OBJECTIVE To assess pharmacokinetics and correlation of pharmacokinetics and pharmacodynamics of simendan, a new calcium-sensitizing compound aimed at the treatment of congestive heart failure, in healthy volunteers. METHODS Simendan was administered to eight healthy subjects in seven different doses, and its concentrations in plasma and proportions of enantiomers (levosimendan and dextrosimendan) were determined. Hemodynamic effects were measured by M-mode echocardiography. RESULTS The area under the plasma concentration time-curve increased linearly and correlated with dose (p < 0.001). The volumes of distribution were small (mean VC, 8.5 to 14.1 L; VSS, 12.8 to 28.4 L) and elimination fairly fast (mean t1/2 beta, 0.83 to 1.77 hours). There were only minor differences between the pharmacokinetic profiles of the enantiomers of simendan. The increase in maximal ejection fraction (EF) correlated significantly with the plasma concentrations of simendan (p < 0.01; r2 = 0.33). However, the correlation coefficient was higher between estimated concentrations of simendan in peripheral compartment and ejection fraction; r2 was 0.79 (p < 0.01) and 0.94 (p < 0.001) after 2 and 5 mg doses, respectively. One subject after 5 mg simendan and one subject after 10 mg simendan had transient vasovagal reactions consisting of decreases in heart rate and blood pressure. CONCLUSIONS Simendan has favorable and predictable hemodynamic actions. The pharmacokinetic profile facilitates rapid dose adjustments during intravenous administration.