Background: The dose of milrinone should be reduced in patients with renal failure. However, there is little data examining the relationship between plasma concentration of milrinone (pCmil) and renal function in intravenous infusion.
Methods: We evaluated the pCmil relative to renal function during intravenous infusion. We enrolled 10 heart failure patients. Milrinone was continuously infused at a rate of 0.2 μg/kg/min. Blood samples were collected at 6, 12, 24, and 48 h after the beginning of infusion. Urine was sampled during the first 24 h to calculate creatinine clearance (CLcr) and renal clearance of milrinone (rCLmil).
Results: The pCmil exhibited stability over 6 h after the beginning of infusion. During the first 24 h, CLcr and rCLmil were 62.2±30.6 ml/min and 1.67±0.77 ml/kg/min (106.2±60.3 ml/min), respectively. The rCLmil was highly correlated with CLcr. Y=1.77X−3.89 (X, CLcr; Y, rCLmil; R2=0.809, P<0.0001). Significant correlations were observed between CLcr and the plasma concentration during the continuous infusion. This correlation was expressed as the equation Y=51.1 × (BW/X)+28.2 (X; CLcr, Y; plasma concentration; BW, body weight; R2=0.695, P<0.01).
Conclusion: The pCmil exhibited stability 6 h or later after the continuous infusion of milrinone 0.2 μg/kg/min. The pCmil can be estimated by the value of CLcr and BW.