Pharmacokinetics of intravenous levosimendan and its metabolites in subjects with hepatic impairment.

Levosimendan is a vasodilator used in the treatment of acute heart failure. In the present study, the effect of hepatic impairment on the pharmacokinetics of levosimendan and its 2 metabolites, OR-1855 and OR-1896 (pharmacologically active), was investigated in 12 healthy subjects and 12 subjects with moderate hepatic impairment due to alcoholic cirrhosis of the liver but with no heart failure. In addition, the effect of acetylator status on the pharmacokinetics of levosimendan, OR-1855, and OR-1896 was evaluated. Safety and tolerability of levosimendan were also assessed. Levosimendan was given as an intravenous infusion of 0.1 microg/kg/min for 24 hours. Levosimendan showed similar C(max), AUC, and elimination half-life (t(1/2)), with a mean (+/-SEM) t(1/2) of 0.9 +/- 0.0 hours in healthy subjects and 0.8 +/- 0.1 hours in hepatically impaired subjects, respectively (not significant). The t(1/2) of OR-1855 was 61 +/- 5 hours in healthy subjects and 82 +/- 3 hours (P < .01) in subjects with hepatic impairment. The t(1/2) of OR-1896 was 62 +/- 5 hours and 91 +/- 5 hours (P < .01), respectively. However, the AUCs of OR-1855 and OR-1896 were similar in healthy volunteers and hepatically impaired subjects. The effect of acetylator status was seen as higher C(max) and AUC of OR-1855 in slow acetylators. Correspondingly, higher C(max) and AUC of OR-1896 were observed in rapid acetylators. Levosimendan was well tolerated in both study groups. In conclusion, the pharmacokinetics of the parent drug levosimendan was unaltered in subjects with moderate hepatic impairment, whereas the elimination of the metabolites was prolonged. However, because the maximum duration of levosimendan infusion is 24 hours, dosing adjustments of levosimendan may not be required in subjects with impaired hepatic function.

Pharmacokinetics and excretion balance of OR-1896, a pharmacologically active metabolite of levosimendan, in healthy men.

OBJECTIVE: To investigate the pharmacokinetics and excretion balance of [(14)C]-OR-1896, a pharmacologically active metabolite of levosimendan, in six healthy male subjects. In addition, pharmacokinetic parameters of total radiocarbon and the deacetylated congener, OR-1855, were determined. METHODS: OR-1896 was administered as a single intravenous infusion of 200 microg of [(14)C]-OR-1896 (specific activity 8.6 MBq/mg) over 10 min. The pharmacokinetic parameters were calculated by three-compartmental methods. RESULTS: During the 14-day collection of urine and faeces, excretion (+/-S.D.) averaged 94.2+/-1.4% of the [(14)C]-OR-1896 dose. Mean recovery of radiocarbon in urine was 86.8+/-1.9% and in faeces 7.4+/-1.5%. Mean terminal elimination half-life of OR-1896 (t(1/2)) was 70.0+/-44.9 h. Maximum concentrations of OR-1855 were approximately 30% to that of OR-1896. Total clearance and the volume of distribution of OR-1896 were 2.0+/-0.4 l/h and 175.6+/-74.5l, respectively. Renal clearances of OR-1896 and OR-1855 were 0.9+/-0.4 l/h and (5.4+/-2.3)x10(-4) l/h, respectively. CONCLUSIONS: This study provides data to demonstrate that nearly one half of OR-1896 is eliminated unchanged into urine and that the active metabolites metabolite of levosimendan remain in the body longer than levosimendan. The remaining half of OR-1896 dose is eliminated through other metabolic routes, partially through interconversion back to OR-1855 with further metabolism of OR-1855. Given the fact that the pharmacological activity and potency of OR-1896 is similar to levosimendan, these results emphasize the clinical significance of OR-1896 and its contribution to the long-lasting effects of levosimendan.

Effect of severe renal failure and haemodialysis on the pharmacokinetics of levosimendan and its metabolites.

BACKGROUND AND OBJECTIVES: Levosimendan is a calcium sensitiser developed for the treatment of congestive heart failure. It increases myocardial contractility, reduces the filling pressure and dilates both the peripheral and coronary vessels. The circulating metabolites of levosimendan, OR-1855 and OR-1896, are formed and eliminated slowly after intravenous administration of levosimendan. The aim of this study was to investigate the effect of impaired renal function and haemodialysis on the pharmacokinetics of levosimendan, OR-1855 and OR-1896. STUDY DESIGN: This study was an open-label, nonrandomised, phase I pharmacokinetic study. Levosimendan was administered as a single-dose infusion of 0.1 microg/kg/minute for 24 hours. The follow-up period lasted 3 weeks. STUDY SETTING: Twenty-fivepatients were included:12 patients with severe chronic renal failure (CRF) with creatinine clearance of < 30 mL/minute/1.73 m(2) and 13 patients with end-stage renal disease (ESRD) undergoing haemodialysis. A group of 12 healthy subjects served as controls. RESULTS: Levosimendan, the parent drug, was eliminated rapidly from the plasma after discontinuation of its infusion, with an elimination half-life (t(1/2)) [mean +/- standard error of mean] of 1.5 +/- 0.09 hours in ESRD patients undergoing haemodialysis, 1.0 +/- 0.2 hours in patients with severe CRF and 0.91 +/- 0.03 hours in healthy subjects. The t(1/2) of levosimendan was significantly longer (p < 0.001) in ESRD patients undergoing haemodialysis than in healthy subjects. The t(1/2) of OR-1855 and OR-1896 were 94.0 +/- 20.4 hours and 96.5 +/- 19.5 hours, respectively, in ESRD patients undergoing haemodialysis compared with 60.8 +/- 5.2 and 61.6 +/- 5.2 hours, respectively, in healthy subjects (p = not significant). The t(1/2) of OR-1855 was significantly longer (85.0 +/- 13.6 hours) in patients with severe CRF than in healthy subjects (60.8 +/- 5.2 hours, p < 0.05). The area under the plasma concentration-time curve (AUC) and the peak plasma concentration (C(max)) of the metabolites were approximately 2-fold in patients with ESRD undergoing haemodialysis and patients with severe CRF compared with healthy subjects. The mean unbound fraction (f(u)) of levosimendan in plasma was approximately 2% in each study group, whereas the f(u) of the metabolites was considerably higher (63-70%). In contrast to levosimendan, the metabolites were dialysable, with dialysis clearance of approximately 100 mL/minute. The haemodynamic responses and adverse event profiles were similar in the study groups, with headache, palpitations and dizziness being the most frequently recorded adverse events. CONCLUSION: The t(1/2) of the levosimendan metabolites was prolonged 1.5-fold and their AUC and C(max) were 2-fold in patients with severe CRF and ESRD patients undergoing haemodialysis as compared with healthy subjects. These results suggest that the dose should be reduced when levosimendan is used for the treatment of congestive heart failure in patients with severe renal insufficiency.

Entacapone improves the availability of L-dopa in plasma by decreasing its peripheral metabolism independent of L-dopa/carbidopa dose.

AIMS: Entacapone is a peripherally acting catechol-O-methyltransferase (COMT) inhibitor. To improve the benefits of oral L-dopa in the treatment of Parkinson's disease (PD), entacapone is administered as a 200 mg dose with each daily dose of L-dopa. This study evaluated the effects of entacapone 200 mg on the pharmacokinetics and metabolism of L-dopa given as standard release L-dopa/carbidopa. METHODS: Six different doses of l-dopa/carbidopa were investigated in this placebo-controlled, double-blind (regarding entacapone), randomized, single-dose study in 46 young healthy males. The subjects were divided into three groups (n = 14-16). Two different L-dopa/carbidopa doses were administered to each subject (50/12.5 mg and 150/37.5 mg, or 100/10 mg and 100/25 mg, or 200/50 mg and 250/25 mg). Each dose was given on two occasions; simultaneously with entacapone or with placebo, in random order, on two consecutive study visits, separated by a washout period of at least 3 weeks (four-way crossover design). Serial blood samples were drawn before dosing and up to 24 h after the dose and pharmacokinetic parameters of L-dopa, its metabolites, carbidopa, and entacapone were determined. RESULTS: Entacapone increased the AUC(0,12 h) of L-dopa to a similar extent at all doses of L-dopa/carbidopa, that is by about 30-40% compared with placebo (P < 0.001, 95% CI 0.15, 0.40). When evaluated as the ratio of geometric means, entacapone slightly decreased the mean C(max) values for L-dopa at all L-dopa/carbidopa doses compared with placebo. When given with entacapone, higher plasma concentrations of L-dopa were maintained for a longer period at all doses of L-dopa/carbidopa. Entacapone also decreased the peripheral formation of 3-O-methyldopa (3-OMD) to about 55-60% of the placebo treatment level (P < 0.001, 95% CI -0.72, -0.35) and increased the mean AUC(0,12 h) of 3,4-dihydroxy-phenylacetic acid (DOPAC) 2-2.6-fold compared with placebo (P < 0.001, 95% CI 0.60, 1.10). The mean AUC(0,12 h) of 3-methoxy-4-hydroxy-phenylacetic acid (HVA) following entacapone was approximately 65-75% of that observed with placebo (P < 0.001-0.05, 95% CI -0.76, -0.01) at each L-dopa/carbidopa dose except the 50/12.5 mg dose (P > 0.05, 95% CI -0.59, 0.05). The metabolic ratios (MR, AUC metabolite/AUC L-dopa) also confirmed that entacapone significantly decreased the proportion of 3-OMD (P < 0.001, 95% CI -0.85, -0.68) and HVA (P < 0.001, 95% CI -1.01, -0.18) in plasma at each L-dopa/carbidopa dose, whereas the AUC DOPAC/AUC L-dopa ratio was increased again at all doses (P < 0.001, 95% CI 0.26, 0.90). Entacapone did not significantly affect the pharmacokinetics of carbidopa at any of the doses, nor did L-dopa/carbidopa affect the pharmacokinetics of entacapone. CONCLUSIONS: The 200 mg dose of entacapone similarly and significantly increases the AUC of L-dopa by changing the metabolic balance of L-dopa independent of the L-dopa/carbidopa dose and therefore entacapone is likely to have a similar L-dopa potentiating effect independent of L-dopa dose.