A Strategy for Tablet Active Film Coating Formulation Development Using a Content Uniformity Model and Quality by Design Principles

Pharmaceutical Application of Tablet Film Coating

“…Active film coating is a process to coat a solid dosage unit (tablet or pellet) using a solution or suspension containing APIs as a coating solution. This coating technology meets formulation needs such as rapid drug release or improved product stability and is particularly useful for developing fixed-dose combination (FDC) products to control the drug release rate or physically block interaction between APIs [ 87 , 88 ]. Water-soluble drugs can dissolve in aqueous coating solution or suspension that can then be sprayed on core tablets.…”

“…Water-soluble drugs can dissolve in aqueous coating solution or suspension that can then be sprayed on core tablets. Therefore, it is easier to develop an active coating process for water-soluble drugs than water-insoluble drugs [ 87 ]. With water-insoluble drugs, particle size must be fine enough to prevent clogging of spray guns.…”

“…With water-insoluble drugs, particle size must be fine enough to prevent clogging of spray guns. Moreover, the drug suspension should remain homogenous during the coating process to obtain satisfactory content uniformity [ 87 ].…”

“…Major challenges in active coating include (1) determining the coating end point to achieve target potency, (2) ensuring tablet-to-tablet API content uniformity, and (3) maximizing coating efficiency (ratio of amount of APIs deposited on core tablets to amount of APIs sprayed) [ 13 , 32 , 87 ]. During active film coating, tablets are periodically sampled and analyzed for weight gain as well as the amount of API deposited on core tablets using an in-process assay [ 88 ].…”

“…Based on this in-process assay, additional amounts of coating suspension are further sprayed until the coating end-point is reached to obtain the target potency. When coating conditions, especially spray rate, remain constant during the entire coating process, a linear relationship was observed between the actual API amount deposited on core tablets and coating time [ 13 , 32 , 87 ]. Control on the spraying operation is also important to ensure the content uniformity in active film coating.…”