Oral drug administration
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Oral Drug Administration: Patient Compliance, Simplicity, and Challenges
Oral drug administration is the most common and preferred method for delivering medications due to its non-invasiveness, ease of use, and high patient compliance. Patients favor oral drugs because they are simple to take and convenient for self-administration, making them suitable for both systemic and local treatments in the gastrointestinal (GI) tract Alqahtani2021Hua2020Homayun2019+1 MORE. However, more than half of therapeutic molecules are not available in oral form, especially biologics, due to significant challenges related to their physicochemical properties and stability in the GI environment .
Barriers to Oral Drug Absorption: Solubility, Permeability, and Metabolism
The effectiveness of oral drug delivery is limited by several physiological and pharmaceutical barriers. Key challenges include poor drug solubility, low permeability across the intestinal mucosa, enzymatic degradation, and instability in the acidic gastric environment Alqahtani2021Hua2020Xu2020+4 MORE. The presence of efflux transporters, tight junctions in the intestinal lining, and first-pass hepatic metabolism further reduce the bioavailability of many drugs, especially hydrophilic and high molecular weight compounds Azman2022Liu2022. Additionally, the gut microbiota and metabolic enzymes play crucial roles in drug metabolism and absorption, making the GI tract a complex site for drug delivery .
Strategies to Enhance Oral Drug Delivery: Nanocarriers, Mucoadhesive Systems, and Targeted Approaches
To overcome these barriers, researchers have developed various advanced drug delivery systems. Nanocarriers, micelles, cyclodextrins, lipid-based carriers, and mucoadhesive vehicles are being explored to protect drugs from degradation and enhance their absorption Alqahtani2021Xu2020Azman2022+2 MORE. Mucoadhesive carriers, in particular, can improve drug retention and controlled absorption in specific regions of the GI tract, making them promising for both local and systemic therapies . Targeting strategies that focus on specific cell types or regions within the GI tract, such as M cells for vaccines or L cells for diabetes treatment, are also gaining attention for their potential to improve therapeutic outcomes .
Innovative Technologies: 3D Printing, Microrobots, and Micro-/Nano-Fabrication
Recent advancements include the use of 3D-printed oral dosage forms, which offer superior control over drug release profiles and patient-centric designs compared to conventional tablets and capsules . Drug delivery microrobots, categorized by their driving mechanisms (magnetic, anchored, self-propelled, and biohybrid), are being developed to achieve targeted therapy and improve the bioavailability of biologics, addressing challenges that traditional oral treatments face . Micro- and nano-fabrication techniques are also enabling the creation of new oral drug delivery platforms that can better navigate the complex barriers of the GI tract .
Clinical Translation and Future Perspectives
While these innovative approaches show promise, challenges remain in translating them to clinical practice. Safety, scalability, and regulatory considerations must be addressed before widespread adoption. Continued research into the physiological and pathophysiological factors affecting oral drug delivery, as well as the development of predictive experimental models, will be essential for advancing the field Alqahtani2021Ren2024Hua2020+2 MORE.
Conclusion
Oral drug administration remains the most attractive and widely used route for drug delivery due to its convenience and patient compliance. However, significant barriers related to drug solubility, permeability, stability, and metabolism limit the effectiveness of many drugs, especially biologics. Advanced drug delivery systems, targeting strategies, and innovative technologies such as 3D printing and microrobots are being developed to overcome these challenges and improve oral drug bioavailability. Ongoing research and technological advancements are expected to further enhance the safety, efficacy, and patient-centricity of oral drug delivery systems.
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Oral drug delivery: Conventional to Long Acting New-Age Designs.
3D printed devices and formulations offer long-acting, efficient oral drug delivery, overcoming physiological barriers and improving patient compliance.
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