Treatment of radiation nephropathy with captopril.

Both experimental and clinical radiation nephropathy are typically progressive, evolving to kidney failure over weeks to months. Other late radiation injuries (spinal cord, lung) are also progressive and have no known specific antidote. Recent reports of the efficacy of captopril in modifying radiation injury of the lung prompted this trial of captopril in treating established radiation nephropathy. Six months after 15-27 Gy in 12 fractions bilateral renal irradiation, 72 rats with blood urea nitrogen > 4.1 mmol/liter were started on captopril (500 mg/liter) or no drug in the drinking water. Subsequent survival was significantly enhanced in rats receiving captopril as opposed to no drug (P = 0.0013), and the rate of rise of blood urea nitrogen was significantly diminished (P < 0.0001) in the animals on captopril. Urine protein excretion was also reduced from initially elevated levels in the rats on captopril compared to levels in rats given no drug. We conclude that captopril therapy preserves kidney function, reduces proteinuria, and enhances survival in experimental radiation nephropathy.