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Nanoparticles for Drug Delivery
Suzie PunDept of Bioengineering, University of Washington
Frontiers in NanotechnologyMay 18, 2004
Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples : Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
Methods of Drug Delivery
• Oral Delivery
• Inhalation
• Transdermal
• Implantation
• Injection
Advantages of Nanoparticles for Drug Delivery
University of Illinois, Urbana-Champagne
Examples of Nanoparticles for Drug Delivery
Liposomal Amphoterin, sold by Gilead (Ambisome) and Enzon (Abelcet) ~$200 Million in Ambisome sales in 2003.
Gilead Sciences
• Amphotericin treats fungal and parasite infection
• Most commonly used in patients with depressed white blood cell count (cancer and chemotherapy patients, HIV-infected patients, elderly patients).
• Liposomal formulation is preferred because of decreased side effects and prolonged drug exposure (due to slow release)
Applications: Non-resistant cancers
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
•In hepatic metastases model, the reduction in number of metastases was greater with Dox-loaded nanospheres than free dox. (Why hepatic model?)•No special affinity for tumor tissue detected. Most nanospheres located within Kupffer cells. See proposed mechanism of action•Note that this approach reduces side effects and toxicity! Small molecules are distributed throughout the body.
Examples of Nanoparticles for Drug Delivery
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Applications: Intracellular Infections
Macrophages infected with Salmonella incubated with ampicillin-loaded PACA nanospheres
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Antibiotic-loaded nanospheres
Resistance of many microorganisms to antibiotics is often related to low uptake of antibiotics or reduced activity in acidic pH of lysosomes.
1. Ampicillin-loaded nanospheres for Listeriatreatment. Dramatic improvement over free drug; bacterial counts in liver reduced at least 20-fold.
2. Ampicillin-loaded nanospheres for Salmonella treatment. Drug alone – required 32 mg per mouse; with nanoparticle, only 0.8 mg ensured survival.
Examples of Nanoparticles for Drug Delivery Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples : Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
Drug Carrier Systems
from Polymeric Biomaterials (2002), 2nd Ed., Edited by S. Dumitriu
Monoclonal antibodies; second-generation carriers with targeted antibodies or other
ligandsCarriers able to recognize a specific target< 1 µmThird
Liposomes, nanoparticles, polymer drug carriers
Carriers that can be given by a general route able to transport a drug to the target
site< 1 µmSecond
Microspheres and microcapsules for chemoembolization
Able to release a drug at the target site but needing a particular type of administration> 1 µmFirst
ExamplesDefinitionSizeGeneration
Nanoparticles for Drug Delivery
• Metal-based nanoparticles
• Lipid-based nanoparticles
• Polymer-based nanoparticles
• Biological nanoparticles
Metal Nanoparticles for drug delivery Metal Nanoparticles
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Metal Nanoparticles
Note: direct tissue injection
Lipid-based nanoparticles for Drug Delivery
DOPE
DSPC
DOTAP
Lipid-based nanoparticles for Drug Delivery
Deliverables:
-Small molecules (Amphotericin B, Daunorubicin, Doxorubicin – all approved and marketed drug formulations) Gilead, Alza
-Viruses and bacteria (as vaccines) – in development
-Nucleic acids – in development
Lipid-based nanoparticles for Drug Delivery
Many formulation methods --1. Mixing lipids together in
organic solution. 2. Remove solvent by
evaporation3. Hydration with aqueous
solvent containing drug to form multilamellar vesicles
4. Sonication or extrusion are common methods to reduce the size of the liposomes
Avanti Polar Lipids
Lipid-based nanoparticles for Drug Delivery
Drug properties and Liposome association
Hydrophilic Retained in aqueous interior Slowly released over **may be difficult to get several hours-several dayshigh loading
Hydrophobic Inserted into hydrophobic Excellent retention interior of the liposome bilayer**can disrupt liposome at high concentrations
Intermediate Rapidly partition between Rapid release from liposomeslipid bilayer and aqueous but pH manipulation orphase formation of molecular
complexes can result in good retention
• Poly(alkylcyanoacrylates) used extensively for tissue adhesives for skin wounds and surgical glue (late 1960’s)
• Application as drug nanoparticulate carriers (1980s)
• For detailed review, see:
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Polymer-based nanoparticles for Drug Delivery
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Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Polymer-based nanoparticles for Drug Delivery
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Polymer-based nanoparticles for Drug Delivery
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Polymer-based nanoparticles for Drug Delivery
DEGRADATION OF NANOPARTICLESHydrolysis of ester bond; degradation products
(alkylalcohol and poly(cyanoacrylic acid) are eliminated by kidney filtration.
Vauthier, et al. Adv. Drug Del Rev v55:519-548 (2003)
Polymer-based nanoparticles for Drug Delivery
Biological nanoparticles --Viruses
Scientific AmericanStratagene, Inc.
From an excellent review by Thomas et al. (2003) Nature v4:346
Biological nanoparticles --Viruses
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Thomas et al. (2003) Nature v4:346
Biological nanoparticles --Viruses Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples : Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
Stability of Colloids in Physiological Environments
1. Attractive van der Waals forces and random Brownian motion cause particle flocculation
2. Stabilization of colloids by electrostatic stabilization (DLVO theory):-- Charged particles have a counter-ion layer. The charged surface and
counter-ion layer is called the “electrostatic double layer”. For homogenous colloid suspensions, this electrostatic double layer acts as a repulsive force between particles.
--The sum of the van der Waals force and the double layer repulsion force gives the DVLO interaction potential:
M. Nikolaides
-higher ionic strengths collapse this boundary layer
-at high salt concentration, no stable region
-physiologic salt concentration ~150 nm
Aggregation of Colloids
C
A
Stability of Colloids in Physiological Environments
water 150 mM salt
-- in intravenous delivery, this can be a major cause of toxicity
Stability of Colloids in Physiological Environments
3. Stabilization of colloids by steric stabilization:-- Add polymers to the surface of particles to prevent the particles from
coming in close proximity to each other. At these distances, there is not enough attractive force for flocculation to occur.
--Note that this phenomena is solvent dependent (affects the structure and interaction of the surface polymers)
Steric Stabilization Dispersion Stabilization
Steric Stabilization
Choi, et al. J Disp Sci Tech (2003) v24:415
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Steric Stabilization
Choi, et al. J Disp Sci Tech (2003) v24:415 Ogris et al. (1999) Gene Therapy 6:595 (1999).
Steric Stabilization
Liposome Stability Liposome Stability Optimization
•Chemical stability
•Reducing oxidation – addition of antioxidants, storage at low temperatures and pH 6.5•Removal of water – spray drying or lyophilization (but both have to occur under controlled and optimized conditions)
•Physical stability
•Electrostatic stabilization•Steric stabilization•Cream or hydrogel incorporation
Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples : Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
Mechanisms of Removal from Circulation
from Polymeric Biomaterials (2002), 2nd Ed., Edited by S. Dumitriu
• Fast removal from circulation-binding to cells, membranes, or plasma proteins-uptake by phagocytes (macrophages)-trapping in capillary bed (lungs)
• Renal clearance -size restriction for kidney glomerulus is ~30-35 kDa for polymers
(~20-30 nm)
• Extravasation-depends on the permeability of blood vessels-capillaries are thought to be more permissive to extravasation-note: for cancer applications this works to our advantage: EPR!
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Drug Carrier Systems: Influence of Physicochemical Properties
• Molecular weight-macromolecules smaller than renal threshold are rapidly eliminated -for larger, non-degradable molecules, excretion is useful to decrease toxicity.
• Charge-positively-charged macromolecules will interact with cells and membranes (remember the negatively charged proteoglycans?)-negatively charged macromolecules are picked up by macrophages such as Kupffer cells, that contain polyanion scavenger receptors on their surface.
• PEGylation-may increase circulation by reducing non-specific protein binding.
from Polymeric Biomaterials (2002), 2nd Ed., Edited by S. Dumitriu
Drug Carrier Systems: Influence of Physicochemical Properties
http://education.vetmed.vt.edu/curriculum/VM8054/Labs/Lab20/Examples/exkupff.htm
Kupffer Cells
Drug Carrier Systems: Influence of Physicochemical Properties
1000 nm
6000 nm500 nm
200 nm
10,000 nm
“+”-charged
“-”-charged
neutral
Ogris et al. (1999) Gene Therapy 6:595 (1999).
PEGylated
Non-PEGylated
Biodistribution of PEGylated Polymer-based Nanoparticles
Biodistribution of Lipid-based NanoparticlesPEGylation
Non-PEGylatedliposomes
PEGylatedliposomes
Why is there a dose-dependence?
Allen, TM and Stuart, DD. “Liposome Pharmacokinetics” In Liposomes Ed. Janoff, AS (2000)
Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
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Non-specific targeting: EPR Effect
• Tumors generally can’t grow beyond 2 mm in size without becomingangiogenic (attracting new capillaries) because difficulty in obtaining oxygen and nutrients.
• Tumors produce angiogenic factors to form new capillary structures.
• Tumors also need to recruit macromolecules from the blood stream to form a new extracellular matrix.
• Permeability-enhancing factors such as VEGF (vascular endothelial growth factor) are secreted to increase the permeability of the tumor blood vessels.
• This effect is called the “enhanced permeability and retention effect” (EPR)
from Polymeric Biomaterials (2002), 2nd Ed., Edited by S. Dumitriu
Non-specific Targeting
• Small Molecules– Galactose/Glucose/Mannose– Folate
• Peptides– RGD
• Proteins– Transferrin– Antibodies– LDLs
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endocytosis.html
Targeting Ligands Targeting
Choi, et al. J Disp Sci Tech (2003) v24:415
Targeting
Choi, et al. J Disp Sci Tech (2003) v24:415
Nanoparticles for Drug Delivery
• Introduction – Systemic Drug Delivery
• Nanoparticles
• Challenge 1: Stabilization• Challenge 2: Extended Circulation• Challenge 3: Targeting
• Examples : Liposomes for chemotherapeutic deliveryCyclodextrin particles for gene delivery
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Examples of Nanoparticles for Drug Delivery
DOXIL
Formulation
1. Doxorubicin-containing core
2. Lipid Bilayer membrane
3. PEG-coated surface
4. <100 nm
Examples of Nanoparticles for Drug Delivery
DOXIL Proposed Mechanism of Action
Examples of Nanoparticles for Drug Delivery
DOXIL Pharmacokinetics
Rats Dogs
Gabizon, et al. Pharm Res v10:703 (1993)
Examples of Nanoparticles for Drug Delivery
DOXIL Toxicity
•Mild white blood cell depression
•Skin toxicity (unique to Doxil) with full recovery. (Long distribution time?)
•Cardiac toxicity – insignificant up to 1500 mg/m2; Much lower toxicity than doxorubicin (lower peak plasma level; decrease availability to cardiac muscle)
•Hair loss – rare; only seen in ~6% of patients
•Mucositis – ulceration of oral mucosa. Dose-limiting toxicity
Examples of Nanoparticles for Drug Delivery
DOXIL Efficacy
TTP Plat Res = time-to-progression platinum resistant; TTP Plat Sens = time-to-progression platinum sensitive; OS = overall survival.
**p = .01.
*Expressed as percentage.
63.3 wks86.1 wks**OSPlat Sens
37.3 wks33.4 wksOSPlat Res
28.8 wks28.4 wksTTP Plat Sens
6.5 wks12.3 wksTTP Plat Res
12*16*PR
5*4*CR
ORR
18.3 wks18.4 wksTime to progression
Topotecan (n = 119)
Doxil (n = 118)
Examples of Nanoparticles for Drug Delivery
DOXIL Future improvements?
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• Non-toxic vehicle• Non-immunogenic• Condensation of DNA• Intracellular delivery• Targeting ligand• Stabilization of
particles
IDEAL SYSTEMIC DELIVERY VECTOR
• Ave. MW 5.8 kDa, polydispersity index Mw/Mn = 1.12• Degree of polymerization ~ 5 (10 charges/chain)
verified by end group analysis and light scattering
CYCLODEXTRIN POLYMER
Gonzalez et al. Bioconjugate Chemistry (1999) v10:1068-1074
OHO
OHO
OHO
OHO
O
HO
HO
OO
OHHOO
OOH
OHO
O
OH
OOH
O
HOOOH
OH
OH
S
OH
HO
HO
SHN H
N
NH2+ NH2
+S
X
OHO
OHO
OHO
OHO
O
HO
HO
OO
OHHOO
OOH
OHO
O
OH
OOH
O
OH
OOH
OH
OH
OH
HO
HO
SNH2
(CH2)6
H2N
PARTICLE ASSEMBLYDNA
(a)
(b)
200 nm
OHO
OHO
OHO
OHO
O
HO
HO
OO
OHHOO
OOH
OHO
O
OH
OOH
O
HOOOH
OH
OH
S
OH
HO
HO
SHN H
N
NH2+ NH2
+S
X
OHO
OHO
OHO
OHO
O
HO
HO
OO
OHHOO
OOH
OHO
O
OH
OOH
O
OH
OOH
OH
OH
OH
HO
HO
SNH2
(CH2)6
H2N
TRANSFECTION COMPARISON
Gonzalez et al. Bioconjugate Chemistry (1999) v10:1068-1074
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
Back
grou
nd
Poly
-L-L
ysin
e
Supe
rfect
(Den
drim
er)
Lipo
fect
amin
e
CD
-pol
ymer
4 PEI
Rel
ativ
e Li
ght U
nits
BHK-21CHO-K1
Lipid,LipofectamineIC50=6.4 µM
PolycationSuperfect
IC50=11 µM
CyclodextrinpolymerIC50=320 µM
Polymer PEIIC50=23µM
IC50 values reported as charge concentrations in the presence of DNA
TOXICITY COMPARISON TO BHK-21 CELLS
Association Constant is 104–105
INCLUSION COMPLEX FORMATION
+
11
LLL
LL
L
L
LL
LL
L
L
L
L
L
L
LLLLLLL
LL
L
L
LL
LL
L
L
L
L
L
L
LL
L
L
LL
LL
L
L
L
L
L
L
LL
L
L
LL
LL
L
L
L
L
L
LPre-formed Particle
Stabilized Particle
Targeted, Stabilized Particle
PEG-Ad
Ligand-PEG-Ad
NEW METHOD OF SURFACE MODIFICATION
Pun and Davis Bioconjugate Chemistry (2002 ) v13:630
C D
BA A. Polyplexes in waterB. PEGylated polyplexes
in waterC. Polyplexes in 50 mM
NaClD. PEGylated polyplexes
in 50 mM NaCl
Space bar is 100 nm except in C where itis 1000 nm
TEM IMAGES OF PARTICLES
Pun and Davis Bioconjugate Chemistry (2002 ) v13:630
Targeted Particles
Pun, et al. Canc Biol Ther (in press)
Biodistribution
Nucleic acid delivery Nanoparticle delivery
Pun, et al. Canc Biol Ther (in press)
Tumor uptake
Pun, et al. Canc Biol Ther (in press)
Nucleic acid delivery Nanoparticle delivery