Human whole blood assay for rapid and routine testing of non-steroidal anti-inflammatory drugs (NSAIDs) on cyclo-oxygenase-2 activity

Aim of this study was to present a simple, fast and reliable method to examine the capacity of NSAIDs to inhibiting COX-2 activity that uses rapid (stimulation takes only 5 h compared to other existing protocols) and routine testing. The assay includes elimination of COX-1-activity using ASS (a selective COX-1 inhibitor) and the thromboxane synthetase inhibitor (TXBSI), COX-2 induction via LPS and measurement of PGE(2). Using TXBSI reduces the amount of LPS and results in higher prostaglandin production. Cremophor EL-EtOH was used as vehicle instead of DMSO because within a defined concentration range, Cremophor EL-EtOH allows even very hydrophobic drugs to be solubilized and applied in vitro without cell damage. Cremophor EL-EtOH at 0.2% was optimal as at this relatively low concentration excellent drug dissolution was obtained whereas many hydrophobic substances precipitate in 0.2% DMSO. Our results demonstrate that the IC(50) values for the tested NSAIDs are in the range of published data.