Biomaterials for Drug Delivery Flashcards
What is the definition of a drug delivery system
A formulation or device that enables the introduction of a therapeutic substance in the body and improves its efficacy and safety by controlling the rate, time and place of release in the body
What 3 divisions does drug delivery encompass?
- The administration of the therapeutic product (IV, injection, tablet)
- The transport of the active ingredient to the target tissue
- The release rate of the active therapeutic ingredient
Name a few microparticle drug delivery systems
- Micelles
- Solid Lipid nanoparticles
- Liposomes
- Niosomes
- Gold nanoparticles
Explain how nanoparticles effectively target cells and release their drug payload
1) NPs containing a drug payload are coated in specialised proteins and ligands to target specific cell receptors
2) The NPs bind to the target cells via membrane proteins
3) This binding triggers the cell to ingest the NP
4) Enzymatic ingestion of the NP causes the drug to be released
Name a few brain related disorders
- ALS
- Alzheimer’s
- Stroke
- Migraine
- Vertigo
- Lipid Storage Disease (LSD)
What is Alzheimer’s caused by?
The clustering of amyloidal Beta proteins in the brain
How can Alzheimer’s be treated using nanoparticles
Gold nanoparticles
- Gold nanoparticles modified to target specifically amyloidal beta proteins
- These gold NPs bind to the clustered proteins in the brain and are irradiated using microwaves
- This causes the NPs to heat up and destroy the proteins, dissipating the aggregate
How have cancerous brain tumours been treated using nanoparticles?
Ferromagnetic Nanoparticles
- Ferromagnetic nanoparticles (made of iron oxide in a CaO-SiO2 matrix) are injected into the target cancerous tissue
- An alternating electromagnetic field is fed through the target tissue causing the particles to heat up killing the cancer cells
- Cancerous cells are destroyed at 43 degrees while regular cells can withstand heats to 48 degrees
Explain how Micelles have been used to target brain disorders?
Micelles are considerably smaller than most micro and nano particles.
Therefore they are able to carry a drug payload across the BBB to specific target cells
List the different drug release profiles
- Immediate (injection)
- Delayed
- Prolonged (microparticles)
- Extended (same as prolonged)
- Repeated (Capsules containing lots of microparticles)
- Controlled (insulin pumps)
What are some considerations to evaluate when optimising drug delivery?
- The drug release profile (how long and when)
- The administration route to reach target tissue
- The mechanism by which it releases
- Reduction of Side effects
- Patient Compliance
Give another example of a drug release mechanism that uses tungsten
Tungsten loaded hydrogels
- A calcium alginate microgel containing API and tungsten particles is administered
- Ultrasound waves are fed to the administration site. These waves cause the tungsten particles to vibrate, vibrating the microgel particles, mechanically shaking out the API
Explain how generic microgels offer a prolonged release profile
Microgels are hydrophilic hydrogel particles, which contain API embedded within their polymer mesh
When in contact with water the microgel absorbs it swelling and enabling the slow controlled release of drug
Explain how a prolonged release drug profile can be achieved through capsules and tablets
- Adding additional layers to slow degradation
Polymer coating the particles
Adding diluent to slow absorption
Changing concentration of particles in diluent
Particle and tablet size
How can controlled release of drugs be acheived?
Through devices that continuously feed drugs to the body such as IV fluids, Insulin pumps or buccal pumps
How are drugs administered nasally able to get past the BBB?
The olfactory epithelium is in direct contact with the olfactory nerve which is in direct contact with the brain, so drugs that interact with this nerve have direct access to the CNS
Describe the mechanism in the nasal space that defends against pathogens but also makes drug absorption harder
Mucociliary Clearance
This is a combined action of mucous producing goblet cells and cilia lined epithelial cells that line the respiratory tract
The mucous contains a protein called mucin that binds and traps inhaled particles, while cilia sweep the the mucus layer along the respiratory tract to swallow or cough out
Explain the process behind PLA, PLGA and PLG nanoparticle production (Double emulsion)
W/O/W Double Emulsion nanoparticle fabrication
1) Emulsify the dispersed aqueous drug solute phase with the continuous phase (polymer dissolved in acetone)
2) This creates the primary emulsion (W/O)
3) Emulsify the primary emulsion with another aqueous phase, homogenising the emulsion to get nanoparticles of uniform size
4) Evaporate the acetone, leaving polymer nanoparticles containing liquid drug
5) Freeze-dry the solution remove the water leaving polymer nanoparticles
Explain the production process of creating VB loaded PCL nanoparticles
W/O/W Double Emulsion
1) Emulsify the aqueous drug phase with the continuous PCL dissolved in methylene chloride phase
2) This produces the primary W/O emulsion
3) Emulsify and homogenise the primary phase with another aqueous phase (surfactant and water)
4) Heat the double emulsion to evaporate the lipophilic solvent, leaving a PCL coat
5) Centrifuge the solution to homogenise the nanoparticles
6) Freeze-dry the solution to remove aqueous phase leaving PCL nanoparticles loaded with VB
