The effects of moisture on the rheological and elastic-plastic characteristics of compressible powders and the qualitative characteristics of tablets of aspartame-containing sweetener were studied. Theoretical and experimental studies identified the need for additional stages of moistening tableting material in pressing techniques.Aspartame-containing sweetener tablets have a number of advantages over others, namely the absence of energy content, a taste which is virtually identical to that of sugar, and the absence of the aftertaste typical of other sweeteners.Introduction of aspartame-containing sweetener tablet production involves a number of complications, making pressing difficult. It is therefore necessary to identify their causes and to optimize the technical process.Moisture is known to have direct effects on the plastic properties of particles -more moist materials are generally more plastic, while dry materials have elastic properties [1]. The presence of free moisture on particle surfaces helps to reduce friction when particles come closer together and also between the powder and the surface of the matrix. This leads to increases in the fluidity of powders [2] and decreases in friction when tablets are extruded from the matrix. Absorbed water also decreases the surface energy of crystals and increases the adhesion of tablets to the matrix and die surfaces and decreases their strength [3].Thus, published data provide evidence that the moisture of powders is an important factor in direct pressing technology, optimization of which allows increases in equipment productivity, increases in the quality of the ready product, and reductions in cost.The aim of the present work was to optimize the technology for tableting a standard sweetener containing 33.3% aspartame, 4.0% leucine, 4.0% sodium carboxymethylcellulose (NaCMC), and 58.7% lactose [4].The effects of moisture on the following were studied:-the rheological properties of tableting material (flowability, bulk density); -the energy characteristics of direct pressing (plastic particle deformation onset pressure and the pressure of extrusion of tablets from the matrix;-the quality parameters of tablets. MATERIALS AND METHODS Materials.Anhydrous lactose for direct pressing, Granulac-70 (Meggle, Germany) with a moisture content of 4.5 -5.5%, aspartame Powder-200 (HSC, Holland), leucine (USP 26), NaCMC (Cecol 5000), and water (Pharmacopoeia Article FS-42-2619-97) were used.Apparatus. A laboratory-scale hydraulic press with pressing pressures of up to 250 kgf/cm 2 , a matrix, a 5.2-mm diameter die, an MKI pointer micrometer with a precision of 0.01 mm, a Shimadzu balance model 200 (precision 0.001 g), an RTM-41 tableting press, and apparatus for assessing erosion, disintegration, and dissolution as specified in the State Pharmacopoeia, 11th Edition, were used.Methods. Experimental mixtures were prepared by placing 5.87 g of lactose in a mortar and moistening with different quantities of water. This was followed by addition of 3.33 g of aspartame, 0.40 g of leu...

The influence of lactose and microcrystalline cellulose on the flowability and moldability of tabletization mixtures and the quality of tablets obtained by direct molding has been studied. The optimum filler composition for direct molding is proposed. The possibility of replacing the wet granulation technology by direct molding is established for five well-known medicinal preparations.Many fillers that are used for direct molding of tablets, e.g., StarLac (Roquette, France) and Ludipress (BASF AG, Germany), are currently known. Despite the obvious advantages of using complex fillers for direct molding, the high cost hinders their incorporation into the domestic pharmaceutical industry.Use of lactose obtained by spray drying is very promising. This compound has several advantages (low cost and hygroscopicity, satisfactory flowability). However, it is highly crystalline. As a result, high pressures must be used for molding in order to obtain strong tablets [1].Another filler for direct molding is microcrystalline cellulose (MCC). A feature of this compound is the tendency of the particles to undergo plastic deformation [2]. This facilitates the production of strong tablets at low pressures [3]. However, use of MCC is hindered by the relatively high cost.We proposed using a mixture of lactose and MCC as the filler for direct molding of tablets. This would combine the advantages of each ingredient.Our goal was to develop a complex filler for direct molding. In order to achieve this goal, it was necessary to study the technological properties of the mixture, determine the optimum composition, and carry out tests of the proposed filler under direct molding conditions for several brand-name tabletted drug formulations. MATERIALS AND METHODS Materials.We used lactose for direct molding (Granulac-70, Meggle, Germany), lactose monohydrate (200 mesh), MCC (Avicell-10), calcium stearate, aerosil, and drug substances dibasol, dimedrol, vinpocetine, anaprilin, and papaverine hydrochloride according to current regulations.Equipment. We used a laboratory hydraulic press with molding force up to 250 kgs/cm 2 , matrices; 12-mm dies; an MKI indicating micrometer with 0.01-mm accuracy; PLT-24 tablet press (rotor rotation rate 16 rpm); instruments for determining wear, disintegration, and dissolution according to SP XI; and an RTU EL-102 (Germany) device for determining tablet fracture strength.Methods. Flowability and bulk density of tablet masses were determined by the usual methods [4]. The Heckel equation [5], ln[1/(1 -D)] = mP + b, where m is the slope; b, the Y intercept; P, the molding pressure; D, the ratio of tablet density to true density of the mixture (1.557 g/cm 3 , pycnometry); was used to compare elastic-plastic properties of the powders. Weighed portions of mixtures (0.500 g) were placed into the matrix of the tablet press (12-mm diameter), leveled, and molded at 30, 60, 90, and 120 kgs/cm 2 for 15 -20 sec. After this, the tablet mass (M, g) was determined and the tablet height (h, cm) was measured.Various amounts of ...

The effects of lactose and microcrystalline cellulose on the flowability and moldability of a tabletting mixture and the quality of tablets obtained by direct pressing have been investigated. The optimum composition of a complex filler for direct pressing of tablets is proposed. The possibility of replacing the technology of wet granulation by direct pressing for five well-known medicinal preparations is established.