Synergistic effect of ofloxacin and magnesium deficiency on joint cartilage in immature rats

Lozo E, Riecke K, Schwabe R, et al. · Antimicrobial Agents and Chemotherapy

Ofloxacin alone at 30 mg/kg twice daily caused no cartilage lesions on a standard diet (0 of 12 at 7 days), but produced lesions in 10 of 12 magnesium-deficient rats (p < 0.01); the deficient diet alone lesioned 1 of 6, and 100 mg/kg twice daily lesioned 2 of 5 even on a standard diet. Plasma magnesium was 0.27 against 0.88 mmol/L on the deficient diet, peak plasma ofloxacin about 10 mg/L (the range of high-dose human therapy) and cartilage concentrations two to three times plasma — quinolone chondrotoxicity depends heavily on functional magnesium status.

Population

4-week-old Wistar rats on standard vs magnesium-deficient diets, 5-12 per group

Intervention

Ofloxacin 30 mg/kg twice daily for 7 days

Comparator

Same dose on magnesium-replete diet

Limitations

Juvenile rodent model; magnesium deficiency was experimentally induced to a degree the authors say patients rarely reach; human dietary relevance speculative. Funded by the Deutsche Forschungsgemeinschaft; one author affiliated with Protina GmbH, which markets magnesium preparations.