pentaacetylgitoxin and 16-acetylgitoxin

In ten patients suffering from moderate to severe disturbances of liver function (hepatic cirrhosis, carcinomatous metastases of the liver) the elimination of 16-acetyl-gitoxin from plasma was measured after a single oral dose of 1.2 mg pengitoxin. In 9 of 10 patients the mean half-life amounted to 67.3 h (SD 14.2 h). In one patient with carcinomatous infiltration of the liver and concomitant cirrhosis, the half-life was prolonged to 165.3 h. The results point to an unchanged elimination of 16-acetyl-gitoxin in patients suffering from liver cirrhosis.

Topics: Acetyldigoxins; Adult; Aged; Biotransformation; Digoxin; Half-Life; Humans; Liver Diseases; Middle Aged

The systolic time intervals (STI) corrected for changes in the heart rate, electromechanical systole (QS2c) and left ventricular ejection time (LVETc), and the ECG-derived PQ-time and QT-interval were measured in five female and four male healthy subjects. Each volunteer took 0.15, 0.30, 0.45, 0.60, 0.75 or 0.90 mg pengitoxin over six days, with a glycoside-free interval of two or three weeks between two doses. The glycoside plasma level was measured radioimmunologically. Linear correlations were found between the shortening of QS2, LVET, and QT (delta QS2c, delta LVETc, delta QTc) and the plasma level of 16-acetyl-gitoxin. The PQ-time showed a flat dose-dependent increase. The shortening of STI observed after therapeutic and subtoxic doses of pengitoxin was in accordance with that after intake of digitoxin and digoxin in corresponding doses. The efficacy of pengitoxin estimated by shortening of STI justifies the administration of daily maintenance doses between 0.30 and 0.45 mg.

Topics: Acetyldigoxins; Adult; Digoxin; Dose-Response Relationship, Drug; Electrocardiography; Female; Heart Rate; Humans; Male; Radioimmunoassay

In six volunteers the pharmacokinetics of 16-acetyl-gitoxin (16AG, 0.5 mg) administered intravenously (A1) and as an oral solution (A2) and of pengitoxin (PAG, 0.6 mg) administered intravenously (A3) was evaluated. In six volunteers the bioavailability of 16AG from two PAG tablet formulations (1.2 mg) (B2, B3) was measured by comparison with the absorption after administration of a pengitoxin solution (1.2 mg) (B1). In both studies the test was performed using a crossover design. After a single i.v. injection of equimolar doses, 16AG and PAG showed similar mean kinetic parameters: t1/2 = 51.6 hr (16AG) and 60.8 hr (PAG), CL = 11.7 ml min-1 (16AG) and 12.7 ml min-1 (PAG), CLR = 4.1 ml min-1 (16AG) and 4.2 ml min-1 (PAG). The 16AG was absorbed from solution with a mean half-life of 0.2 hr to an extent of 98.6%. The mean urinary excretion/Ae (0,4)/of 16AG amounted to 24.6% (A1), 20.8% (A2) and 28.1% (A3). On the basis of AUC values, the mean bioavailability of PAG from either tablet formulation amounted to 79.6% (B2) and 89.6% (B3). The pharmacokinetic parameters of 16AG (PAG) are closer to those of digitoxin than those of digoxin. In general, 16AG is characterized as a digitoxin with a digoxin-like elimination half-life.

Topics: Acetyldigoxins; Administration, Oral; Adult; Biological Availability; Digitoxin; Digoxin; Female; Humans; Injections, Intravenous; Kinetics; Male; Tablets

The pharmacokinetics of pengitoxin has been studied in 28 healthy subjects after intravenous and oral administration. The mean plasma concentration 24 h after 0.5 mg i.v. was 5.2 ng X ml-1. Following an open two-compartment model a mean elimination half-life of 60.5 h (24.9 to 103.5 h) and a mean volume of distribution (Vdarea) of 66.91 (31.8 to 109.61) were calculated. Absorption calculated by comparison of the AUC0-infinity-values amounted to 99%. Within 4 days, 16.7% (11.7 to 21.1%) or 27.8% (18.4 to 33.7%) (0.5 mg i.v. or 1.2 mg p.o.) was excreted in urine. After pengitoxin 0.5 mg i.v. total body clearance and renal clearance were 13.3 ml X min-1 (7.0 to 18.6 ml X min-1) and 3.0 ml X min-1 (1.9 to 3.9 ml X min-1) respectively. The elimination half-life of pengitoxin is longer than that of digoxin and distinctly shorter than that of digitoxin, whilst its distribution volume and clearance are closer to those of digitoxin than of digoxin.

Topics: Acetyldigoxins; Adult; Digoxin; Female; Humans; Kinetics; Male; Radioimmunoassay