Industrial Pharmaceutical Compression Faculty of Pharmacy OCTOBER 6 University

COMPRESSION : It is process of applying pressure to a material.an appropriate volume of granules in a die cavity is compressed bet. An upper & a lower punch to form a single solid matrix,the subsequent events are :1-transitional re-packing,2- deformation at points of contact, 3- fragmentation &/or deformation, 4- bonding, 5- deformation of the solid body,6-decompessio 7- ejection.

Formulation & processing are designed to ensure that the desired volume of granulation is fed into die cavity so that at a fast production rate & weight variation of final tab. Is minimal. Granules flow with respect to each other. Spherical part. Undergo less particle rearrangement then irregular part. To achieve a fast flow rate the granulation is processed to produce spherical or oval particles.

DEFORMATION at points of contact : when a stress is applied to a material, deformation occurs. If deformation disappears completely upon release of the stress, it is an ELASTIC DEFORMATION. When the granulation are so closely packed a further increase of compress ional force cause deformation at point of contact. Deformation increase the area of true contact & the formation of potential bonding areas.

Fragmentation & deformation : At higher pressure, fracture occurs with infiltration of the smaller fragments into the void space. Fragmentation increase the NO. of particles & forms new, surface that are potential bonding areas. BONDING : It occurs according to different MECHANISMS,MECHANICAL THEORY, INTERMOLECULAR THEORY, & liquid-surface film theory. In MECHENICAL the edges of the particles intermesh.

The mol. Or ions at surface of solid have SFE, which interacts with other particles in contact ( intermolecular force) to consolidate the particles. THE LIQUID – SURFACE FILM theory attributes bonding to the presence of a thin liquid film, which may be the consequence of fusion or solu., at surface of the particle induced by the energy of compression.

DEFORMATION OF THE SOLID BODY : As the pressure increased, the bonded solid is consolidated toward a limiting density. * DECOMPRESSION :The success or failure to produce an intact tab. Depends on the stresses induced by the deformation processes during decompression & ejection. A shape of tab. May be selected to reduce, exp flatfaced or oval tab.

EJECTION : During ejection that portion of tab. Within the die is under strain, & if this strain exceeds certain strength, problem of capping occurs.

PROPERTIES OF TABLET INFLUNCED BY COMPRESSION 1- Density & porosity : Density is related to applied pressure, until the limiting of the material is approached. Porosity is inversely prop. Log of applied pressure, so linear relation with negative slop. 2- Hardness & Tensile Strength : ability of tab. To withstand mechanical handling & transport, tests ( abrasion, bending, indentation, hardness, diametral, crushing ). There is linear relationship between tab. Hardness & log of applied pressure except at high pressure. The strength of a tab. May be expressed as a tensile strength, breaking stress of a solid unit cross section in kg/cm2

3- SPECIFIC SURFACE :It is the SA of 1gm of material.influence of applied pressure on SSA of tab. Is that the SS is increased to max. value indicating the formation of new surface. Further increase in pressure produce decrease in specific surface. 4- DISINTEGRATION : Usually, as the applied pressure is increased, the disint. Time is longer.

5- DISSOLUTION :4-common dissolution-pressure relation : A- more rapid diss. As applied pressure is increased. B- diss. Is slowed as applied pressure incr. C- diss. Is rapid as applied pressure incr. till max. & further increase in applied pressure slows dissolution. D- diss. Is slowed as applied pressure increase & then further increase in applied pressure speeds dissolution