Influence of chloroquine and other substances on the collagenolytic activity in human osteoarthritic cartilage in vitro.

To investigate the influence of certain drugs and agents upon collagenolytic activity in human cartilage, homogenized articular cartilage from osteoarthritic human hips was incubated with dexamethasone, diclofenac, indometacin, phenazone, phenylbutazone, tiaprofenic acid, sulfasalazine, penicillamine, chloroquine, cysteine and a glycosaminoglycan-peptide complex (DAK-16). Collagenolytic activity was quantitated by the release of soluble hydroxyproline-containing peptides. The presence of collagenase in osteoarthritic cartilage was proved by the typical 75:25 cleavage products of type I collagen. Enzymatic collagen breakdown was found to be inhibited by chloroquine, cysteine, DAK-16, and sulfasalazine whereas the other tested agents had no significant effect. The inhibitory potency of chloroquine at therapeutical dose levels may be of pharmacological and therapeutic relevance.