Effects of fluoroquinolones and glucocorticoids on cultivated tendon cells in vitro

Achilles tendon rupture is known to occur after administration of various drugs to patients. It is also reported to occur after treatment with fluoroquinolone and glucocorticoids. To study potential cytotoxic effects of fluoroquinolones (ciprofloxacin, pefloxacin, sparfloxacin) and triamcinolonacetonide on tendons an in vitro model of cultivated tendon cells (human, dog, mini-pig, rat, marmoset) was established. The cells were characterized by their morphological appearance and by the synthesis of proteoglycans and collagen type I. The cytotoxicity of the tested drugs was determined by measurement of mitochondrial dehydrogenase activity (MTT assay) and other parameters (viability, proteoglycan content, proliferation). These investigations revealed the following: (1) no marked differences were found between various species after ciprofloxacin treatment, only rat tendon cells reacted slightly less sensitively at the highest concentration (100 mug/ml); (2) no age-dependent effects of ciprofloxacin and triamcinolonacetonide were found in cultivated human tendon cells from patients of different ages; (3) the simultaneous administration of fluoroquinolones and triamcinolonacetonide resulted in a significantly greater reduction of cell viability than when they were administered alone. This could indicate that the combined administration of fluoroquinolones and glucocorticoids can favour the occurrence of tendon rupture.