Mannitol potentiates cyclosporine nephrotoxicity

A possible drug interaction between cyclosporine (CyA) and mannitol was tested for in female Wistar rats infused continuously with CyA 10 mg (40-50 mg/kg BW) in 24 ml mannitol 20% daily for 3 to 4 days (group CIM). For comparison, two other groups of rats were infused either with the same amount of CyA in 24 ml NaCl 0.9% (group CINa) or with the same amount of mannitol without CyA (group M). No animal of groups CINa or M, but 6 out of 10 group CIM rats developed severe oligo-anuric acute renal failure (ARF). Histologically massive vacuolisation of proximal tubular epithelia was found in the kidneys of CIM rats with ARF, while CIM rats without ARF showed minor to moderate degrees of vacuolisation. No vacuolisation was seen in groups CINa and M. Moderate amounts of tubular inclusion bodies and microcalcifications were detected in the kidneys of CIM rats without ARF and in those of CINa rats. To elucidate the mechanism of ARF, renal blood flow, creatinine clearance and proximal tubular pressures were measured in the kidneys of another series of CIM rats infused for 48-96 hours with CyA and mannitol. Renal blood flow and proximal tubular pressures in the kidneys of animals that had not or not yet developed ARF did not differ from those in rats infused with mannitol alone despite histological alterations with minor to moderate degrees of vacuolisation.(ABSTRACT TRUNCATED AT 250 WORDS)