Other Drug Delivery Technologies V

Question 1

Parenteral delivery - adv and disadv

Answer 1

• Most biotherapies and vaccines injected using hypodermic needle

• Advantages
– Low cost
– Rapid delivery
– Deliver almost all molecules

• Disadvantages
– Cannot be used by patients themselves
– Specialised training required
– Safe needle disposal
– Patient compliance (pain/needle phobia)

Question 2

Oral delivery

Answer 2

• Overcomes problems associated with parenteral systems
– Convenient
– Pain free
– Self administration
• However, not suitable for all drugs
– First pass
– Reduced bioavailability

Question 3

Microneedles

Answer 3

• Shrinking of needle diameter into micron range
• Keeps advantages of delivery capacity
• Improved patient compliance and safety

Question 4

• Microneedle device requirements:

Answer 4

– Large enough to deliver almost any drug /particulate
– Small enough to avoid pain / fear
– Small enough to avoid need to specific expertise or training
– Specific delivery to localised area ie. Skin, eye, cell nucleus etc

Question 5

Delivery using microneedles

Answer 5

– Insulin
– DNA vaccines
– Protein vaccines
– Naltrexone
– Photodyanamic therapy agents
– Phenylephrine
– Acne medication

Question 6

Microbubbles

Answer 6

• Non invasive delivery system
• Traditionally used as contrast agents for diagnostic ultrasound
• Potential in drug delivery

Question 7

Drug incorporation into microbubble

Answer 7

• Binding of drug to microbubble shell

* Attachment at site specific ligands

Question 8

Delivery using microbubbles

Answer 8

• Using either breakdown of bubble and subsequent
uptake
• Or sonoporation: the use of ultrasound to modify
permeability of cell plasma membrane

• Reported:
– Plasmids
– Adenoviruses
– Chemotherapeutics

Question 9

Electroporation

Answer 9

• Physical transfection method using an electrical pulse to create temporary pores in cell membranes allowing
compounds to pass through

Question 10

Hydrogels

Answer 10

• Polymer networks extensively swollen with water – but not dissolved
• Networks of polymer chains cross-linked
• Possess degree of flexibility close to body tissue due to large water content
• Ability to hold water due to high degree of hydrophilic functional groups
• Cross-links however, hinder ability to dissolve

Question 11

Classification of Hydrogels

Answer 11

• Classified according to
– Synthetic or natural
– Polymer composition
• Homopolymeric
• Copolymeric
• Multipolymer Interpenetrating
– Physical state
• Amorphous
• Semicrystalline (complex mixture of amorphous and crystalline)
• Crystalline
– Charge
• Ionic
• Non-ionic
• Zwitterionic

Question 12

Formation of hydrogels

Answer 12

• Linking polymer chains via chemical reaction
• Using ionizing radiation
• Physical interaction such as electrostatic, crystal formation etc

Question 13

Transition of hydrogels

Answer 13

• Extent of swelling or de-swelling in response to the changes in external environments – resulting in volume or phase transition

Question 14

Hydrogels for drug delivery

Answer 14

• High water content results in relatively rapid release of drugs from gel matrix over hours or days
• Shorter release rate of hydrophilic drugs
• Strategies to reduce drug release from gel:
• Drug-hydrogel interaction
– Both physical and chemical strategies can be employed to enhance the binding between a loaded drug and hydrogel matrix to extend the duration of drug release
• Physical interaction
– Exploiting charge interaction
• Covalent bonding
• Gel network engineering
• Interpenetrating polymer networks

Question 15

Scaffolds

Answer 15

• Highly porous scaffold biomaterials
• Act as templates for tissue engineering
• Guide growth of new tissue
• Can also be exploited in drug delivery

Question 16

Types of polymeric scaffolds

Answer 16

• 3 dimensional porous matrix
• Nanofibrous matrix
• Thermosensitive sol-gel matrix
• Porous microsphere

Question 17

Drug incorporation into scaffold

Answer 17

• Physically incorporated into pores
• Physically incorporated into integral structure
• Physically coating scaffold structure
• Chemical conjugated into pores
• Chemically conjugated onto surface

Question 18

Remotely Triggered Scaffolds for Controlled - Release of Pharmaceuticals

Answer 18

• Biodegradable scaffolds that collapse after a fixed time
period, either naturally or after external stimulus, are
advantageous for long term use, e.g., to support tissue
development or act as slow drug release carriers.
• Addition of nanoparticles into the intrinsic
• Structure of a scaffold can enhance functionality and
lead to exciting new properties such as ability to
• Remotely trigger structural collapse which could
ultimately lead to drug release.