Abstract
A precise evaluation of renal function is necessary for the accurate therapeutic drug monitoring of digoxin,a drug that is eliminated via the urine.However,the evaluation of renal function in muscular dystrophy patients tends to be problematic because muscular dystrophy is a muscle-wasting disorder which leads to a decrease in serum creatinine.In this study,we examined whether cystatin C would be more effective as an index than serum creatinine in the therapeutic drug monitoring of digoxin in 14 muscular dystrophy patients whose renal function was normal or slightly impaired.
The serum concentration of digoxin was more closely correlated with reciprocal cystatin C levels (r=0.526)than reciprocal creatinine levels (r=0.435).Furthermore,when simulation serum concentrations of digoxin were calculated from the GFR obtained with Larsson’s formula and Grubb’s formula 2,which use cystatin C,there was a close correlation between simulation and measured serum concentrations of digoxin (Larsson’s formula ; r=0.694,Grubb’s formula 2 ; r=0.723).
However,the simulation concentrations of serum digoxin were about half the measured concentrations (Larsson's formula ; y=0.602 x-0.056,Grubb’s formula 2 ; y=0.499 x-0.162)
Our results indicated that cystatin C is a useful index for the therapeutic drug monitoring of digoxin in muscular dystrophy patients.Further,it would be possible to design the administration of digoxin for muscular dystrophy patients by substituting simulation digoxin concentrations in correlation formulas that we created.
