infusion velocity of the i.v. drip (which is chosen) with the ln 2 as the proportionality constant. Hence the velocity of administration of the drug is not constant. Just after the injection more of the drug reaches the body per unit time than later on. This type of drug administration should therefore not be used if high plasma concentrations at the beginning are to be avoided or a constant infusion is desired.