No abstract

The basic pharmacokinetics of bisoprolol were investigated in three independent studies involving 23 healthy volunteers. After administering 20 mg of 14C-bisoprolol orally, mean elimination half-lives of 11 hours for the unchanged drug and 12 hours for total radioactivity were observed. The enteral absorption of bisoprolol was nearly complete. Fifty percent of the dose was eliminated renally as unchanged bisoprolol and the other 50% metabolically, with subsequent renal excretion of the metabolites. Less than 2% of the dose was recovered from the feces. Intraindividual comparison of the pharmacokinetic data measured after oral and intravenous administration of 10 mg bisoprolol to 12 subjects yielded an absolute bioavailability of 90%. Total and renal clearance were calculated as 15.6 L/hr and 9.6 L/hr, respectively. The volume of distribution was 226 L. Concomitant food intake did not influence the bioavailability of bisoprolol.

The tolerance of Praziquantel (2-cyclohexylcarbonyl-1, 3, 4, 6, 7, 11b-hexahydro-2H-pyrazino-[2, 1-a]isoquinoline-4-one) in oral doses of 1 X 20 mg/kg, 1 X 50 mg/kg, 3 X 10 mg/kg and 3 X 25 mg/kg body weight (tau = 4 h) was tested in a complex study involving 36 healthy volunteers. In addition to the usual assessment of clinical chemistry, haematology, coagulation physiology, urinalysis, clinico-physiological examination including EEG, and medical examination, clinico-psychological parameters were also recorded and special neurological investigations were performed. No clinically relevant changes were found in any of the laboratory parameters, nor in the medical-neurological or clinico-physiological examinations. Based on a few clinico-psychological parameters and subjective comments, the largest daily dose tested (3 X 25 mg/kg = 75 mg/kg) produced a slight, transient disturbance in general well-being, which was barely detectable on objective clinical examination. The pharmacokinetic behaviour was dominated by rapid metabolism and pronounced first-pass metabolism of praziquantel, which greatly limits the value of results obtained by GC analysis of unchanged drug in serum. The peak concentration in serum was reached after 1--2 h, and the elimination half-life for the period 2--8 h was 1--1.5 h.

The pharmacokinetics of bisoprolol were investigated following oral administration of 10mg once daily for 7 days in 8 healthy subjects, in 14 patients with different degrees of renal impairment and in 18 patients with liver disease. In healthy subjects peak and trough steady-state concentrations of 52 micrograms/L and 11 micrograms/L, respectively, an elimination half-life of 10.0 hours and total body clearance of 14.2 L/h were observed. 5.21 mg/24 hours of unchanged bisoprolol were recovered following urinary excretion during the dosage interval. In 11 patients with renal impairment (mean CLCR = 28 +/- 5 ml/min/1.72m2) half-life was prolonged to 18.5 hours, and peak and trough concentrations were 74 and 32 micrograms/L, respectively. Correspondingly, urinary excretion decreased to 3.35 mg/24 hours and total body clearance to 7.8 L/h. In uraemic patients (CLCR less than 5 ml/min/1.73m2) the total clearance of bisoprolol was 5.0 L/h and the elimination half-life was 24.2 hours. In patients with liver cirrhosis half-life increased to 13.5 hours, steady-state peak and trough concentrations increased to 62 and 22 micrograms/L, respectively, and total body clearance decreased to 10.8 L/h. The present study indicates that in patients with impairment of kidney or liver function accumulation of bisoprolol above a factor of 2 did not occur. However, in the terminal stages of insufficiency of kidney or liver function bisoprolol dosage should not exceed 10mg.

No abstract