An evaluation of process parameters to improve coating efficiency of an active tablet film-coating process

Design of Experiments to Study the Impact of Process Parameters on Droplet Size and Development of Non-Invasive Imaging Techniques in Tablet Coating

“…The importance of droplet size on coating efficiency and quality has been reported, [14,24,25] with small droplets responsible for a more homogenous or even distribution of coating solution on the tablet surface [26,27]. More rapid water evaporation due to the greater volume to surface area ratio of small droplets [28–30] leads to greater coating efficiency [31]. Over-wetting, which can result in defects such as poor adhesion of coating polymer to the tablet surface, peeling, twinning, picking and sticking and tablet erosion [2,32], is thus less prevalent with smaller droplets.…”

“…Tablet defects, particularly poor adhesion can harm film functionality and negatively impact on the mechanical properties provided by a film coat. Typical droplet sizes in fluidised bed coating range between 20 and 100 μm, with coating efficiency reportedly being optimal below 10 μm, although this may run the risk of spray-drying of droplets before they reach the tablet surface [31,33]. To date no studies have investigated the direct impact of droplet size on tablet film coat using micro scale imaging.…”

Influence of relative humidity during coating on polymer deposition and film formation

“…The authors hypothesized that drug from the surface of the substrate could dissolve and physically mix with the forming polymeric film during C1 (higher RH). Indeed, the combination of the SR and AAP used in the C1 run likely resulted in the larger atomized droplets (Wang et al, 2012) and, hence, in the observed higher RH of the micro-environment in the coating pan in comparison to the conditions of C2; both of these factors could promote surface dissolution and subsequent physical mixing of ingredients at the substrate surface during film formation (Barbash et al, 2009). The fact that such behavior was observed for only A5 and B5 suggests that tablet porosity governs surface dissolution, rather than the hydrophilicity of the tablet formulation.…”

Scale Up of Pan Coating Process Using Quality by Design Principles

“…Spray rate is especially important if the formulation or API is sensitive or unstable under high‐moisture conditions, as residual water content in coated tablets has been shown to be directly related to spray rate and inlet air moisture . The ratio of spray rate and atomization air has been shown to dictate spray characteristics, such as droplet size . The rate at which the coating formulation is applied to tablets influences the tablet bed environment and thus the rate of solvent evaporation.…”