A clinical trial conducted by University of Hull in the U.K. shows the drug omecamtiv mercabil improves the heart’s ability to pump blood in heart failure patients. The findings by Hull cardiology professor John Cleland and colleagues appear in the 20 August issue of the journal The Lancet (paid subscription required).
Omecamtiv mercabil is one of a new class of drugs called cardiac myosin activators that target the motor proteins that cause muscle contraction. Cardiac myosin activators prolong the interaction between the motor proteins myosin and actin to prolong the contraction of the left ventricle, the heart chamber which pumps oxygenated blood to the rest of the body. As a result, omecamtiv mercabil lengthens the time that heart muscles contract, which increases the volume of blood the heart pumps with each beat.
The study involved 45 heart failure patients with impaired function of the left ventricle in the U.S., U.K., Russia, and Georgia enrolled in a double-blind, randomized, placebo controlled, dose-escalation phase 2 clinical trial. Omecamtiv mecarbil was given intravenously for 2, 24, or 72 hours. The 45 patients received 151 infusions of either the active drug or a placebo.
The primary objective of the trial was to assess the drug’s safety and tolerability, with a secondary goal of evaluating the relationship between the plasma concentration of omecamtiv mecarbil and cardiac functions, to define concentrations for future trials. Clinical assessments of the patients — including vital signs, echocardiograms, and electrocardiographs — and testing of plasma drug concentrations took place during and after completion of each infusion.
The results showed omecamtiv mecarbil increased the duration of left ventricular contraction and the amount of blood expelled. At the same time, the drug did not increase the heart’s energy expenditure, which suggests the heart was working more effectively and efficiently. For patients tolerant of all the drug’s infusions, the researchers found no consistent pattern of adverse events with either dose or duration of treatment.
Cytokinetics Inc., a biotechnology company in South San Francisco, California is the developer of omecamtiv mercabil and sponsor of the trial. Cytokinetics has licensed the drug to Amgen Inc. for further development and commercialization, including a phase 2b clinical trial of omecamtiv mecarbil in patients with left ventricular systolic dysfunction hospitalized for acute heart failure.
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