Spray drying of aqueous dispersions containing active ingredients for pharmaceutical purposes

The aim of this work was to prepare and characterize spray- dried pharmaceutical powders, and to optimize the variables of the spray drying [SD] process in order to obtain effective and stable drugs being released at the site of action. Two drugs were spray- dried, first bovine serum albumin [BSA], a protein model, was atomized in aqueous dispersions with ethyl cellulose [EC],second drug was sulfasalazine [SSZ] which atomized with eudragit [Eud] [gastro-resistant coating agent].Particle size distribution, shape and morphology, residual moisture, differential scanning calometry DSC thermograms, drug release profiles, yields, and encapsulation rate were studied. The best suitable conditions for the preparations of BSA were: solution feed rate of 4.38 ml/min, inlet temperature [Tin] of 160 C, outlet temperature [Tout] of 70 C, solid concentration content of 5.5%, and aspiration rate [Asp] of 80%.Microparticles [MP] produced by SD had spherical morphology but also there were disk- shaped particles of smooth surface with about 5 microm in dimension. The moisture content was 3.9%. BSA release profile in phosphate buffer showed sustained release, but almost perfect; 90% released after 8 hours, the yield of the process was about 69%,and the encapsulation efficiency [EE] was nearly 90%. The best conditions for the preparations of SSZ were: solution feed rate of 4.38 ml/min, inlet temperature [Tin] of 160 C, outlet temperature [Tout] of 80 C, solid concentration content of 2.8%, and aspiration rate of 80%. produced by SD had spherical morphology and there were some aggregations of smaller size, the particle median size was about 6.1 microm. The moisture content was 2.4%. SSZ release profile showed little drug release in the simulated stomach medium 15.9%after 2.5 hours, whereas it gave great release in the simulated intestine medium 93.1% for the same period of time. The yield of the process was about 65%, and the encapsulation efficiency [EE] was nearly 90%. These results confirmed that the spray drying methodology is an efficient, promising process for obtaining dried micro particles with specific and defined properties for pharmaceutical uses

[Studying the relationship between dissolution and absorption of the oral dosage forms locally manufactured containing macrolides and beta-lactam groups using Schulman cell]

The aim of the present study was to develop a model that can predict gastrointestinal absorption for a diverse range of drugs using the immobilized artificial membrane retention properties and the selected diffusion cell [schulman type]; the proposed method was employed to evaluate the apparent permeability of a set of 12 structurally diverse drugs having different solubility and permeability properties. An excellent linear correlation [R[2]=0.92] was obtained between the developed cell apparent permeability and human absorption data. A comparison of permeation data of some drugs obtained using retention properties of the immobilized artificial membrane [LAM] and the corresponding HIV values in humans further confirmed the proposed permeation method as predictor of the oral absorption of passively absorbed drugs. A comparative study between the permeability data for some solid dosage forms which belong to class III and class IV, and dissolution profile data can explain the effect of the permeability enhancers and formulation on the mechanism of drug absorption