Relationship between the pharmacokinetics of levosimendan and its effects on cardiovascular system

Levosimendan, a Ca(2+) sensitizer, has emerged as an alternative option of pharmacologic inotropic support in patients with decompensated heart failure. In contrast to classic inotropes, rather than interfering with intracellular Ca(2+) levels in myocytes, levosimendan improves cardiac performance via Ca(2+) sensitization and K(+) channel-mediated peripheral vasodilatation. A two compartment pharmacokinetic model with zero-order input and first-order elimination has been found to describe best the pharmacokinetics of levosimendan. Although oral levosimendan has high bioavailability (approximately equal to 85%), in clinical practice it has been hitherto administered intravenously. Levosimendan has total clearance 175-250 mL/h/kg and most importantly a short half-life (about 1.5 hours). Therefore, this drug has a special pharmacokinetic interest: It is one of the few drugs used in cardiovascular medicine, whose prolonged action is not due to the drug itself but it is mainly due to its active metabolite OR-1896 (approximately 80 hours half life). Other metabolites with possible pharmacologic effect are N-conjugated OR-1855 (M7), N-hydroxylated OR-1855 (M8), N-hydroxylated OR-1896 (M10), O-glucuronide OR-1896 (M9) and O-sulfate (M11) of N-hydroxylated OR-1896. Initial reports on levosimendan's use in severe heart failure were positive and levosimendan has already been routinely used for the treatment of patients with decompensated heart failure, while it has been included to the European Society of Cardiology guidelines for the treatment of acute heart failure (class of recommendation IIb, level of evidence B). However, recent clinical trials have failed to demonstrate a clear benefit of levosimendan on survival, compared to other classic inotropic agents in patients requiring inotropic support. In this review article we provide a pharmacokinetic approach for the use of levosimendan in cardiovascular system by discussing its metabolism and mainly the pharmacology of its active metabolites in humans.