Significant Reduction In Particle Cohesion During Fluid-bed Coating of Sustained Release Microparticles

Introduction Most oral dosage forms such as tablets and capsules are not suitable for paediatric and older patients with swallowing difficulties. Drug-containing sustained release microparticles are suitable to produce flexible dosage forms which are appropriate for these patients. The aim of this investigation was to apply a novel MicroCoatTM technology to improve coating process of small particles of less than 150 µm in size using aqueous sustained release polymer dispersions during Wurster fluid-bed coating. Methods Cellets 100 (D50 = 144µm) were coated using a Mini Glatt fluid-bed coater using aqueous Eudragit NM dispersion. This was done with and without using the MicroCoat™ technology where processing aids were added during coating through an external port. Coating outcomes were evaluated with regard to freely flowing particles (%FFP) and non- agglomerated particles post discharge. Cohesiveness and powder rheology of coated microparticles were observed with and without mixing with dry powder glidants (magnesium stearate, talc, silicon dioxide, glycerol monostearate) using GranuDrum rotating rheometer at room temperature. Results Without the application of the MicroCoatTM technology, a low yield of 27% was achieved. MicroCoatTM technology significantly improved yield to 99% by improving particle flow in the “down flow” zone and reducing particle aggregation (Fig 2) Using the GranuDrum rheometer (Fig 3), improved coating processing outcomes were explained as powdered glidants were shown to decrease the cohesiveness of coated microparticles. The glidants were ranked in the following order: silicon dioxide > magnesium stearate > talc > glycerol monostearate (Fig 4) Conclusions The addition of dry powder glidants during coating process significantly improved coating process and product yield of particles less than 150 µm size due to the reduction of particle cohesion and facilitating powder flow