control drug delivery system an overview
DESCRIPTION
TRANSCRIPT
![Page 1: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/1.jpg)
Outline and Recommended Reading“Controlled Drug Delivery: Fundamentals and Applications”, (Drugs and the Pharmaceutical Sciences; v. 29). 2nd ed. Revised and Expanded, edited by J.R. Robinson and V.H.L. Lee 1987
1. ***Fundamentals and Practical Applications of Controlled Release Drug Delivery
2. Influence of drug properties and routes of drug administration on the design of sustained and controlled release technology
3. Theory of mass transfer4. Fundamental considerations in polymer science for
pharmaceutical application5. PK/PD basis of controlled drug delivery: dosing considerations
and bioavailability assessment6. Regulatory implications7. ***Design and fabrication of technology based controlled
release drug delivery systems8. Cases studies: oral, parenteral, implantable, transdermal,
micro/nano particulate colloidal carriers
![Page 2: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/2.jpg)
Release: 1987-01-30Publisher: Informa HealthCareFormat: Hardcover 744 pagesISBN: 0824775880
![Page 3: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/3.jpg)
Reasons for Interest…
• Drug re-positioning –patenting
• Biotherapeutics
• Better targeting• Better T.I. (therapeutic index, TD50/ED50)
– Precise spatial and temporal placement within body
![Page 4: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/4.jpg)
An Ideal Drug Delivery System
1. Release rate dictated by the needs of the body over the period of treatment
– Constant, 0-order (clear PKPD)– Variable (rhythm)
2. Channel the drug to the active site, cell, tissue, organ (drug targeting)
3.3. ““No such DDS exists which combines 1 No such DDS exists which combines 1 and 2…!!!”and 2…!!!”
![Page 5: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/5.jpg)
Terminology
• Systems which can provide “some” control of drug release in the body– Temporal – Spatial– Both– Specify release rate and
duration in vivo by simple in vitro tests
• Prolonged or sustained release systems are not controlled release systems by this definition
![Page 6: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/6.jpg)
Controlled Delivery Attempts to:
1. Sustain drug action at a predetermined rate by maintaining a relatively constant, effective drug level in the body with concomitant minimization of undesirable side effects associated with a sawtooth kinetic pattern
2. Localize drug action by spatial placement of a controlled release system (usually rate controlled) adjacent to or in the diseased tissue or organ
3. Target drug action by using carriers or chemical derivatization to deliver drugs to a particular “target” cell type
![Page 7: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/7.jpg)
Rationale of Controlled Drug Delivery• Alter PK/PD by:
– Design of drug delivery system– Modify drug structure– Modify physiology
• Duration of drug action is a design property of the rate controlled dosage form and not a property of the drug molecule’s inherent kinetic characteristics.
![Page 8: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/8.jpg)
Factors Influencing the Design and Performance of Controlled Release Dosage forms
1. Drug properties
2. Route of drug delivery
3. Target sites
4. Acute or chronic therapy
5. The disease
6. The patient
![Page 9: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/9.jpg)
Physicochemical Properties of a Drug Influencing Design and Performance
• Solubility
• Partition coefficient
• Molecular weight
• Chemical stability
• Physical stability
• Protein binding
![Page 10: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/10.jpg)
Biological Characteristics of a Drug Influencing Design and Performance
• ADME(T)– Duration of action– Safety
• Side effects
• Margin of safety
• Role of disease state
• Role of Circadian Rhythm
![Page 11: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/11.jpg)
Selected routes of Drug Administration
• Enteral – Intestinal– All other routes considered Parenteral
Is this enteral or parenteral drug delivery ? What type of injection is this ?
![Page 12: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/12.jpg)
Routes: (par-enteral?)
• Intravenous/intraarterial• Intramuscular/subcutaneous• Oral• Buccal / Sublingual• Rectal• Nasal• Pulmonary• Vaginal• Intrauterine• Transdermal• Ocular
P
EP
PP
P
PP
P
PP
![Page 13: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/13.jpg)
Necessary to dose at intervals shorter than ½ life?
1.T.I.~22.No physiological
constraints3.Delivery limited
![Page 14: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/14.jpg)
Can these drugs benefit from sustained release formulations?
![Page 15: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/15.jpg)
Duration of Action
![Page 16: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/16.jpg)
Theory of Mass Transfer
Fick's first law relates the diffusive flux to the concentration field, by postulating that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative). Fick's second law predicts how diffusion causes the concentration field to change with time.
![Page 17: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/17.jpg)
Diffusion is an Effective Transport Mechanism over Small Distances
![Page 18: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/18.jpg)
Passive Diffusion Through a Membrane: The Partition Coefficient
![Page 19: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/19.jpg)
Making/Fabricating Polymers…
![Page 20: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/20.jpg)
Chemical structures of polymers and copolymers used in product preparation
Current Drug Metabolism, 2007, 8, 91-107
![Page 21: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/21.jpg)
PK/PD basis of controlled drug delivery: dosing considerations and bioavailability assessment• Models of Drug Input and Elimination
– 0-order absorption followed by 1st-order elimination
– 1st-order absorption followed by 1st-order elimination
– Model independent PK analysis
• Pharmacodynamic Models– Fixed-effect model [drug] effect obs. or
n/obs.
![Page 22: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/22.jpg)
0-order release with a fast release component: rapid elimination
![Page 23: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/23.jpg)
0-order release with a fast release component: slow elimination
![Page 24: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/24.jpg)
1st-order release with a fast release component: slow elimination
![Page 25: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/25.jpg)
Increase and Reduce…
![Page 26: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/26.jpg)
Regulatory implications
• Demonstration of safety and efficacy– Already approved drugs
• Submitted data– Specifications meet claims made– No dose dumping– Steady state performance equivalent– Daily dose equivalent– Tight specifications (low variability)
• Recommended reference standard for comparative studies• Demonstration of product’s controlled release nature
– Biopharmaceutics/dissolution• Proper choice of apparatus• Sink conditions• Most discriminating variable knows, process critical• Complete release (>75-80%)
• In vivo bioavailability data
![Page 27: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/27.jpg)
Specific Example: Part 1
Hovik Gukasyan, PhD
![Page 28: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/28.jpg)
Drug Delivery to the Back of the Eye
• Subtenon– Injection behind the eye in
the subtenon space
• Intravitreal ( IVT)– Injection of a suspension
or device into the vitreous
• Topical– Solution/Suspension
dispensed to front of the eye ( exploratory)
Intravitreal device delivery
![Page 29: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/29.jpg)
Medidur Device with FA for DME
•TD sol = 15 g/mL (pH 7.4)•0.2 g/day•1000 day duration ~ 3 yr•Phase III – 3 yr study
OF
HOH
H
OOH
OO
200 g drug90% drug/10% PVA
FA = fluocinolone acetonidePD-0076535
25 gaugePVAPVA or Silicone seal
PolyimideTube
3.5 mm
OD=0.37 mm
Solubility is a main driver for release rate- most legacy VEGFRcompounds ( free bases)were not soluble enough
![Page 30: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/30.jpg)
10% PVA solution
![Page 31: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/31.jpg)
OH
nO
O
n m
Polyvinyl alcohol
Ethyl vinyl acetate
Ethyl cellulose
![Page 32: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/32.jpg)
Tube assembly and parts,prior to filling
![Page 33: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/33.jpg)
“wet granulation of FA” and filling the tubes…
![Page 34: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/34.jpg)
Filled tubes, cutting them to right dimensionsprior to applying seals
![Page 35: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/35.jpg)
Sealing
![Page 36: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/36.jpg)
Examples of what seals “should” look like visually
![Page 37: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/37.jpg)
Delivery device, “introducer”
![Page 38: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/38.jpg)
Impact of solubility in PBS/Vitreous
• Preferred solubility range 40-400g/mL
• Below 40g, explore formulation options to increase the rate of dissolution (implication on timelines)
• Above 400g, explore increasing PVA crystallinity
![Page 39: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/39.jpg)
20
40
60
80
100
120
140
PF-003
7140
4x
PF-005
2570
5a
PF-004
4685
9a
PF-003
3721
0
AG-028
588x
PF-002
3275
8a
PF-034
3130
5x
PF-000
8729
8x
PF-005
4730
9-14
x
PF-001
3864
7x
AG-028
613x
PF-001
3864
8x
PF-003
7375
8a
PF-004
4839
3ND
PF-006
0005
1-51
ND
PF-003
5758
2ND
g/m
L s
olu
bil
ity
buffer solubilityvitreous solubility
Experimental conditions•2-3mgs compound•2mL “solvent”•72hr incubation at 37°C•25 rotations/min•n=1-3, x : crystalline, a : amorphous, ND : solid state not determined
FA
TA
DEX
![Page 40: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/40.jpg)
![Page 41: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/41.jpg)
Change entire medium every 24hrsAnalyze by HPLC method8 day studyPlot cumulative drug released over time
cu
mu
lati
ve
dru
g r
ele
ase
d
time
“lag time”Linear p
ortion of c
urve = steady s
tate release ra
te
“Release” studies
![Page 42: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/42.jpg)
90% Active in 10% PVA “paste”
Ctot = Cs
Dire
ctio
n of
m
ass
tran
spor
t
10%PVA coat
Vitreous Humor(or sampling compartment)
CL
(or sampling)
Silicone adhesive seal (“low dose”configuration)
Blood flow
, systemic circulation clearance
![Page 43: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/43.jpg)
Photomicrographs of implants prepared by 'potting and slicing' of the tube to show drug matrix and the end caps. Process used involves an Al-mount which resulted in the sample becoming contaminated with aluminium particles ( the black bits in the photo).
PVA Endcap
PF337210
PF337210
PF337210
SU14813
![Page 44: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/44.jpg)
Polarized light to enhance the contrast for visualizing the end cap.
PVA Endcap
![Page 45: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/45.jpg)
Specific Example: Part 2
Hovik Gukasyan, PhD
![Page 46: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/46.jpg)
Q = amount of drug permeatedD = diffusion coefficientA = surface areaC = solubility of drugh = thickness of membranet = time
Assumptions:1. Diffusion
via H2O-filled pores
h = XYZ mm A = XYZ cm2
Functional Principles of Medidur® Technology
D = Q/A”C”t h
Release Rate/Diffusion
Dev
ice
Pro
per
ties
Compound Properties
![Page 47: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/47.jpg)
Diffusion Chamber & PVA Membrane
• PVA membrane fabrication• 10%w/v (aq). 78kDa 98% hydrolyzed
• “SOP”: 3 layers, air dried, cure at 135°C for 5 hours
• other formulation variables• # of layers can be 2• curing temp. range 100-180°C
• 1000l sample from 4mL chamber (25mM PB pH7.4 in saline, maintained at 37°C)
• CORRECT FOR AREA!!!
• Cr = Cn + (1 mL / 4 mL) x Cn-1
Papp = dC/dt * 1/CA = cm/sec
Diffusion coefficient isPapp * diffusion path length = cm2/sec
![Page 48: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/48.jpg)
Solubility (g/mL)25mM PB pH7.4 in saline, maintained at 37°C, crystalline material equilibrated for 72hrs
Es
tim
ate
d
g/d
ay
rel
eas
e f
rom
Me
did
ur®
5
10
15
20
25
30
35
40
45
0 5000 10000 15000 20000 25000 30000
CAI, PF4246518
NH
O
F
NH
O5FU
0.5
1
1.5
2
0 100 200 300 400 500
PF
19
04
40
PF
54
73
09P
F3
37
210
FA
PF
36
68
01
PF
52
04
61PF484286
Nevirapine
Linear fity=0.0026x+0.086R2=0.994includes 5FUexcludes CAI
Correlation of solubility to functional performance
![Page 49: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/49.jpg)
N
NH
NN
O PF520461
OCH3
O
O
CH3
CH3
OH
OH
F
CH3
F
O
HH
H
H
-9.5
-8.5
-7.5
-6.5
-5.5
-4.5
-2 -1 0 1 2 3 4 5
clogP or clogD at pH7.4 if ionizable
Lo
g P
app
NH
O
F
NH
O
PF190440
PF547309
PF366801
PF337210
PF484286
Nevirapine
PF4246518
5FU
FA
![Page 50: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/50.jpg)
NH
O
F
NH
O
Solubility 26mg/mLMW 130g/mol6.8g/min flux, obtained from steady state portion of curveusing a linear fit described by y=mx+b, R2=0.99
Example and validation compound, AVERAGE n=3 membranes
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
50 100 150 200 250Time (min)
Cu
mu
lati
ve m
g o
f 5F
U t
ran
sfer
red
ac
ross
PV
A m
emb
ran
e
Why ethyl vinyl acetate, EVA, membranes do not work?
![Page 51: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/51.jpg)
Model
0
0.2
0.4
0.6
0.8
1
1.2
1.4
50 100 150 200 250 300 350 400 450 500
Solubility (g/mL)
Pre
dic
ted
In V
itro
R
ele
as
e (g
/da
y)
0
0.5
1
1.5
2
2.5
Du
rati
on
(y
ea
rs)
*Release (g/day)
**Duration (years; f(x)=1/x type of functionwhere payload is 200g)
![Page 52: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/52.jpg)
Release Rate/Diffusion
Dev
ice
Pro
per
ties
Compound Properties
Membrane thickness¶
Curing temperature¶
Partition coefficient
Need to update equation?
D = Q/A¶”Ck”t h¶
![Page 53: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/53.jpg)
Assumptions
• Daily dose required for sufficient target tissue exposure and efficacy
• Well behaved release e.g. D = Q/ACt h• Diffusion coefficient theoretical:
– (1/f)*kT where f=6hr (calculated for a sphere is minimal value, asymmetry and nonelastic interaction with solvent)
– Dependent on size and shape of drug, interaction of drug with solvent and viscosity of solvent
• Diffusion coefficient calculated:– Q vs. t plot– Release rate study
![Page 54: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/54.jpg)
Solmax
Vitreous SpacePolyimid capillary tube shell
Collagen fibrils
Hyaluronan matrix
Po
lyv
iny
l alc
oh
ol
(PV
A) m
em
bra
ne
pH7.4, 37°C, H2O
Water filled pores, tortuous path
25 g
auge
![Page 55: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/55.jpg)
Anomalous Release of Drugs from Polymeric Matrices
![Page 56: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/56.jpg)
2 layers vs. 3 layers?
•Total 40 configurations•n=3 per config•2 cure sets•100°C (or lowest acceptable temp.) vs. 135°C •120 cores 2 curing temp.= 240 cores needed
Mapping Tunable Implant Parameters Per Compound
i.e. curing temperature, #of PVA/EVA coat layers, surface area of end caps
![Page 57: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/57.jpg)
No end cap Silicone seal
No end cap No end cap
Silicone seal
No end cap
No end cap
No end cap
25 gauge 18 gauge
Hig
h release
Lo
w
100°C (or lowest acceptable temp. must be determined using clear physical cutoff limits, i.e. %weight loss-polymer over time in release) vs. 135°C
Possible tox doses
Possible efficacious doses
2 layers
2 layers
2 layers
Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers
2 layers
2 layers
Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers
2 layers
2 layers
Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers
2 layers
2 layers
Silicone seal
3 layers 3 layers
3 layers Silicone seal
10% PVA coating 10% EVA coating
5% PVA coating 5% EVA coating
2 layers 2 layers
2 layers Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers 2 layers
2 layers Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers 2 layers
2 layers Silicone seal
3 layers 3 layers
3 layers Silicone seal
2 layers 2 layers
2 layers Silicone seal
3 layers 3 layers
3 layers Silicone seal
10% PVA coating 10% EVA coating
5% PVA coating 5% EVA coating2 layers
3 layers
2 layers
3 layers
2 layers
3 layers
2 layers
3 layers
EVA coats
![Page 58: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/58.jpg)
Polymeric Drug Delivery SystemsPolymeric Drug Delivery Systems
Hovik Gukasyan, Ph.D.
I.Polymer TypesII.Factors Influencing Drug
ReleaseIII.Systems
1.Matrix2.Reservoir
IV.Degradable Polymers
![Page 59: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/59.jpg)
TypeType
Rel
ease
Rat
e
Time
Polymer-Based Approaches to Control Drug ReleasePolymer-Based Approaches to Control Drug Release
![Page 60: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/60.jpg)
Polymer Type Examples Drug TypeHydrophilic
Biodegradable
Swellable
Bioadhesive
Ion-exchange
Hydrophobic
Poly(2-hydroxyethyl methacrylate)
Poly(vinyl pyrrolidone)Poly(lactic acid)Poly(glycolic acid)Collagen
Ethylene/Vinyl Alcohol
PolycarbophilFibronectin segment
Polystyrene sulfonic acid
PolydimethylsiloxanePolyethyleneEthylene/Vinyl acetatePolyurethane
Lipophilic and Hydrophilic
Lipophilic
3
![Page 61: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/61.jpg)
HydrogelsHydrogels
Natural -- Collagen Cellulose Cross-linked dextrans
Synthetic -- Poly(alkyl methacrylates)
4
![Page 62: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/62.jpg)
![Page 63: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/63.jpg)
Sp
Mesh size, Sp of macrmolecular network. Crosslinks (o) may bephysical entanglements or chemical, permanent junctions. Spheresrepresent the available space for drug diffusion between chains.
6
![Page 64: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/64.jpg)
Incr
emen
t of
Wat
er U
pta
ke
(%)
60
40
20
Hours
5 10 15 20
Fraction
of Dru
g Released
(F)
0.4
0.2
2:1 MEEMA-HEMA(9.1% w/w)
water uptakefraction released
7
![Page 65: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/65.jpg)
Factors Influencing Drug Release from Factors Influencing Drug Release from PolymersPolymers
Diffusingmolecule
polymerchains
polymerchains
(a) Symmetrical model
(b) Unsymmetrical model
8
![Page 66: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/66.jpg)
![Page 67: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/67.jpg)
Factors Influencing Drug ReleaseFactors Influencing Drug Release1. Molecular Weight
20
40
60
80
100
Avg
. cum
ulat
ive
%ag
e W
R-7
557
rele
ase
in v
itro
0 10 30 40 50 60 70 80 9020
Time (days)
150 000 Molecualr Weight
210 000 Molecular Weight
450 000 Molecular Weight
10
![Page 68: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/68.jpg)
2. 2. CrystallinityCrystallinity
Change in the Crystallinity of Poly(-Caprolactone) as a
Function of Molecular Weight
MolecularWeight (Mw)
59,30053,00046,40037,10030,60026,80023,40021,700
Crystallinity(%)
47.550.650.552.557.058.658.459.5
11
2. 2. CrystallinityCrystallinity
Change in the Crystallinity of Poly(-Caprolactone) as a
Function of Molecular Weight
MolecularWeight (Mw)
59,30053,00046,40037,10030,60026,80023,40021,700
Crystallinity(%)
47.550.650.552.557.058.658.459.5
11
![Page 69: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/69.jpg)
%CrystallinityPolymer
Poly(L-lactic acid)Poly(DL-lactic acid)Poly(Glycolic acid)
37%0%
50%
12
![Page 70: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/70.jpg)
0.83
0.84
0.85V
/(10
-3 m
3 k
g-1)
-25 0 25 50T/°C
Tg(0.02)
Tg(100)
0.02h
100h
Polymer Tg (°C) SS Flux(1011 g/cm/s)
Poly(-caprolactone)Poly(DL-lactic acid)1:1 copolymer
-655727
6.10.00033
5.8
3. Glass Transition Temperature3. Glass Transition Temperature
13
![Page 71: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/71.jpg)
4. Cross4. Cross--Links DensityLinks Density
Dependence of in vitro and in vivo Release Profiles of Norgestomet and Polymer Diffusivities on Extent of Cross-Linkage (XL) in Hydrogel Implants
XL(%)
1.24.89.6
12.014.416.819.2
Dp x 103
(cm2/day
97.224.212.19.78.16.96.1
Q/t1/2 (mg cm-2 day -1/2)In vitro In vivoa
0.6050.3960.1850.1330.1010.0740.058
0.6400.504--------------------
0.129
aResults from the subcutaneous implantation of Norgestomet-releasing Hydrogen implants in 39 cows for 16 days
14
4. Cross4. Cross--Links DensityLinks Density
Dependence of in vitro and in vivo Release Profiles of Norgestomet and Polymer Diffusivities on Extent of Cross-Linkage (XL) in Hydrogel Implants
XL(%)
1.24.89.6
12.014.416.819.2
Dp x 103
(cm2/day
97.224.212.19.78.16.96.1
Q/t1/2 (mg cm-2 day -1/2)In vitro In vivoa
Q/t1/2 (mg cm-2 day -1/2)In vitro In vivoa
0.6050.3960.1850.1330.1010.0740.058
0.6400.504--------------------
0.129
aResults from the subcutaneous implantation of Norgestomet-releasing Hydrogen implants in 39 cows for 16 days
14
![Page 72: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/72.jpg)
TIME
INT
EN
SIT
Y5. Biocompatibility5. Biocompatibility
Acute ChronicHealing
PMN’s Fibroblasts
FibrosisMononuclear Leukocytes
15
![Page 73: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/73.jpg)
Placebo considerations…• NCE (physicochemical properties, SAR, in vitro
assays) or a new formulation containing new excipients or vehicles.
• Medidur®/Retisert®/Vitrasert®– FDA provides most current and thorough look at
(non)clinical development of a nonbiodegradable ocular implants. Toxicologic Pathology, 36:49-62, 2008Toxicologic Pathology, 36:49-62, 2008
– Technology utilizes polyimid and polyvinyl alcohol polymers, both of which have ocular clinical use precedence.
– In ~1000 patients (some with multiple implants), PHIII clinical trial.
![Page 74: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/74.jpg)
Biocompatibility study of extracts from empty implants (available?) Procedure related
trauma. Eye large enough to perform accurate injections.
Offer delivery options; via other
route-configurations.
Volume displaced by core as a ratio of total volume of vitreous of
species selected.
Repeat injections: of similar or increasing “dose” vs. insertion
by incision more invasive
Reliably detect and insert implants through narrow
anatomy. Direct core at a more acute angle
after penetration
Core is not tethered can move around and/or settle
Compound specific response: need an n-
number of control compounds with
characterized pharmacological
profiles (on and off target)
Immune response (sudden severe)
and/or macrophage infiltration as a result
of foreign body presence (i.e. core)
not drug – “eye reacts as it should”
Incidental or spontaneous
changes that can result in
histopathological observations
Placebo design & formulation
Toxicologic Pathology, 36:49-62, 2008Toxicologic Pathology, 36:49-62, 2008
![Page 75: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/75.jpg)
Placebo Proposals
MATCH• Size• Material• Number• Delivery
Configuration Silicone sealSilicone seal
XYZ layersXYZ layers
1
2
3
![Page 76: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/76.jpg)
Animal Species
RatHamsterGuinea Pig
Capsule
ThickThinThin
Thickness, mm
0.16 - 0.250.05 - 0.050.03 - 0.06
Species differences in the development of the fibrouscapsule surrounding poly(2-hydroxyethyl methylcrylate)implants
16
![Page 77: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/77.jpg)
Matrix Matrix SytstemsSytstems (Monolithic(MonolithicSystems)Systems)
t=t1 t=t2
Cs
t=t3
Cylindrical DevicesCylindrical Devices
Drug release is described by Fick’s Law
Cs
t=t1
Cs
t=t2
Cs
t=t3
}
l}
l
}
l
17
Matrix Matrix SytstemsSytstems (Monolithic(MonolithicSystems)Systems)
t=t1 t=t2
Cs
t=t3t=t1t=t1 t=t2t=t2
Cs
t=t3
CsCsCs
t=t3
Cylindrical DevicesCylindrical Devices
Drug release is described by Fick’s LawDrug release is described by Fick’s Law
Cs
t=t1
Cs
t=t2
Cs
t=t3
}
l}
l
}
l
Cs
t=t1
Cs
t=t2
Cs
t=t3
Cs
t=t1
CsCsCs
t=t1
Cs
t=t2
CsCs
t=t2
Cs
t=t3
CsCsCs
t=t3
}
l}
l
}
l
}
l}
l
}
l
17
![Page 78: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/78.jpg)
Constraint
CO > CS
CO >> CS
Mt
A[DCS(2CO-CS)t)]1/2
A(2DCSCOt)1/2
dMt/dt
(A/2)[(DCS/t)(2CO-CS)]
(A/2)[2DCSCO/t]1/2
Drug Loading
Dru
g re
leas
ed (m
g/cm
2 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2018161412108642
(Hours)1/2
18
Constraint
CO > CS
CO >> CS
Mt
A[DCS(2CO-CS)t)]1/2
A(2DCSCOt)1/2
dMt/dt
(A/2)[(DCS/t)(2CO-CS)]
(A/2)[2DCSCO/t]1/2
Constraint
CO > CS
CO >> CS
Mt
A[DCS(2CO-CS)t)]1/2
A(2DCSCOt)1/2
dMt/dt
(A/2)[(DCS/t)(2CO-CS)]
(A/2)[2DCSCO/t]1/2
Constraint
CO > CS
CO >> CS
Constraint
CO > CS
CO >> CS
Mt
A[DCS(2CO-CS)t)]1/2
A(2DCSCOt)1/2
Mt
A[DCS(2CO-CS)t)]1/2
A(2DCSCOt)1/2
dMt/dt
(A/2)[(DCS/t)(2CO-CS)]
(A/2)[2DCSCO/t]1/2
dMt/dt
(A/2)[(DCS/t)(2CO-CS)]
(A/2)[2DCSCO/t]1/2
Drug Loading
Dru
g re
leas
ed (m
g/cm
2 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2018161412108642
(Hours)1/2
Drug LoadingDrug Loading
Dru
g re
leas
ed (m
g/cm
2 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0D
rug
rele
ased
(mg/
cm2 )
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2018161412108642
(Hours)1/2
2018161412108642 2018161412108642
(Hours)1/2
18
![Page 79: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/79.jpg)
Geometry - Sector and HemisphereGeometry - Sector and Hemisphere
19
![Page 80: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/80.jpg)
ai
ao
R
ai
Top Viewt=0
Side ViewCross Section
t=0
Slice, Side ViewCross Section
t=0
20
aiai
ao
R
ai
Top Viewt=0
Side ViewCross Section
t=0
Slice, Side ViewCross Section
t=0
20
![Page 81: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/81.jpg)
24
16
8
0 40 80 120 160 200 240Am
ou
nt
Rele
ased
(m
g)
Time (hour)
Release of stearic acid into methanol from a cylindrical sector
21
![Page 82: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/82.jpg)
10 20 30 40 50 600
20
40
60
80C
um
mu
lati
ve %
Rele
ase
Time (days)
Schematic diagram of an inwardly-releasing hemisphere
22
![Page 83: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/83.jpg)
Mt
TimetL=l2
6DtB=
l2
3D
Mt DCo
l(t
l2
6D)
Mt DCo
l(t
l2
3D)
Reservoir SystemReservoir System
23
.. ..
.
.
...
....
.
![Page 84: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/84.jpg)
Q (m
g/cm
2 )
0 5
Time (hours)
10 15 20 25
2
4
6
8
10
12
14A B
C
D
0.15mm
0.60
1.0
2.5
24
Q (m
g/cm
2 )
0 5
Time (hours)
10 15 20 25
2
4
6
8
10
12
14A B
C
D
0.15mm
0.60
1.0
2.5
24
![Page 85: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/85.jpg)
Membrane
Core
Ring5.7
mm
13.4 mm
Transparent rate-controlling membranes
Pilocarpinereservoir
Annular ring(surroundsreservoir -
opaque whitefor visibility inhandling and
inserting system)
Schematic diagram of an ocular therapeutic systemSchematic diagram of an ocular therapeutic system
OcusertOcusert®® continuous drug delivery devicecontinuous drug delivery device
25
Membrane
Core
Ring5.7
mm
13.4 mm
Membrane
Core
Ring
Membrane
Core
Ring5.7
mm
13.4 mm
Transparent rate-controlling membranes
Pilocarpinereservoir
Annular ring(surroundsreservoir -
opaque whitefor visibility inhandling and
inserting system)
Schematic diagram of an ocular therapeutic systemSchematic diagram of an ocular therapeutic system
OcusertOcusert®® continuous drug delivery devicecontinuous drug delivery device
25
tems
s
![Page 86: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/86.jpg)
Time (days)
Pilocarp
ine R
ele
ase R
ate
(µ
g/h
r)100
80
60
40
20
0 1 2 3 4 5 6 7
PILO-40
PILO-20
26
![Page 87: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/87.jpg)
2. Progestasert2. Progestasert
Platform
Progesterone in reservoirwith BaSO4 and silicone oil
Rate-controlling polymericmembrane and entry portal
Therapeutic program: 65µg/dayprogesterone for one year 27
![Page 88: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/88.jpg)
100
80
60
40
20
0 50 100 150 200 250 300 350 400 450
Time (day)
Rele
ase R
ate
(µ
g/d
ay)
Comparison of in vitro and in vivo release rates from the Progesterate® system
28
![Page 89: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/89.jpg)
Covering membrane
Drug reservoir
Micropore membranecontrolling drug release
Adhesive contact surface
Surface of skin
Drug moleculesCapillary
9.5 - 14.3 mm
0.1
7 m
m3. Transdermal System3. Transdermal System
29
![Page 90: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/90.jpg)
xx x
x x
C
O OR
C
O OH
C
O OR
C
O O-
x
x x
x
x x
x
x x
x
Type I
Type II
Type III
Biodegradable PolymersBiodegradable Polymers
30
xx x
x x
C
O OR
C
O OH
C
O OR
C
O O-
x
x x
x
x x
x
x x
x
Type I
Type II
Type III
xx x
x x
xx x
x x
xx x
x x
C
O OR
C
O OH
C
O OR
C
O O-
C
O OR
C
O OH
C
O OR
C
O OR
C
O OH
C
O OH
C
O OR
C
O O-
C
O OR
C
O OR
C
O O-
C
O O-
x
x x
x
x x
x
x x
xx
x x
x
x x
x
x x
x
x x
x
x x
xx
x x
x
Type I
Type II
Type III
Biodegradable PolymersBiodegradable Polymers
30
H2O solubleSwellingDimensional stability
H2O insolubleChemical changeNo backbone cleavage
H2O insolubleChemical cleavageMW↓
![Page 91: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/91.jpg)
Rate of polymer dissolution and the rate of release of hydrocortisone for the n-butyl half-ester of methyl vinyl ether-maleic anhydride copolymer containing 10 wt% drug dispersion.
010 20 30 40 50 60
20
40
60
80
100
0
20
40
60
80
100
0Time (hours)
Dru
g r
ele
ased
(%
)P
oly
mer e
rod
ed
(%)C4 ester
Drug release
Polymer dissolution
31
![Page 92: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/92.jpg)
Erosion + Diffusion
Diffusion
0 1 2 3 4 5
15
10
5
Time
Dru
g r
ele
ased
32
![Page 93: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/93.jpg)
0 10 20 30 40 50 60 70 80 90
10
20
30
40
50
45
46
47
48
49
50
51
Days
Dru
g r
ele
ase r
ate
, µ
g/d
ay/c
mC
rysta
llinity
, %
polymer crytsallinity
drug release rate
33
![Page 94: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/94.jpg)
Osmotic deliveryorifice
Semi-permeablemembrane
Osmotic corecontaining drug
Osmotic Osmotic PumpsPumps
34
![Page 95: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/95.jpg)
0 1 2 3 4 5 6 7
10
20
30
40Stirring StirringNo Stirring
Hours
Delivery
rate
, m
g/h
r
AttributesAttributes
35
![Page 96: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/96.jpg)
0 1 2 3 4 5 6
10
20
30
40
Hours
Delivery
rate
, m
g/h
rTime in gastric fluidTime in intestinal fluid
15 percent oftotal delivered
36
![Page 97: Control drug delivery system an overview](https://reader038.vdocuments.net/reader038/viewer/2022103013/5454ec31af795997708b5c12/html5/thumbnails/97.jpg)
0 2 4 6 8 10 120
5
10
15
20
25GITS-AGITS-B
Indomethacin caps (25mg at 0, 4, 8, 12 hours)Indomethacin caps 3 x 25 mg
Time (hours)
Am
ou
nt
of
ind
om
eth
acin
pre
sen
t in
th
e b
od
y (
mg
)
37
IndocidIndocid