Drug Delivery Systems

1
Drug Delivery Systems
2
Definition drug delivery systems

• Biomaterials used to release drugs in the body,
  in a controlled manner.
• Control of timing and target.

http//www.devicelink.com/mpb/archive/97/11/9711b3
4b.jpg
3

• Conventional Drug Delivery Systems
• tablets, capsules, pills, suppositories, creams,
  ointments, liquids, aerosols, and injectables

From Chien, Novel Drug Delivery Systems. pg 2.
4
Polymeric DDSs

• Polymeric matrix incorporates drug
• Known release rate over prolonged duration
• Release to target (site of action)
• Goal constant release
• Target concentration in tissue depends on tissue
  absorption, drug kinetics, etc
• Drug protection when in situ (particularly for
  longer release periods)

5
DDS types

• Monolithic devices matrix systems
• Reservoir devices rate controlling membranes
• Degradable systems polymers degrade due to
  chemical action

6
DDS types, again
From Shi, Biomedical Devices and their
Applications, 2004
7
Diffusion in monolithic and reservoir devices
http//www.devicelink.com/mpb/archive/97/11/003.ht
ml
8
What happens after delivery?
http//www.devicelink.com/mpb/archive/97/11/003.ht
ml
9
Use Ficks law to design drug release
10
Rate control
11
smart materials, mechanism of action
http//www.devicelink.com/mpb/archive/97/11/003.ht
ml
12
Biodegradable systems
Figure 7. Drug delivery from (a) bulk-eroding and
(b) surface-eroding biodegradable systems
http//www.devicelink.com/mpb/archive/97/11/003.ht
ml
13
Biodegradable PLA and PEG
PLA poly(lactic) acid
14
PLGA (poly lactic-co-glycolic acid) and
polyorthoester
Biodegradable microparticles of 6040
lactideglycolide PLGA. (Photo courtesy of T.
Tice, Southern Research Institute, Birmingham,
AL.)
Biodegradable microparticle of 7525
lactideglycolide PLGA after 133 days of
degradation in water.
Biodegradable polyorthoester rods after (left) 9
and (right) 16 weeks of implantation in rabbits.
(Photos courtesy of H. Heller, Advanced Polymer
Systems, Redwood City, CA.)
15
Elementary osmotic pump
Pressure-controlled release. Pressure increases
due to osmosis.
http//www.uweb.engr.washington.edu/research/tutor
ials/drugdelivery.html
16
Extra salt layer two compartment pump
17
Alza Duros pump
http//www.alza.com/alza/duros
18
Two-compartment osmotic (commercial) pump
19
Diabetes
From Chien, Novel Drug Delivery Systems. Figure
30, pg 35.
20
Ocusert, pilocarpine to glaucoma patients
From Chien, Novel Drug Delivery Systems. Figure
1, pg 260.
21
Transdermal delivery (patches)
Cleary GW, "Transdermal Delivery Systems A
Medical Rationale," in Topical Drug
Bioavailability, Bioequivalence, and Penetration,
Shah VP, and Maibach HI (eds), New York, Plenum,
pp 1768, 1993.
22
Smart materials designed based on external cues
http//www.devicelink.com/mpb/archive/97/11/003.ht
ml