Oral Gastro-resistant Formulations - State of the Art, Advances and Prospects: A Review

Gastro-resistant oral dosage forms remain essential for protecting acid-labile active pharmaceutical ingredients, reducing gastric irritation, and enabling site-specific intestinal or colonic drug delivery. Although conventional enteric coatings are well established, their in vivo performance remains affected by gastric pH variability, food intake, alcohol exposure, gastric residence time, coating integrity, and interindividual differences in gastrointestinal transit. Advanced platforms, including ready-to-fill enteric capsules, hot-melt technologies, three-dimensional printing, electrospinning, micro- and nanocarriers, and pH-responsive hydrogels, have been proposed to overcome these limitations, but many remain at an experimental or early translational stage. This narrative review critically evaluates gastro-resistant oral formulations from technological, physiological, and regulatory perspectives. It compares established and emerging technologies with respect to release mechanisms, material requirements, processing constraints, acid-resistance performance, translational maturity, scalability, regulatory acceptability, and commercial feasibility. Recent advances, including rapid-release double-coating concepts and dual pH- and microbiota-triggered colonic delivery systems, are also discussed. Overall, the field is moving from simple gastric protection toward more predictive and functionally complex oral drug delivery platforms. Future progress will depend on biorelevant dissolution testing, stronger in vitro-in vivo correlations, quality-by-design approaches, process analytical technologies, greener manufacturing, and regulatory pathways capable of accommodating innovative materials and personalized oral therapeutics.