Clinicopharmacological studies of a newly synthesized cardiotonic agent (TA-064) in patients with congestive heart failure.

In animal experiments, a new inotropic agent, (-)-(R)-1-(p-hydroxyphenyl)-2-[(3,4-dimethoxyphenetyl)amino] ethanol, designated TA-064 was found to possess a more positive inotropic than chronotropic action. Its effectiveness and lack of significant toxicity make it beneficial for clinical use as a cardiotonic in human heart failure. The effects of TA-064 were investigated in patients with various types of heart disease (n = 29). Cardiac output increased, left ventricular end-systolic dimension decreased, and left ventricular fractional shortening increased for 15 minutes after a single intravenous dose (1 mg). The plasma level of TA-064 at the cessation of infusion was 61.1 +/- 49.6 ng/ml and thereafter declined biexponentially. After a single oral dose (10 mg), TA-064 appeared in the plasma at 30 minutes and reached its peak levels of 13.7 +/- 5.6 ng/ml at 60 minutes. Seven hours later, the plasma level was 5.9 +/- 3.1 ng/ml which was considered to be within the effective range according to the results after intravenous administration. In conclusion, minimal effective plasma levels of TA-064 are obtained by oral administration of 10 mg three times a day.