Oral osmotic pump drug delivery systems: A narrative review of structural designs, functional mechanisms and emerging applications

Traditional oral formulations often lead to significant fluctuations in plasma drug concentrations. In contrast, oral osmotic pumps achieve zero-order drug release driven by osmotic pressure, which is largely independent of physiological variables, offering an effective solution to optimize drug delivery outcomes. This review aims to summarize the structural types, functional mechanisms, and key factors influencing drug release of oral osmotic pumps, compare their performance disparities, and provide valuable references for subsequent research and development in this field. Oral osmotic pump systems were classified based on their structural designs, their mechanisms of action and key drug release-influencing factors were elaborated, and the characteristics and application potential of different systems were comparatively evaluated. Oral osmotic pump systems can be categorized into single-chamber, multi-chamber, and specific types, with push-pull osmotic pumps particularly suitable for poorly soluble drugs and targeted systems enabling site-specific therapy. Drug properties, osmotic pressure, semipermeable membrane characteristics, and release orifice parameters are critical factors governing drug release. Despite advantages such as stable release profiles and broad applicability, the system is limited by complex preparation processes and high costs. Oral osmotic pumps represent a highly valuable drug delivery technology. Future integration with intelligent technologies and advanced materials is expected to overcome existing challenges, facilitating more precise and efficient drug delivery.