Calcium channel blockers are often co-administered with digoxin because of a high frequency of hypertension and cardiac arrhythmia in patients undergoing hemodialysis. There have been several reports about the interactions between calcium channel blockers and digoxin mediated by P-glycoprotein in subjects with normal renal function, but few reports in patients undergoing hemodialysis. In this report, the interactions between digoxin and calcium channel blockers in patients undergoing hemodialysis were investigated. The serum digoxin concentration/digoxin dosage per week per body weight ratio (C/D ratio) was calculated, and the C/D ratio before and after co-administration of Ca channel blockers (verapamil, nifedipine, amlodipine) was compared. The rate of change in C/D ratio of digoxin was calculated, and the relationship between the rate of change in the C/D ratio of digoxin and the dose of Ca channel blocker per body weight was investigated. The C/D ratio of digoxin was significantly higher after co-administration of verapamil than that without verapamil (P<0.05), but there was no significant difference between co-administration of nifedipine or amlodipine and without co-administration. There was a significant correlation between the rate of change in the C/D ratio of digoxin before and after co-administration of verapamil and the dose of verapamil per body weight (r=0.909, P<0.001). It was suggested that the magnitude of the drug interaction between digoxin and verapamil was dependent on the verapamil dose per body weight.
Based on these results, when a high dose of verapamil is co-administered, it appears that adequate precautions are needed regarding digoxin intoxication even in patients undergoing hemodialysis.
抄録全体を表示