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To make rapidly disintegrating tablets with sufficient mechanical integrity as well as a pleasant taste, microcrystalline cellulose (MCC), Tablettose (TT), and crosslinked sodium carboxymethyl cellulose (Ac-di-sol) or erythritol (ET) were formulated. Tablets were made by a direct compression method (I). Tablet properties such as porosity, tensile strength, and disintegration time were determined. The tensile strength and disintegration time were selected as response variables, tablet porosity and parameters representing the characteristics of formulation were selected as controlling factors, and their relation was determined by the polynomial regression method. Response surface plots and contour plots of tablet tensile strength and disintegration time were also constructed. The optimum combination of tablet porosity and formulation was obtained by superimposing the contour diagrams of tablet tensile strength and disintegration time. Rapidly disintegrating tablets with durable structure and desirable taste could be prepared within the obtained optimum region.

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To control drug release is a topic of much interest. Matrix systems were often used as one method to control drug release. Higuchi mathematically showed the drug release properties of matrix systems, 1) and numerous investigations have been carried out since then. Based on the component, matrix systems can be roughly classified into two types, i.e., polymer and wax matrix systems. Drug release from a polymer matrix is likely to be accompanied by dissolution and/or swelling of matrix layer, and the shape and size of the matrix system varies with release time. Thus polymer matrix systems involve complicated conditions. Compared with polymer matrix systems, wax matrix systems are considered to retain the initial form. To control drug release, it is important to maintain some basic properties of the matrix system. Considering the above difference, the release properties of wax matrix systems should be investigated at first.When a wax matrix system is prepared from melted granules of soluble component and wax, troublesome factors such as surface coverage and thickness of wax on the soluble component must be considered. On the other hand, when a wax matrix system is prepared using a physical mixture of soluble component and wax, basic release properties can be estimated by connecting their basic properties and simple factors.Therefore, wax matrix tablets were prepared from a physical mixture, and basic release properties were examined by the measurement of release from the single flat surface or curved side surface of the tablets. ExperimentalMaterials Isoniazid JP (INZ, Yukigousei Yakuhin Kogyo Co.) was pulverized to about 7 mm prior to use. Hydrogenated caster oil (HCO, Kawaken Fine Chemical Co.) was used as the matrix substance. 2) Preparation of Physical Mixture for Wax MatrixThe mixed weight ratio of INZ to HCO powder was fixed at 7 : 3. The appropriate amounts of INZ and HCO powder were physically mixed using an automatic mixer (type S 10, Taiyo Kagaku Kogyo Co.). Preparation of Tablets for Release from One Flat SurfaceThe amount of physical mixture was fixed at 0.50 or 1.20 g for tablets 10 or 16 mm in diameter, respectively. The physical mixture was put into a die and compressed at 1273 kg/cm 2 with flat-faced punch (model clean press correct 12 HUK, Kikusui Co., Ltd.). A tablet was placed at the center of a die of 16 or 20 mm and the appropriate amount of HCO powder was added. Then the content was compressed at 637 kg/cm 2 . Preparation of Tablets for Release from Curved Side SurfaceUsing the appropriate amount of HCO and the physical mixture of 0.50 or 1.20 g, three-layered tablets 10 or 16 mm in diameter were prepared with compression force of 1273 kg/cm 2 . Release Test A dissolution apparatus (model NTR-VS, Toyama Sangyo Co., Ltd.) coupled to a flow cell set in a double-beam spectrophotometer (model 200-20, Hitachi Ind. Co.) via a microtube pump (model MP-3, Tokyo Rikakikai Co., Ltd.) and pen recorder (model 3056, Yokogawa Electric Works, Ltd.) was used. Release measurement was carried out in 900 ml of di...

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To make rapidly disintegrating tablets with sufficient mechanical integrity, tablets were prepared by compressing wet granules under low compression force and then drying the resulting wet mass in a circulating-air oven (wet compression method). Lactose with various particle sizes was used as the excipient, and water was used as a wetting agent. The effect of drying time, compression force, size of lactose particles, and moisture content of wet granules on tablet properties indicated that the formation and disintegration time of tablets were related to the effect of the formation of solid bridges between lactose particles. By optimizing compression force, size of lactose particles, and moisture content of the granules, tablets meeting tensile strength greater than 0.5 MPa and disintegration time shorter than 15 s were obtained by the wet compression method.

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The release properties of phenylpropanolamine hydrochloride (PPA) from ethylcellulose (EC) matrix granules prepared by an extrusion granulation method were examined. The release process could be divided into two parts; the first and second stages were analyzed by applying square-root time law and cube-root law equations, respectively. The validity of the treatments was confirmed by the fitness of a simulation curve with the measured curve. In the first stage, PPA was released from the gel layer of swollen EC in the matrix granules. In the second stage, the drug existing below the gel layer dissolved and was released through the gel layer. The effect of the binder solution on the release from EC matrix granules was also examined. The binder solutions were prepared from various EC and ethanol (EtOH) concentrations. The media changed from a good solvent to a poor solvent with decreasing EtOH concentration. The matrix structure changed from loose to compact with increasing EC concentration. The preferable EtOH concentration region was observed when the release process was easily predictable. The time and release ratio at the connection point of the simulation curves were also examined to determine the validity of the analysis.