Lecture 7 - Advanced Drug Delivery Systems

Question 1

Name the alternative routes of insulin delivery

Answer 1

Oral
Nasal
Buccal or Pulmonary
Subcutaneous
Transdermal

Question 2

How can we increase the absorption of a drug?

Answer 2

Increase the contact time by adding mucoadhesives
Increase the permeability - surfactants
Open tight junctions - make space between cells bigger

Question 3

Describe how reverse micelle formation increases absorption?

Answer 3

Sodium deoxycholate increases nasal insulin absorption - applicable to other epithelia

Question 4

How to deliver proteins orally?

Answer 4

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

Question 5

Key Points for insulin - pulmonary delivery?

Answer 5

Small particle size
High SA
Wide range of drugs - proteins, peptides, mAbs vaccines, small molecules, anionic, cationic, hydrophilic, hydrophobic

Question 6

Define Controlled Drug Delivery Systems (CDDS)

Answer 6

Preparations are designed in such a way that the release rate or location of active drugs Is controlled
Referred to as a modified release

Question 7

Describe long term release

Answer 7

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

Question 8

Define stenosis

Answer 8

Narrowing of a blood vessel

Question 9

Issues with stents

Answer 9

Restenosis - reoccurrence of narrowing of the artery

Question 10

How can we overcome restenosis in stents?

Answer 10

Drug-eluting stents
Prevents the regrowth of the cells in the surrounding tissue where the stent Is

Question 11

What are Drug Eluting Stents composed of?

Answer 11

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

Question 12

Describe responsive drug release

Answer 12

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

Question 13

Whats the issues with responsive release of insulin?

Answer 13

Always wearing a device
Change the set every three days
Skin irritation/infection
Some poor skin insert sites
Peripheral insulin delivery

Question 14

What is an alternative pump?

Answer 14

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

Question 15

What are the disadvantages of the implantable insulin pump?

Answer 15

Big and bulky
If it fails and the patient doesn’t know is serious

Question 16

Describe induced pluripotent stem cells

Answer 16

Patient-derived cells
Can potentially be grown in large numbers
No issues with rejection

Question 17

Define tissue engineering

Answer 17

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

Question 18

Describe how we can repair damaged vessels

Answer 18

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

Question 19

Describe bioprinting

Answer 19

Taking cells in an ink and printing them in the right 3D structures to generate tissues
Valves and cardiac muscle can also be printed

Question 20

Describe regneration

Answer 20

Promote healing by activation of body’s own cels and repair mechanisms

Question 21

Define acellular scaffolds

Answer 21

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