Influence of fosfomycin and tobramycin on vancomycin-induced nephrotoxicity

Since combinations of fosfomycin and vancomycin or tobramycin and vancomycin could be of advantage in the therapy of staphylococcal infections, we studied renal tolerance of both combinations. The experimental animal was the rat and the parameters of nephrotoxicity were cyturia and enzymuria. The experiments showed that fosfomycin at dosages of 50 and 250 mg/kg protected against nephrotoxicity caused by vancomycin (dose: 50 mg/kg), whereas the administration of both tobramycin (dose: 2.5 mg/kg) and vancomycin (dose: 50 mg/kg) resulted in an increase of cyturia and enzymuria. However, repeated dosing of vancomycin (single dose: 50 mg/kg) led to renal accumulation when combined with fosfomycin (single dose: 250 mg/kg); renal vancomycin concentrations were lower. This study suggests similarities in the renal handling of vancomycin and aminoglycosides and demonstrates the possibility of reducing drug-associated nephrotoxicity.