Pharmacology Quiz: Drug Delivery Mechanisms

Nanotechnology and Applications in Medicine

• Nanotechnology is used in medicine.
• The presentation covers different methods to characterize nanoparticles.
• One technique is Dynamic Light Scattering (DLS).

Nanoparticle Characterization

• Methods exist to characterize nanoparticles' shape, size, and location.
• DLS measures fluctuations in scattered light intensity to determine particle size.
• This method is based on Brownian motion.
• Smaller particles show greater fluctuations than larger ones.

Brownian Motion

• Brownian motion is the random movement of small suspended particles in a fluid.
• The motion results from collisions of suspended particles with other fast-moving particles in the fluid.

UV-Vis Spectrophotometry

• UV-Vis Spectrophotometry is used for analysis.
• It measures optical density at different wavelengths.

Transmission Electron Microscopy (TEM)

• TEM enables direct 2-D imaging of particle size, shape, and surface characteristics.

Nanomedicine

• Nanomedicine is a field that involves the application of nanotechnology in medical treatments.
• It includes the use of nanodrugs.

Nanodrugs

• Nanodrugs are delivered in specific ways.
• Different delivery systems (nanocarriers) exist.
• Some systems are liposomes, solid lipid nanoparticles, and polymeric nanoparticles.

Types of Nanodrug Delivery Systems

• Liposomes are suitable for encapsulating hydrophilic and hydrophobic drugs to improve bioavailability.
• Solid lipid nanoparticles offer controlled release and stability for lipophilic drugs.
• Polymeric nanoparticles excel for loading drugs and targeted delivery, showing versatility in drug release profiles.

Liposomes

• Liposomes are spherical vesicles with at least one lipid bilayer.
• They are used as vehicles to deliver nutrients and pharmaceutical drugs.

Preparation of Liposomes (Thin-Film Hydration Method)

• This method involves several steps.
• It includes: solvent evaporation, hydration, liposomal formulation, sonication, and size reduction.
• The final product is liposomal suspension.

Types of Liposomes

• MLV (Multilamellar Vesicles): 1-5 μm
• LUV (Large Unilamellar Vesicles): 100-250 nm
• SUV (Small Unilamellar Vesicles): 20-100 nm

Polymers as Nanocarriers

• Polymers are the most commonly used nanocarriers.
• They are easily and cheaply fabricated in large quantities using various methods.
• Key properties in nanocarriers include chemical inertness, nontoxicity, and a lack of impurities.

Polymeric Nanoparticle Preparation Methods

• Nanoparticles can be prepared using methods like nanoprecipitation, solvent evaporation, and emulsion polymerization.

Nanoprecipitation

• This process is used for creating nanoparticles with controlled size and distribution and is ideal for encapsulating sensitive materials.
• It involves a precipitation step after organic solvent evaporation from the organic solution containing the polymer and drug solution.

Factors Affecting Bioavailability

• Factors impacting bioavailability of drug include low solubility, poor permeability, instability, and first-pass metabolism.
• Nanocarriers are helpful for improving the bioavailability of drug.

Mechanisms for Enhancing Bioavailability

• Nanoparticles can enhance bioavailability through several mechanisms.

Controlled Drug Release

• Nanodrugs can be designed to release their active components slowly over time to maintain therapeutic levels in the bloodstream for a longer period of time.
• This mechanism often is achieved through using biodegradable materials.

Sustained Drug Release Mechanism

• Some liposomes are made from biodegradable lipids that degrade over time.
• Encapsulated drug releases as the liposome structure breaks down.
• Certain liposomal formulations respond to external stimuli, such as changes in pH or temperature, triggering rapid drug release in specific conditions (e.g., acidic tumor environments).

In Vitro Drug Release Studies

• Studying in vitro release involves measuring the cumulative release over a specific time period.
• Different release profiles could include immediate, sustained, or prolonged release.