Prescription design of tablet press

Prescription design of tablet press

Compressibility: Compressibility refers to whether the material is easy to compress into pieces. The formability of the material can be evaluated by hardness, tensile strength and elastic recovery rate of the tablet. The tablet should be of the right hardness and should also ensure that the tablet disintegrates quickly or the drug dissolves quickly. When the content of the main drug in the tablet is small, pharmacy method should be used to achieve the purpose of uniform distribution of the drug, under normal circumstances, it is appropriate to use simple excipients; When the content of main drug in tablets is large, attention should be paid not only to the fluidity and compressibility of excipient, but also to its capacity and the amount of excipient, and also to the influence of particle size and form of active ingredient on the compressibility. Compressibility is related to the plasticity and elasticity of raw materials and the microscopic state of material particles. Microcrystalline cellulose has a spongy porous tubular structure, easy to deform, so it is commonly used as a dry adhesive with good compressibility. In general, the first consideration is the use of microcrystalline cellulose, the amount of which can be up to 65%. However, when several excipients are used together, the compressibility will change. For example, when lactose and microcrystalline cellulose are used together, the additive effect will occur. When sucrose powder and microcrystalline cellulose are mixed, the antagonistic effect is produced.

Fluidity: the fluidity of the mixture material for powder direct tablet pressing not only directly affects the filling of die hole and the difference of tablet weight, but also plays an important role in the uniformity of powder mixing, which is more important in high-speed tablet pressing machine. Therefore, in the design of prescription, in addition to the selection of appropriate diluent, but also need to use a flow aid to increase the fluidity of the powder mixture. Powder fluidity is usually indicated by Angle of repose or outflow velocity, etc. The Angle of repose is determined by fixed funnel method, fixed cone bottom method and inclined box method, etc. It is generally believed that the fluidity is better when the Angle of repose is less than 30 degrees. Above 40 degrees, the fluidity is poor.

Lubricity: Lubricity refers to the degree of lubrication on the surface of the powder. Two aspects should be paid attention to when investigating the lubricity of drug powder mixture: one is the relationship between the nature and fineness of raw material powder and the variety and dosage of lubricant; Second, the lubricant can soften the tablet, the smaller the powder of the drug, the more the amount of lubricant is needed, the more obvious the softening effect.