Introduction
Drug delivery systems are the methods employed for transporting and delivering drug molecules into the desired locations of our body for the desired therapeutic outcomes. Traditionally, pharmaceutical compounds have targeted cell surface receptors, often introduced into our bodies without specific molecular delivery mechanisms. However, many promising new medicines are designed for delivery inside cells and, as such, require advanced drug delivery systems (ADDS) for targeted release into cells and tissues to optimize their beneficial effects. These new ADDS elevate the safety and efficacy of drug formulations and profoundly impact our healthcare by minimizing systemic side effects, increasing therapeutic benefits and improving patient compliance.
Types
Three main categories of advanced drug delivery systems are used to enhance the precision, efficacy and safety of drug delivery. They are (1) nanoparticle-based drug delivery systems, (2) polymeric drug delivery systems, and (3) targeted drug delivery systems.
Nanoparticle-based delivery systems
These delivery systems utilize particles ranging from 1 to 100 nanometers. They commonly deliver small drug molecules, proteins or nucleic acids (DNA or RNA) across biological barriers. Common examples include:
Liposomes: These are spherical lipid bilayer vesicles that can encapsulate drugs for targeted delivery. Their main application includes the site-specific killing of tumor cells in cancer therapy. Also, liposomes increase the stability and solubility and decrease the toxicity of drugs.
Dendrimers: These are highly branched star-shaped macromolecules used for the precise delivery and controlled release of drugs into the site of action.
Solid lipid nanoparticles (SLNs): These are stable biodegradable systems that can improve the bioavailability of poorly water-soluble drugs.
Polymeric delivery systems
These advanced drug delivery systems prevent the degradation and control the release of pharmaceutical molecules by encapsulating them in a polymeric coat. Some examples include:
Biodegradable polymers: Common examples include polylactic acid (PLA) and polyglycolic acid (PGA). Once introduced into our body, these polymeric molecules release drugs, but the remaining products are non-toxic, and hence, no surgery is needed for their removal.
Hydrogels: These water-absorbing three-dimensional polymeric networks are mainly used in localized drug delivery in tissues, where they release the active drugs in response to changes in temperature or pH.
Microneedles: These microscopic needles can penetrate the skin’s outer layer and are used in a minimally invasive way to deliver drugs into dermal tissue.
Targeted delivery systems
These delivery systems are designed for the direct site-specific release of drugs, and hence, they reduce the side effects and increase the therapeutic efficacy. Examples include:
Antibody-mediated targeting: These delivery methods use antibodies that attach specifically to antigens on target cells, such as tumor cells, to release cytotoxic drugs directly.
Ligand-receptor targeting: These delivery methods use ligand molecules that can bind to specific receptors on target cells, enhancing drug entry into cells.
Gene delivery systems: These delivery methods use viral or non-viral vectors to deliver nucleic acids into cells, especially in some genetic conditions.
Stimuli-responsive delivery systems
These delivery systems are commonly utilized to ensure that the drug is only released when needed by releasing the drug molecules in response to specific triggers. Examples include:
pH-responsive: These systems use different pH levels (like the lower pH in tumor tissues compared to regular tissues) in various body compartments to trigger the release of drugs.
Temperature-responsive: These delivery systems comprise unique polymer molecules that can alter their structure at different temperatures to release drugs. They are commonly employed in localized conditions like tumors or infections.
Light-responsive: These systems involve materials that change their properties when exposed to light, leading to controlled drug release to light stimuli. These systems are commonly helpful in treating skin diseases.
Applications of Advanced Drug Delivery Systems
Advanced DDS is vital for managing various medical conditions, offering enhanced solutions across various medical specialities.
Oncology: Targeted delivery systems enhance efficacy and reduce side effects of cancer chemotherapy.
Cardiovascular diseases: Enable controlled release of medicines and improve treatment outcomes of blood pressure and cardiac rhythm.
Neurological conditions: Next-generation drug delivery systems assist in the direct delivery of the therapeutic into the brain, thereby offering innovative strategies to combat diseases such as Alzheimer’s and Parkinson’s.
Autoimmune diseases: Advanced drug delivery systems reduce systemic adverse effects and improve treatment outcomes in many autoimmune diseases by precisely delivering drug molecules to affected areas.
Vaccine delivery: Improve the efficacy of vaccines by facilitating immune response and the controlled release of drug molecules.
Advantages of Advanced Drug Delivery Systems
Next-generation advanced drug delivery methods provide excellent benefits over traditional drug delivery systems. Some of these advantages include:
Enhanced bioavailability: These latest systems offer ideal drug absorption and utilization within the human body.
Reduced side effects: Targeted delivery of drug molecules reduces adverse effects by minimizing the exposure of drugs to non-target regions.
Improved patient compliance: Controlled release of drugs reduces frequent dosing schedules, leading to improved patient adherence to treatment.
Targeted therapy: The precise delivery of therapeutics to desired cells or tissues within the body improves the effectiveness of therapy.
Personalized medicine: Advancements in drug delivery methods help to tailor the treatment strategy based on individual patient needs.
Challenges of Advanced Drug Delivery Systems
There are several limitations to advanced DDS in patient care, some of which include the following:
Biocompatibility and toxicity: The materials used to deliver drugs should be safe and non-toxic for human use.
Stability and storage: Many advanced delivery systems require tailored storage conditions, which poses logistical and operational challenges.
Cost and accessibility: Many innovative drug delivery systems have high development and production costs, which limit their widespread usage.
Regulatory hurdles: Regulatory agencies’ Approval of advanced DDA involves complex, time-consuming, and expensive clerical work.
Conclusion
Advanced drug delivery systems (ADDS) are the latest medical innovations that provide promising solutions to many treatment challenges. These new techniques can transform patient care through enhanced efficacy, safety, and medical therapy compliance. However, substantial technical, economic, and regulatory challenges limit the widespread use of advanced DDS. To overcome these limitations, continued research and development are needed in this field, which will one day make these delivery methods accessible to a broader population, eventually revolutionizing our future healthcare systems.
Reference
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3. Kumar, S., Dilbaghi, N., Saharan, R., & Bhanjana, G. (2014). Nanotechnology as emerging tool for enhancing solubility of poorly water-soluble drugs. Bionanoscience, 4(4), 327-340. https://doi.org/10.1007/s12668-014-0150-3
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