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In vitro investigation on the impact of the surface‐active excipients Cremophor EL, Tween 80 and Solutol HS 15 on the metabolism of midazolam
Author(s) -
Bravo González Roberto C.,
Huwyler Jörg,
Boess Franziska,
Walter Isabelle,
Bittner Beate
Publication year - 2004
Publication title -
biopharmaceutics and drug disposition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 58
eISSN - 1099-081X
pISSN - 0142-2782
DOI - 10.1002/bdd.383
Subject(s) - pulmonary surfactant , chemistry , phosphatidylcholine , liposome , hepatocyte , membrane , chromatography , glucuronidation , microsome , cytotoxicity , in vitro , biochemistry , phospholipid
Abstract The impact of the surface‐active formulation ingredients Cremophor EL, Tween 80 and Solutol HS 15 on the intrinsic clearance ( Cl int ) of midazolam (MDZ) was investigated in rat hepatocytes and microsomes. In rat hepatocytes with 0.003%, 0.03% and 0.3% (w/v) Solutol HS 15 already present in the incubation medium, the Cl int was significantly reduced in a dose‐dependent manner by about 25%, 30% and 50%, respectively. In the presence of Cremophor EL and Tween 80 a significant reduction in Cl int by about 30% and 25%, respectively, was observed at 0.03% surfactant concentration. At 0.3% of Cremophor EL and Tween 80, Cl int was reduced by about 50% and 20%, respectively. A reduction in Cl int was also observed in experiments with rat liver microsomes. At surfactant concentrations up to 0.03%, cytotoxicity assays (lactate dehydrogenase release, adenosine triphosphate content) as well as light microscope investigations did not reveal any cytotoxic impact of the surfactants on the hepatocyte monolayer. A potential interaction of the surfactants with biological membranes was determined using phosphatidylcholine‐cholesterol liposomes loaded with self‐quenching concentrations of carboxyfluorescein. No marked release of carboxyfluorescein from the liposomes (that would be an indication for a surfactant‐dependent disruption of membrane integrity) was observed up to concentrations of 0.03% of the different surfactants. It is concluded that cytochrome P450 3A mediated metabolism of MDZ seems to be prevented by all surfactants at concentrations above 0.03%. In our experiments the surfactants did not show toxic effects at concentrations that resulted in a decreased Cl int of MDZ. Thus, a direct inhibition of the metabolizing enzymes, a molecular interaction with the microsomes as well as an alteration of membrane properties that did not yet result in a release of LDH have to be taken into consideration as reasons for the observed changes in the metabolism of MDZ. Copyright © 2004 John Wiley & Sons, Ltd.