Film Coatings for Taste Masking and Moisture Protection

Taste masking and moisture protection of oral dosage forms contribute significantly to the therapeutic effect of pharmaceutical and nutraceutical formulations either by ensuring patient compliance or by providing stability through shelf life of the dosage form. Among different types of taste, bitter taste is the most relevant for patient acceptance because of the extremely high sensitivity. As hydrolysis is the most common mode of degradation of an active ingredient, moisture protection plays a vital role in the stability of the active during manufacturing and storage. Optimized oral dosage forms need to reliably hinder the release of bitter drug molecules in the mouth or ensure stability of the active compound, while also ensuring fast drug release in the stomach to enable early therapeutic onset. Besides different formulation concepts, film coating is found to be the most effective and commonly used approach for taste masking and moisture protection. Film coating can be achieved through the use of water-soluble, cationic, anionic or neutral insoluble polymers from different chemical structures. Cationic polymers provide efficient moisture protection as well as taste masking without influencing the release of the drug in the gastric fluids. Polymers may be sprayed onto various types of cores from dispersions or solutions in organic, solvents or water in drum or fluidzed bed coaters. Applied quantities need insuring complete coating thickness ranging from 0.5 to 50 μm or more finally. Insulating excipients, such as hydrophobic plasticizers, lipids, pigments or other insoluble substances will influence the functionality of films. Organoleptic tests are still common in testing the quality of taste-masked formulations. Recently, multi-channel taste sensors have been developed to quantify different types of taste. Dynamic vapor sorption technique and studies at elevated temperature provide effective concepts study the efficacy of the formulations. Efficient taste masking and reliable moisture protection of solid oral dosage forms can be achieved by film coating implementing the options of pharmaceutical polymers and processes.