We conducted a performance assessment study for a new sustained-release\r\ncapsule including starch-sponge matrix (SSM). The SSM, which is a support\r\nmedium for drug release, was made from 2.5% cornstarch glue by means of\r\nfreezing dry method. The SSM capsule was applied for nifedipine (NFP), a\r\ncalcium channel blocker, and evaluated pharmacokinetic and\r\npharmacodynamic (PK/PD) profiles of NFP after intraduodenal\r\nadministration of SSM capsules including 2.5 or 5.0 mg of NFP per capsule\r\nto rats. Plasma NFP concentrations from the SSM capsules showed dosedependent\r\nincreases with a Michaelis-Menten like behavior over 360 minutes\r\nafter intraduodenal administration. The values of area under the\r\nconcentration vs. time curve from time zero to 360 min (AUC0-360) of NFP\r\ndeclined in making SSM capsules as compared to control capsules due to a\r\nsimple physical mixture of NFP and cornstarch, but the values of mean\r\nresidence time (MRT0-360) extended and abidingness of SSM capsules were\r\nadmitted with dose-dependent manner. As for a PD parameter, the mean\r\narterial blood pressure (mABP) derived from the SSM capsules showed\r\n15~20% decrease of baseline within 120min after intraduodenal\r\nadministration, and thereafter the mABP in 2.5 mg SSM capsule was\r\ngradually recovered, while a relatively smooth and even change was found in\r\nthe mABP at 5.0 mg SSM capsule. The relationships between plasma NFP\r\nconcentration and sampling-time corresponding mABP after intraduodenal\r\nadministration of SSM capsules showed no rapid change in the mABP,\r\nindicating that a sustained-release mechanism due to the SSM functions\r\nsufficiently to avoid a fluctuating blood pressure accompanied by going up\r\nand down of plasma levels of NFP. The SSM capsules exhibited a sustainedrelease\r\npharmacokinetics of NFP, and made the fluctuation range with blood\r\npressure small compared to the physical mixture preparations. Thus, it was\r\nevidenced that the SSM capsule is useful device to provide a sustainedrelease\r\nsystems and optimal therapeutic efficacy of drugs.
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