The steady state pharmacokinetics and pharmacodynamics of metoprolol controlled release tablets 100 mg CR/ZOK, was compared with those of metoprolol conventional tablets 100 mg (CT) and atenolol 50 mg (ATL) in ten healthy Oriental men. The study was of double-blind, cross-over placebo controlled design. The three study drugs and placebo were given in a random order once daily for 4 consecutive days with 1-week wash-out between each period. Treadmill exercise tests were performed and blood samples were obtained at fixed intervals after the fourth dose of each treatment. There was less fluctuation in the plasma level-time profile after CR/ZOK than CT and ATL. Plasma concentrations were significantly higher on CR/ZOK than CT at 24 hours after dosing. The relative bioavailability of CR/ZOK to CT was 69.0%. CR/ZOK achieved relatively more uniform beta-blocking effect over the dose interval. Compared to CT and ATL, the peak effect after CR/ZOK was less pronounced and the beta-blockade after 24 hours more effective.
Aims To investigate dose proportionality, dosing frequency, and ethnic aspects of the pharmacokinetics of bambuterol in asthmatic children, and to discuss the relationship with previous observations in adults. Methods Forty-eight children in four different studies completed two double-blind bambuterol treatments each (daily doses of bambuterol hydrochloride): 12 preschool (5 mg×2 vs 10 mg ) and 12 school (10 mg vs 20 mg ) Caucasians, 12 preschool (2.5 mg vs 5 mg), and 12 school (10 mg vs 20 mg ) Orientals. Peak plasma concentrations and dosing interval area under curve (AUC) of bambuterol and the active metabolite terbutaline were assessed at steady state. Treatment differences were analysed statistically within each study. Differences between the studies and the relation to steady-state AUC in adults were described.
A double-blind, crossover comparison of the pharmacokinetics and pharmacodynamics of controlled-release metoprolol (CR) 100 mg and 200 mg, metoprolol plain tablet 100 mg, metoprolol Durules 200 mg, and placebo was carried out in 10 healthy Chinese subjects. Standardized treadmill exercise tests according to the Bruce protocol were performed at a steady state of medication, before and 2, 6, 12, and 24 hours after the dose, and multiple blood samples were collected for determination of the metoprolol concentration. The plasma metoprolol levels over 24 hours were more uniform after metoprolol CR than Durules and the plain tablet. The mean peak concentrations for CR 100 mg, 200 mg, Durules, and the plain tablets were 231, 426, 790, and 1105 nmol/l, respectively. The corresponding fluctuation incides were 1.1, 1.5, 2.2, and 5.0. The effects on exercise heart rate (EHR) were investigated at steady state. Metoprolol CR produced more even reduction in EHR over 24 hours than Durules and plain tablets. All four treatments gave similar maximal reduction in EHR of about 20% at 2 hours after the dose. In conclusion, once daily metoprolol CR showed almost even blood levels and provided relatively constant levels of beta1 blockade over 24 hours in healthy Chinese subjects.
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