Compression behaviour and tablet-forming ability of spray-dried amorphous composite particles

The aim of this study was to investigate the compression behaviour and tablet-forming ability of spray-dried amorphous two- and three-component composite particles. Particles of lactose alone, two-component particles of lactose and PVP, and three-component particles of lactose, PVP and a small amount of polysorbate 80 were prepared by spray-drying. Two qualities of PVP with different molecular weights were used for the preparation of both types of particles. The particles were characterised with respect to permeametry surface area, moisture content, particle and bulk density, glass transition and crystallisation temperature, and heat of crystallisation. The tablet tensile strength of the different particles formed at a series of applied pressures was determined and compression parameters were derived from the Heckel and Kawakita equations. The presence of PVP gave particles that were less prone to deform permanently during compression while the presence of surfactant gave particles that were less able to form tablets. In conclusion, the compression behaviour and tablet-forming ability of spray-dried amorphous lactose can be modulated by the addition of stabilising polymers or surfactants to the spray feed solution.

The influence of chitosan and sodium alginate and formulation variables on the formation and drug release from pellets prepared by extrusion/spheronisation

The influence of the incorporation of two oppositely charged hydrophilic natural polymers, chitosan and sodium alginate, alone and in combination, on the ability of formulations containing a model drug (paracetamol) to form spherical pellets by the process of extrusion/spheronisation and the properties of the pellets, has been undertaken. A statistically experimental design was employed to allow the major factors which determined the properties of the pellets, to be identified. A standardised procedure was used to prepare the pellets with a ram producing the extrudate for spheronisation. Statistical analysis of the results indicated that the formulation variables of the type and level of the polymer, the proportion of the model drug, and the proportion of the microcrystalline cellulose influenced (a) the quantity of liquid binder required to produce a good formulation (narrow size range and high value for the shape factor indicating sphericity), (b) the steady-state extrusion force, (c) the pellet perimeter, (d) the apparent pellet density and (e) the porosity of the pellets. The median size of the pellets of the "good formulation" could only be related to the chitosan and sodium alginate content of the formulations. The proportion of the drug, chitosan and sodium alginate content of the formulation significantly influenced the in vitro dissolution of the model drug (paracetamol). The drug release mechanism differed with the formulation variables, although if the pellets remained intact during the dissolution test, diffusion was the controlling mechanism. There was no significant advantage to be gained by using a mixture of the two polymers in terms of retarding drug release.