Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions
This study concerned the quality of mini-tablets’ coating uniformity obtained by either the bottom spray chamber with a classical Wurster distributor (CW) or a swirl distributor (SW). Mini-tablets with a diameter of 2.0, 2.5, and 3.0 mm were coated with hypromellose using two different inlet air distributors as well as inlet airflow rates (130 and 156 m3/h). Tartrazine was used as a colorant in the coating layer and the coating uniformity was assessed by spectrophotometric analysis of solutions obtained after disintegration of the mini-tablets (n = 100). Higher uniformity of coating material distribution among the mini-tablets was observed in the case of SW distributor, even for the biggest mini-tablets (d = 3.0 mm), with an RSD no larger than 5.0%. Additionally, coating thickness was evaluated by colorimetric analysis (n = 1000), using a scanner method, and expressed as a hue value. A high correlation (R = 0.993) between inter-tablet variability of hue and UV-Vis results was obtained. Mini-tablets were successfully coated in a fluid bed system using both a classical Wurster distributor as well as a swirl generator. However, regardless of the mini-tablets’ diameter, better film uniformity was achieved in the case of a distributor with a swirl generator.
Download the full article here: Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions
or continue reading here: Turk, M.; Šibanc, R.; Dreu, R.; Frankiewicz, M.; Sznitowska, M. Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions. Pharmaceutics 2021, 13, 746. https://doi.org/10.3390/pharmaceutics13050746
More about microcrystalline cellulose
Materials
Cores: microcrystalline cellulose (Vivapur 102, JRS Pharma, Rosenberg, Germany), sodium stearyl fumarate (PRUV, JRS Pharma, Rosenberg, Germany), spray-dried lactose (Flowlac 100, Meggle Pharmaceutical, Wasserburg, Germany), colloidal silicon dioxide (Aerosil 200, Evonik Industries AG, Darmstadt, Germany).
Coating: hypromellose (HPMC, Pharmacoat 606, Shin-Etsu Chemical, Tokyo, Japan), polyethylene glycol (PEG 6000, Sigma-Aldrich, Steinheim, Germany), tartrazine (Sigma-Aldrich, Steinheim, Germany).
Conclusions
Mini-tablets can be coated in a fluid bed system using both classical Wurster distributors as well as swirl generators. However, based on the results of UV-Vis analysis of the coating tracer, better film uniformity (regardless of the mini-tablets diameter) was achieved in the case of the distributor with a swirl generator. While using the same process conditions and the same process chamber, higher coating variability was always observed for bigger mini-tablets (3.0 mm diameter) than for the smaller ones (diameter of 2.5 or 2.0 mm). Increased air fluidization velocity always improved the coating uniformity of mini-tablets. It is assumed that the mixing in the annulus region, as well as the gap size, are the limiting factors that determine mini-tablet coating thickness variability. Hardness testing showed an increase in hardness for coated mini-tablets as well as good correlation with the coating thickness variability pattern. It was also demonstrated that imaging with color analysis can provide quick and reliable results concerning mini-tablet coating thickness variability. A high correlation between the inter-mini-tablet variability of hue and UV-Vis results was obtained, which indicated the usefulness of non-destructive, fast and easy color analysis, performed with a scanner, to evaluate film thickness on a large number of mini-tablets.