[Development and pharmacokinetic study of metoprolol tartrate controlled-release tablet remaining-floating in...

An oral controlled-release system (M-HBS) of metoprolol was developed based on the hydrodynamically balanced controlled drug delivery system. It was found that the in vitro release characteristics showed basically first-order kinetics (K'r = 0.1651 h-1); a tentative two-year expiration date on M-HBS was established; the gamma-scintiphotographic study after oral ingestion showed that M-HBS was retained in human stomach for longer time (5-6 h) than the conventional metoprolol tablet (1-1.5 h). The blood concentration-time course of M-HBS was demonstrated to fit a one-compartment model with apparent first order absorption and first order elimination. The parameters were calculated using a NONLIN computer program with the values of Ka, K, Vd, tmax, cmax, being 0.1944 h-1, 0.1867 h-1, 2.813, 5.247 h, 125.1 ng/ml, respectively. Moreover, the fraction of the dose absorbed from M-HBS in vivo well correlated with dissolution rate in vitro.