Lecture 21.5 - Polymeric Drug Delivery Devices Flashcards
1
Q
Enteral
A
- Intestinal (process through)
- All other routes considered parenteral
2
Q
Intravenous/Inraarterial
A
Parenteral
3
Q
Intramuscular/Subcutaneous
A
Parenteral
4
Q
Oral
A
Enteral
5
Q
Buccal/Sublinqual
A
- On cheek/under tongue
- Enteral
6
Q
Rectal
A
Enteral
7
Q
Nasal
A
Enteral
8
Q
Pulmonary
A
Parenteral
9
Q
Vaginal
A
Enteral
10
Q
Intrauterine
A
Enteral
11
Q
Transdermal
A
Enteral
12
Q
Oscular
A
Parenteral
13
Q
Half Life
A
- Many drugs have very short half lives
- Ampicillin (100 min)
- Penicillin (45 min)
14
Q
How to Maintain Drug Action?
A
- Requires significant concentration to remain effective
- Take repeated doses —> maintain activity by adding different doses of drug at different times
15
Q
Controlled Drug Delivery
A
- Better targeting (spatial targeting, temporal targeting)
- Reduce discomfort to patient (constant injections)
- Ability to reposition drug on the market (using different delivery system)
- Long lasting therapeutics
- Direct cell function in healing or forming tissues
16
Q
Spatial Targeting
A
Delivered to certain locations
17
Q
Temporal Targeting
A
Delivered in certain concentration at certain times
18
Q
Ideal Drug Delivery Systems
A
- Deliver drug at rate which matches need of body
- Deliver drug only to active site (cell, tissue, or organ)
- No drug delivery systems do both
19
Q
Common Systems/Release Rates
A
- Systems which provide “some” control of drug release in body (temporal, spatial, partial control of both)
- Prolonged or sustained release in systems are not controlled release systems by this definition (not spatially targeting, burst release where released over time)
20
Q
Sustain Drug Action
A
- Maintain constant effective drug level in body
- Avoid undesirable side effects of sawtooth kinetic profile
21
Q
Localize Drug Action
A
- Place drug delivery system in or next to diseased tissue or organ
- Ex: chemotherapeutic wafer (kill anything left behind)
22
Q
Target Drug Action to Specific Cell
A
- Carriers or chemical derivatization to target specific cells
- Only specific cells uptake drug and have action on it
23
Q
Factors that Influence Drug Delivery Rate: Drug
A
- Solubility (in polymer)
- Partition coefficient (how segregated within polymer)
- MW
- Chemical/physical stability
- Protein binding (probability/propensity)
24
Q
Factors that Influence Drug Delivery Rate: System
A
- Material solubility
- Swelling
- MW
- Crystallinity
- Physical stability (degradation)
- Protein binding
25
Polymeric Drug Delivery Systems
- Matrix ---> matrix of polymer with drug inside (more uniform distribution of drug within polymer)
- Reservoir
26
How are drugs eluted?
- Diffusion
| - Erosion
27
Degradable
- Diffusion and erosion
| - Aqueous solutions of body start to interact with polymer, polymer starts to swell
28
Non-degradable
Diffusion
29
Swollen Matrix
- More diffusion leads to swollen matrix
| - Smaller density of polymer chains
30
Non-swollen Matrix
Greater density of polymer chains
31
Factors Influencing Drug Release
- MW
- Crystallinity
- Swelling ratio
- Glass transition temperature
- Crosslink density
32
Factors Influencing Drug Release: Molecular Weight
- Amorphous polymer ---> decrease in MW, increase drug release
- Give chains motion, ends have more motion and more space in between
- More ends, greater diffusivity of drug through polymer chains
- More ends, greater release of drug into system
33
Factors Influencing Drug Release: Crystallinity
- Increase crystallinity, decrease release rate
| - Crystallinity decreases ability to diffuse (greatest diffusivity, fastest release rate)
34
Swelling Ratio
- How easily water is absorbed into polymer, affinity of polymer for water
- If polymer likes water (extremely hydrophilic) and structure flexible to accommodate water molecules, high swelling ratio
- If swelling, less dense (more free space), greater diffusivity of drug
- Increased swelling ratio, increased release rate
35
Glass Transition Temperature
- If T_g farther below body T, increased release rate
- Change in density at T_g (above T_g chains moving, below T_g very little motion)
- Decrease T_g, increased release rate
36
Crosslink Density
- Increase crosslinking, slow down degradation (if erosion slower release rate, if diffusion reduce chain motion/free space)
- Increase crosslink, decrease release rate
