A comparative study between conventional pan coater and quasi-continuous small batch coater on the stability of tablets containing acetylsalicylic acid

The Supercell coater was developed as an in-line small batch tablet coater which uses air-fluidization for tablet coating. Coating time is very much reduced, with improved heat and mass transfer. It was hypothesized that the quasi-continuous Supercell coating process was more suitable for the aqueous coating of tablets containing moisture-sensitive drugs. Acetylsalicylic acid (ASA) was used as the model drug in this study. The extent of ASA degradation in Supercell coating was compared against that of tablets coated using the conventional pan coater. Less than 0.3% of ASA was degraded at the end of the coating process using either coater. The extent of ASA degradation was found to be more pronounced during storage. The Supercell coated tablets exhibited comparable or smaller percentage of ASA degradation than the pan coated tablets at the end of a storage period of 6 months under accelerated stability conditions (40 °C/75% RH) and 3 years under ambient conditions (25 °C/50% RH). The extent and rate of ASA degradation during storage were dependent on the processing conditions employed during Supercell coating. Increase in temperature generally led to a reduction in ASA degradation, while increase in spray rate and coating level caused more degradation. Greater extent of ASA degradation was observed on the surface of pan coated tablets compared with Supercell coated tablets due to greater moisture contact and the slower and wetter coating process. Changes to the processing conditions also influenced the residual moisture content (0.55–2.86%) of the tablets. However, no direct correlation between the residual moisture content of the tablets after coating and the extent of ASA degradation during storage was found.

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