Effect of contrast media on the enzyme activity of condoliase: In vitro assessment

BACKGROUND: Condoliase has been used in Japan to treat patients with lumbar disc herniation by its injection into the nucleus pulposus. The injection of condoliase together with contrast media is prohibited; because there are no data whether contrast media have any effect on condoliase activity. This study aimed to elucidate the effects of contrast media on condoliase activity. METHODS: Condoliase with chondroitin sulfate (CS) and without CS were mixed with various contrast media (nonionic [iohexol or iotrolan]; ionic [amidotrizoic acid]). (i) The mixtures with CS were incubated at 37°C; (ii) the mixtures without CS were stored at 24°C for 60 min, followed by addition of CS to assess condoliase activity by measuring the amount of N‐acetylhexosamines enzymatically cleaved from CS using Morgan–Elson method. RESULTS: (i) In the presence of CS, the ionic contrast media reduced condoliase activity within 10 min in a dose‐dependent manner, and the nonionic contrast media had no effect on condoliase activity for at least 120 min. (ii) In the absence of CS, the ionic contrast media almost completely inactivated condoliase within 15 min, and the nonionic contrast media also reduced condoliase activity; the residual activity was 65% with iotrolan and 35% with iohexol at 60 min. CONCLUSIONS: The ionic contrast media significantly reduced condoliase activity regardless of presence or absence of CS. Although the nonionic contrast media did not affect condoliase activity in the presence of CS, it reduced activity in the absence of CS. Mixing condoliase with contrast media, especially ionic type contrast media, should be avoided.