Protection of Hygroscopic Pharmaceutical and Nutraceutical Active Ingredients via Film Coating Technologies: A Review

Hygroscopicity poses a significant challenge in the formulation of pharmaceutical and nutraceutical products, as moisture absorption often leads to chemical degradation, physical instability, and compromised therapeutic efficacy. This narrative literature review, evaluated the comparative effectiveness of various polymeric systems and coating technologies as moisture barriers across diverse dosage forms, including tablets, powders, granules, and particulates. We analyzed a spectrum of barrier materials, including cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol (PVA), methacrylates, and shellac, contrasting conventional solvent based techniques (fluid bed, spray drying, freeze drying coating) with advanced methodologies (hot melt coating, electrostatic dry coating, and Atomic Layer Deposition/ALD). Conventional coating systems utilizing HPMC and PVA were found to maintain moisture uptake below 1.5% during long-term storage (40°C/75% RH). However, more advanced strategies demonstrated superior protective capabilities, for instance, hotmelt coating employing lipid-based excipients (Precirol ATO 5) reduced moisture absorption by up to 85% at 75% RH. Furthermore, electrostatic dry coating showed a significant reduction in weight gain, decreasing from 6.5% to 3.3% compared to uncoated cores over a 48-hour period. Notably, ALD provided the most robust protection, preserving the amorphous stability of sensitive particles for up to two years under extreme conditions. This review highlights that film coatings not only mitigate moisture induced degradation but also enhance shelf life and improve the mechanical properties of dosage forms. These results underscore the versatility of coating technologies, enabling formulators to tailor strategies for highly moisture sensitive compounds.