Lecture 7 - Advanced Drug Delivery Systems Flashcards
Name the alternative routes of insulin delivery
Oral
Nasal
Buccal or Pulmonary
Subcutaneous
Transdermal
How can we increase the absorption of a drug?
Increase the contact time by adding mucoadhesives
Increase the permeability - surfactants
Open tight junctions - make space between cells bigger
Describe how reverse micelle formation increases absorption?
Sodium deoxycholate increases nasal insulin absorption - applicable to other epithelia
How to deliver proteins orally?
In nanocarriers - can be taken up by cells in the gut relatively easily
Protected from the harsh environment within the stomach and within GI tract
Via receptor-mediated transcytosis or via the paracellular pathway
Key Points for insulin - pulmonary delivery?
Small particle size
High SA
Wide range of drugs - proteins, peptides, mAbs vaccines, small molecules, anionic, cationic, hydrophilic, hydrophobic
Define Controlled Drug Delivery Systems (CDDS)
Preparations are designed in such a way that the release rate or location of active drugs Is controlled
Referred to as a modified release
Describe long term release
Implantable drug delivery systems usually polymer based
Slowly release drug over a long period of time - local or systemic
Release mechanism dependent on polymer characteristics
Define stenosis
Narrowing of a blood vessel
Issues with stents
Restenosis - reoccurrence of narrowing of the artery
How can we overcome restenosis in stents?
Drug-eluting stents
Prevents the regrowth of the cells in the surrounding tissue where the stent Is
What are Drug Eluting Stents composed of?
Polylactic acid backbone
Polylactic acid/everolimus coating
Stent bio absorbed in 2 years - due to bulk erosion - artery remains open
Vasomotion restored
Restenosis prevented - clinically safe
Describe responsive drug release
Drug release controlled by:
- pH
- chemicals
- enzymes
- ultrasound
- magnetism
- light
- electronics
Predominately used in implantable devices or parenterally delivered DDS= drug release when that particular stimulus is present
Whats the issues with responsive release of insulin?
Always wearing a device
Change the set every three days
Skin irritation/infection
Some poor skin insert sites
Peripheral insulin delivery
What is an alternative pump?
An implantable pump- goes under the skin and delivers insulin directly into the liver via a catheter. This is refilled every 3 months and can be controlled remotely
What are the disadvantages of the implantable insulin pump?
Big and bulky
If it fails and the patient doesn’t know is serious
Describe induced pluripotent stem cells
Patient-derived cells
Can potentially be grown in large numbers
No issues with rejection
Define tissue engineering
The idea that isolate rich and purified cells from patients usually stem cells. We grow them in the lab - loads to make a tissue - seeding on a suitable scaffold with all the necessary growth factors and chemicals they need in order to grow and survive and then differentiate into the type of cells we need and the implant in the patient
Describe how we can repair damaged vessels
Harder with larger vessels - need to withstand the high pressures required
Pulsatile culture produces vessels with increased strength and more extracellular metric deposition than static culture
Describe bioprinting
Taking cells in an ink and printing them in the right 3D structures to generate tissues
Valves and cardiac muscle can also be printed
Describe regneration
Promote healing by activation of body’s own cels and repair mechanisms
Define acellular scaffolds
Much more cost-effective than engineered tissues and cell-based therapies easier for clinicians
ideally minimally invasive
Great for damaged tissues not applicable for whole organs
