[Clinical effects and plasma concentration levels of aprindine hydrochloride in patients with tachyarrhythmias].

Aprindine hydrochloride (aprindine) was administered orally in 17 Japanese patients with supraventricular or ventricular tachyarrhythmias, and the clinical effects and plasma concentration levels were evaluated. The antiarrhythmic effects were defined using Holter ECG recordings. Aprindine was administered orally with a daily dose of 40 mg for 2 weeks in all cases, and aprindine, 60 mg daily, was administered for the next 2 weeks in patients who did not show sufficient antiarrhythmic effects with 40 mg of the drug. Aprindine was effective in 9 of 17 patients, and the mean plasma concentration level reached 0.6 micrograms/ml 2 weeks after the administration was started. Effective results were seen in 2 of the 4 patients receiving a daily dose of 60 mg, and the mean plasma concentration level reached 1.0 microgram/ml 2 weeks after the administration was started. Transient mild elevations of liver transaminases were observed in one patient and mild transient anemia was observed in another. These abnormal data disappeared although the drug administration was continued. In conclusion, the administration of a relatively small dose of aprindine and, consequently, low plasma concentration levels, are effective for cardiac tachyarrhythmias in Japanese patients.