In vitro release kinetics of Tolmetin from tabletted Eudragit microparticles.

In a previous paper the preparation has been described, by three different techniques, of microparticles made of Eudragit RS 100 and RL 100 containing a NSAI agent, Tolmetin. Freely flowing microparticles failed to affect significantly the in vitro drug release, which displayed a similar dissolution profile after micro-encapsulation to the free drug powder. Microparticles were then converted into tablets and the effect of compression on drug delivery, as well as that of the presence of co-additives, was studied in the present work. Furthermore, microparticles were also prepared by adding MgO to the polymer matrix, to reduce the sensitivity of the drug to pH changes during its dissolution. Similarly, magnesium stearate was also used for microparticle formation as a droplet stabilizer, in order to reduce particle size and hinder rapid drug release. A mathematical evaluation, by using two semi-empirical equations, was applied to evaluate the influence of dissolution and diffusion phenomena upon drug release from microparticle tablets.

[1]  Roland Bodmeier,et al.  Tableting of coated pellets , 1997 .

[2]  M. Vachon,et al.  Physico-chemical evaluation of acetylsalicylic acid-Eudragit RS100 microspheres prepared using a solvent-partition method. , 1995, Journal of microencapsulation.

[3]  H. Toguchi,et al.  pH-independent controlled-release microspheres using polyglycerol esters of fatty acids. , 1994, Journal of pharmaceutical sciences.

[4]  P. Wehrlé,et al.  Evaluation of Spray-Drying as a Method to Prepare Microparticles for Controlled Drug Release , 1994 .

[5]  R. Gambari,et al.  Kinetics of bromocriptine release from microspheres: comparative analysis between different in vitro models. , 1994, Journal of microencapsulation.

[6]  R. S. Okor.  Drug release on certain acrylate methacrylate-salicylic acid coacervated systems , 1990 .

[7]  Y. Kawashima,et al.  Controlled Release Theophylline Tablet with Acrylic Polymers Prepared by Spray-Drying Technique in Aqueous System , 1990 .

[8]  Nicholas A. Peppas,et al.  A simple equation for description of solute release I. Fickian and non-fickian release from non-swellable devices in the form of slabs, spheres, cylinders or discs , 1987 .

[9]  M. Nakamura,et al.  Preparation and dissolution pattern of Eudragit RS microcapsules containing ketoprofen. , 1986, Chemical & pharmaceutical bulletin.

[10]  S. Benita,et al.  Fundamentals of release mechanism interpretation in multiparticulate systems: determination of substrate release from single microcapsules and relation between individual and ensemble release kinetics , 1986 .

[11]  A. Hoffman,et al.  Fundamentals of release mechanism interpretation in multiparticulate systems: the prediction of the commonly observed release equations from statistical population models for particle ensembles , 1986 .

[12]  J. C. Price,et al.  Preparation and Evaluation of Controlled Release Indomethacin Microspheres , 1984 .

[13]  S. Lin,et al.  Preparation of enteric-coated microcapsules for tableting by spray-drying technique and in vitro simulation of drug release from the tablet in GI tract. , 1980, Journal of pharmaceutical sciences.