Safety of levosimendan and other calcium sensitizers

Levosimendan belongs to a new group of heart failure drugs, the calcium sensitizers. Because these compounds are not yet available for clinical use, the adverse drug events (ADEs) during levosimendan treatment cannot be predicted in detail. To evaluate the tolerability of levosimendan in human subjects, ADEs, safety laboratory values before and after treatment, and ambulatory ECG findings have been collected from several phase I and phase II clinical studies. By June 1994, approximately 200 subjects had received levosimendan. The most common ADE seen in healthy volunteers is headache, reported by some 40% of subjects in oral dosing but only 10% in i.v. dosing. The incidence of headache does not correlate well with the total daily dose of the drug. However, the controlled release formulations tested appear to cause vasodilatory symptoms more frequently than i.v. or rapid release oral formulations. The other typical vasodilatory ADEs seen in healthy volunteers are nausea, palpitation, and dizziness. Symptomatic hypotension is rarely encountered. It appears that heart failure patients tolerate the vasodilatory actions of the drug better than healthy volunteers. Only individual cases of headache, vertigo, and flushing have been reported, and injection site irritation has been the most commonly reported ADE (with an incidence <5%). However, because the longest administration of the i.v. infusion has been only 24 h, the duration of exposure to the drug is too short to allow any definitive conclusions to be drawn. All patients who have received levosimendan have been monitored with an ambulatory ECG. Even though some increase in heart rate is seen with high doses of the drug, there are thus far no signs of an increased incidence of ventricular tachyarrhythmias, nor have there been any noteworthy changes in the clinical laboratory safety tests. The experience with levosimendan is limited thus far and long-term data are lacking. It can be concluded, however, that at least in i.v. dosing the drug is devoid of ADEs with significant medical seriousness.