LORCAINIDE INFUSION IN THE TREATMENT OF VENTRICULAR PREMATURE BEATS (VPB)

The plasma level and antiarrhythmic effect of lorcainide (R 15889) have been investigated in 15 patients with ventricular premature beats (VPB). Therapy was initiated with an intravenous dose of 1.9 mg/kg given over 10 min, followed by a constant infusion of 0.18 mg/kg/h for 24 h. In 8 patients the corresponding doses were increased to 2 mg/kg and 0.27 mg/kg/h. After the intravenous doses patients were treated orally with 100 mg tid for 6-7 days. The two dosage regimens were selected so as to achieve theoretical steady-state plasma levels (css) of 200 and 300 ng/ml, respectively. The combined intravenous treatment approached (181 ± 6.8 ng/ml and 273±28.5 ng/ml, respectively) the desired css within 2 to 4 h. During the oral administration, the minimal plasma concentrations following the lower intravenous dose (184±18 ng/ml) were significantly (p=0.0001) lower than after the higher intravenous dose (264±20.5 ng/ml). The dealkylated metabolite of lorcainide was not detectable after the intravenous doses, but it accumulated during oral treatment, when its concentration exceeded that of the parent compound. In 5 of the 7 patients receiving the lower dose VPB were effectively reduced. However, in only 4 of the 8 patients on the higher dosage schedule could a significant antiarrhythmic effect be demonstrated. In addition, side effects were observed in 6 of the subjects. © 1979 Springer-Verlag.