Effect of cyclophosphamide and its analogs on collagen arthritis in rats.

The effects of cyclophosphamide (CY) and its structurally related analogs, ifosfamide (Ifo), sufosfamide (Sufo), and mafosfamide (Mafo), on collagen arthritis in Sprague-Dawley rats were examined. Prophylactic treatment with 7.5-10 mg/kg/day of CY. 15 mg/kg/day of Ifo, and 10-15 mg/kg/day of Sufo for the first 10 days starting on the same day as the type II collagen immunization suppressed arthritis induction as well as humoral immune response to type II collagen. Prophylactic treatment with Mafo at doses ranging from 10 to 40 mg/kg/day for 10 days was ineffective in suppressing the disease development. When drug treatment was started only during the immediate preclinical phase of arthritis, the development of arthritis was suppressed in the animals treated with 10 mg/kg/day of CY and 15 mg/kg/day of Ifo from Day 5 to Day 14. Additional studies demonstrated that treatment with 10 mg/kg/day of CY and 15 mg/kg/day of Ifo started at the time of disease onset significantly suppressed the severity of arthritis compared with the control group. These results show the effectiveness of Ifo and CY on this animal model of polyarthritis and suggest the possibility of clinical use of Ifo for the treatment of human arthritides similar to CY.