Controlled drug delivery systems

Drug delivery systems (DDS) have evolved significantly, offering advanced alternatives to conventional formulations. Among various administration routes, the oral route remains the most preferred due to its convenience and ease of industrial production. A critical aspect of modern DDS is the differentiation between controlled and sustained release mechanisms—each aiming to optimize therapeutic efficacy by modifying pharmacokinetic and pharmacodynamic profiles. Controlled release involves pre-designed drug release using polymers, whereas sustained release extends the drug's action over time, typically following first-order kinetics. DDS technologies have expanded to include nanobased delivery systems, molecularly imprinted polymers, and 3D printing, enhancing precision targeting, controlled drug localization, and overcoming biological barriers such as the blood– brain barrier. These systems also reduce toxicity, improve drug bioavailability, and minimize degradation. Solid dosage forms—tablets, capsules, lozenges, and granules—continue to dominate due to stability and patient compliance, while semisolid and bulk powders serve specialized therapeutic roles. Sublingual and buccal formulations further offer rapid systemic absorption by bypassing gastrointestinal and hepatic metabolism. Nanotechnology plays a pivotal role in DDS development. Liposomes, polymer micelles, and solid lipid nanoparticles significantly enhance drug solubility, stability, and tumor targeting while minimizing side effects. These advancements demonstrate the integration of multidisciplinary approaches to tailor drug delivery to specific physiological environments, supporting personalized medicine and improving therapeutic outcomes.