lec30_Nano delivery systems (I)
Nano-based Drug Delivery Systems
Introduction
Focus: Nano-based systems for drug delivery, size range 1 nm to 100 nm, with an upper limit often set at 1000 nm.
Importance: Unique properties enable targeted and controlled drug release.
Materials: Includes polymers, lipids, metals, and ceramics.
Learning Objectives
Definition of pharmaceutical nanotechnology.
Identification of different types of nano-based drug delivery systems.
Explanation of advantages of these systems.
Understanding of phospholipid structure and liposomes.
Benefits of liposome formulation.
Comprehension of the Enhanced Permeability and Retention (EPR) effect.
What is Nanotechnology?
Definition: Refers to pharmaceutical materials and structures around 1 nm to 100 nm.
Application: Focus on targeted and controlled release properties.
Conversion: Various materials can construct nano-delivery systems.
Advantages of Nano Delivery Systems
Targeted Delivery:
Design tailored to specify delivery to cells/tissues.
Reduces side effects by focusing delivery.
Controlled Release:
Engineered for sustained release, minimizing dosing frequency.
Enhanced Solubility:
Improves bioavailability of poorly soluble drugs by encapsulation.
Protection of Drugs:
Shields drugs from enzymatic degradation, enhancing stability.
Enhanced Permeability and Retention (EPR)
EPR Effect:
Larger molecules accumulate more in tumors than normal tissues due to tumor vascularity.
Tumor Growth: Induces abnormal angiogenesis for nutrition and oxygen.
Result: Poorly organized new vessels lead to leakage of blood components into tumor tissue.
Types of Nano Delivery Systems
Lipid-based Nanoparticles:
Composed of lipid bilayers; can encapsulate various drugs.
Polymeric Nanoparticles:
Made from biocompatible polymers designed for specific release kinetics.
Metal Nanoparticles:
Unique functionalization properties for drug delivery and imaging.
Dendrimers:
Highly branched polymers for drug attachment either on surfaces or internally.
FDA Approved Nano-delivery System
Abraxane:
Paclitaxel albumin-bound formulation, approved on January 7, 2005.
No organic solvent enables higher dosage delivery quickly.
Taxol:
Conventional formulation requiring organic solvents, longer infusion times, and pre-medication for side effects.
Liposome
Structure: Small vesicle with lipid bilayer, ranging from 20 nm to 10 μm.
Classification: Based on the number of lamellae; can be unilamellar or multilamellar.
Function: Can modify surface for targeting or PEGylation, encapsulating both hydrophilic (aqueous core) and hydrophobic (lipid bilayer) drugs.
Liposome vs. Cell Membrane
Similarities: Liposome membrane composition resembles cell membranes, ensuring biocompatibility.
Non-toxicity: Low immunogenic response enhances safety in applications.
Phospholipids Structure
Comprised of:
Hydrophilic Head: Choline ion, phosphate group.
Hydrophobic Tails: Fatty acid chains.
Liposome vs. Micelle
Micelle: Single-chain amphiphilic structure, typically smaller.
Liposome: Double-chain amphiphilic structure offering larger vesicles with more complex applications.
Structures of Liposome and Micelle
Examples of each structure showcasing their formation in aqueous solutions.
Applications of Liposomes
Fields of Application:
Cosmetics, diagnostic imaging, and drug delivery for a variety of medicinal molecules.
Advantages of Liposomal Formulation
Characteristics:
Biocompatible, biodegradable, capable of encapsulating diverse drugs.
Prolonged drug release, enhanced protection against degradation, targeted delivery possibilities through surface modification.
References
Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems, 12th Ed. (2021).
Khan, A. et al. (2022). "Tablets and Capsules." In: Essentials of Industrial Pharmacy.
AULTON, M. E., TAYLOR, K. (2013). Aulton's Pharmaceutics: The Design and Manufacture of Medicines.