Scaling up fluidised bed coating of sustained release microparticles at high spray rate using the MicroCoat™ technology

Scaling up fluidised bed coating of microparticles with particle size smaller than 150 µm is a challenge because of the high tendency of particle agglomeration. Consequently, the production yield of coating trials are unsatisfactory and low spray rate is typically applied leading to long duration of coating process.

The aim of this study is to scale up fluidise bed coating of microparticles at high spray rate using aqueous sustained release polymer dispersions by applying the proprietary MicroCoat™ technology. Click the poster to access:

Methods 
Metoprolol succinate layered microcrystalline cellulose cores (Cellets® 100) were coated using aqueous Eudragit® NM 30 D dispersion (Evonik AG, Germany) containing 100 talc (w/ based on dry polymer) as anti tacking agent.

The coating trials in a Mini Glatt were conducted with and without the application of the MicroCoat™ technology, whereby a dry powder glidant (magnesium stearate) was periodically added to the coating chamber during the coating process.

The coating process was scaled up in a MultiLab ® fluidised bed processor (Glatt GmbH, Germany) using placebo Cellets® 100 and the same coating formulation. The product yield was calculated based on the percentage of non agglomerated, free flowing particles after discharge.

Results
Significant particle agglomeration and aggregation was observed resulting in a low production yield of 55 without applying the MicroCoat™ technology 15 and 29 of particles were stuck in the down flow bed or the filter housing, respectively.
The coated particles showed non uniform size distribution with smaller particles collected from the down flow zone and the filter housing and much larger particles as free flowing particles after discharge.

Metoprolol release from the particles stuck in the filter housing and down flow zone was immediate indicating insufficient coating In contrast, drug release from the free flowing particles was slow, incomplete and with large variation, suggesting over coating.

Applying the MicroCoat™ technology completely eliminated particle agglomeration, with no stuck particles found in the filter housing or the down flow bed. Extremely high production yield was achieved at 99 8
The coated particles showed narrow and uniform size distribution. Uniform metoprolol release was achieved from coated particles with complete drug release at 20 h.

The coating process was successfully scaled up using the Glatt MultiLab® (High spray rate 10 g/min) was achieved No particle agglomeration or sticking on equipment was noticed with 100 production yield and 92 spray efficiency The coated particles showed uniform and narrow particle size distribution with 100 particles below 250 µm.

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