Elimination kinetics of Lipofundin MCT: bolus injection and infusion compared

Fifteen healthy young probands (nine males, six females) underwent an intravenous fat tolerance test (IVFTT) and, on the following day, a fat infusion lasting 6 hr. The emulsion tested was Lipofundin MCT 10%. One half of its triglyceride mass contains medium chain fatty acids. The IVFTT was started by injection of 0.1 g lipid per kg body weight into the fasting proband. Lipid elimination was estimated by measurement of light-scattering intensity of serum samples collected during a 60-min period. Individual fraction elimination rate constants covered a considerable range (K2 = 8.84 +/- 3.45%/min). The infusion test was performed at a rate of 0.1 g lipid per kg body weight and hr and lasted 6 hr. Serum triglyceride concentrations were determined enzymatically. They increased from 0.941 +/- 0.285 mmol/liter at the fasting state to a plateau level of 1.753 +/- 0.306 mmol/liter during infusion, and returned to initial levels 1 to 2 hr after the infusion was terminated. Individual triglyceride increments during infusion were significantly correlated with half-life periods of lipid elimination during IVFTT (r = 0.792, p less than 0.001). This relationship was derived using a model of the stationary state during infusion. We conclude that elimination kinetics of exogenous fat given either as bolus or infusion are ruled by the same fractional elimination rate constant K2. The IVFTT provides an estimate of the stationary triglyceride increment during a lipid infusion lasting several hr.