The effects of colchicine and hydroxychloroquine on the cyclo-oxygenases COX-1 and COX-2

The aim of this study was to test whether colchicine and hydroxychloroquine have an inhibitory effect on cyclo-oxygenases (COX). Methods: Measurement of COX-1 and COX-2 activity was performed by using whole blood assay. Serum thromboxane (TXA) and plasma prostaglandin 2 (PGE2) levels were determined using a commercially available enzyme immunoassay kit. Celecoxib, etodolac, and nimesulide were also tested as controls. Since the study was intended to find a qualitative effect rather than a quantitative relationship between the drugs and the enzymes, we used higher concentrations than the therapeutic range. Results: Colchicine did not have an inhibitory effect on cyclo-oxygenases. Hydroxychloroquine had a mild inhibitory effect in a relatively high concentration. As expected, celecoxib, etodolac, and nimesulide did have an inhibitory effect on the cyclo-oxygenases.Conclusions: Neither colchicine nor hydroxychloroquine exert their anti-inhibitory effect through inhibition of cyclo-oxygenases.