Abstract: Long Project
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Transcript Abstract: Long Project
April 27th 2010
Mary Coan
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
Image: http://www.nature.com/nnano/journal/v3/n3/covers/index.html
Introduction
Acute intoxications, either accidental or intentional, constitute a
major public health problem worldwide
Due to the cost burden placed onto the hospital, patient, or the
public depending on the healthcare system provided
Illicit drug use plays a profoundly large role in number of treated
acute intoxication cases
Approximately 40%
Significant number of deaths are due to over the counter drug
overdoses
Analgesics
Antidepressants
Sedatives/hypnotics/antipsychotics
Stimulants
Cardiovascular
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image; http://www.topnews.in/health/files/cholesterol-lowering-drugs.jpg
Introduction
Many acute intoxication cases result in life-threatening
situations
Typical treatment for conscious patients in these cases
consists of
Emptying the stomach
Administering activated charcoal
Gastric emptying
Whole bowel irrigation
Haemodialysis
Correction of electrolyte disturbances
Adminstering I-V fluids
Removal of toxins through extracorporeal procedures
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://eslpod.com/eslpod_blog/wp-content/uploads/2008/02/emergency-1.jpg
Introduction
Some of the listed treatments
can be used on the
unconscious
Whole bowel irrigation and
haemodialysis are generally
reserved for eliminating
specific life-threatening toxins
from the body
Antidotes are rarely available
and/or exist
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://pencilsatdawn.wordpress.com/2007/07/14/antidote/
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
Image: http://best.rutgers.edu/files/imagecache/featured_block_1/testtubes_3.JPG
Current Standard Detoxification Methods:
Administration of an Antidote
There are antidotes for specific cases
Organophosphate/Carbamate insecticide
Atropine
Acetaminophen
N-Acetylcysteine (NAC)/Mucomyst®
Narcotic overdose
Naloxone/Narcan®
There are many more antidotes that are specifically for
chemical exposure or poisonous bites not for drug
overdoses
http://www.rphworld.com/viewlink-25090.html
Image: http://store.vitaminliving.com/images/uploads/IV_Bag.jpg
Current Standard Detoxification Methods:
Administration of an Antidote
All of these antidotes can be given via an IV or shot
Example of a largely used antidote is Narcan®
Non-habit forming and causes no long-term side effects
Sudden reversal of a heroin high can induce vomiting
Supplied to thousands of Heroin addicts by local government
programs to reverse a drug overdose
Thousands have been saved since the induction of the program in a
select few cities
http://www.boston.com/news/local/articles/2007/11/02/addicts_to_receive_overdose_antidote/
Image: http://www.abconlinepharmacy.com/ns/imagem.php?masterid=1299
Current Standard Detoxification Methods:
Gastric Emptying
For patients that swallow any poisonous
substance, not including alcohol, the
following procedure is typically followed:
IV fluids are administered and
continued
Activated charcoal is administered
1.
2.
a)
b)
3.
Orally via a black drink, if the patient is
awake and alert
Orally through a tube, if the patient is not
awake
Adsorbs and eliminates drugs/metabolites
that are still present or being secreted in
the gastrointestinal track
Observe the patient and administer any
anti-vomiting medicine as needed
http://www.emedicinehealth.com/activated_charcoal/article_em.htm
Image: http://www.krider.com/MPj03211260000%5B1%5D.jpg
Current Standard Detoxification Methods:
Gastric Emptying
Whole Bowel Irrigation is also used to remove toxins from
the entire gastrointestinal tract (GI tract)
Flushes the GI tract of everything including any ingested
toxins
Typically used only for toxins that are not absorbed by
activated charcoal
Iron
Lithium
Sustained-release or Enteric-coated Drugs
Both procedures can not remove any of the toxins already
absorbed into the patient’s blood stream
http://emedicine.medscape.com/article/1413446-overview
Current Standard Detoxification Methods:
Gastric Emptying
In the case of Ethanol intoxication Gastric
Lavage is used to remove the contents of
the stomach
Used in patients that are not vomiting
A tube is passed through the mouth to the
stomach followed by sequential
administration and removal of small
volumes of liquid via suction
Can be used in the cases of Drug related
intoxication if used within 1 hour of
consumption
Overdoses can lead to the following if the
patient is not treated quickly:
Permanent brain/nervous system damage
Comas
Death
Image: http://emptyyourcup.com/blog/uploaded/iStock_000003492238Small_9.jpg
http://wps.prenhall.com/wps/media/objects/737/755395/gastric_lavage.pdf
Current Standard Detoxification Methods:
Removal of Toxins
Many cases an antidote does not exist and the patient did not
orally ingest the drug
Only solution is to remove the toxins from the blood stream
Hemodialysis is the only readily available procedure to remove
toxins from the blood stream
Removes substances from the patient’s blood by passing the blood
through a semi-permeable membrane in a bedside dialysis
machine
Suited for drugs or metabolites that are
water soluble
low volume of distribution, generally remains in the blood stream not in
the organs
Molecular weight below 500 g/mol
Low plasma protein binding
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Current Standard Detoxification Methods:
Removal of Toxins
An emerging strategy for removing
toxins from the blood stream
Injected nanosized particulate
carriers (< 1 μm) that act as a sink for
the toxin
When a toxic dose of a chemical
enters a patient’s blood stream,
elevation of the patient’s tissue
concentrations above the minimum
toxic level (MTL), represented by the
blue line, occurs
Toxic levels are maintained until the
toxic chemical diffuses and/or
metabolizes out of the patients tissues
(organs)
Resulting in a decrease of tissue
concentrations (upper curve)
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Current Standard Detoxification Methods:
Removal of Toxins
Nanocarriers absorb the
toxin from the blood
stream and/or the tissue
Allows for the
redistribution of the toxic
chemical from the
peripheral tissues into the
blood compartment
Reduces tissue exposure to
the toxic compound
By bringing the tissues
concentration below the MTL
at a faster rate (lower curve)
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Current Standard Detoxification Methods:
Removal of Toxins
Injected nanocarriers exit the body via the kidneys or the
liver
Natural excretion of the nanocarriers is acceptable and
preferred
Saves money, time and reduces the patients risk of surgery
Once the toxic chemical is sequestered by the nanocarriers it will
not leach back into the body
Nanosized carriers can take on different forms
Liposomes
Nanoemulsions
Nanoparticles
Macromolecules
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image 1: http://media-2.web.britannica.com/eb-media/37/96837-004-AAC9A5BB.jpg ,Image 2: http://www.pharmoscorp.com/development/nanotechnology.html ,Image 3: http://radioweblogs.com/0105910/images/nanoparticles.jpg , Image 4: http://www.rsc.org/ejga/SM/2008/b807696k-ga.gif
Current Standard Detoxification Methods:
Removal of Toxins
Several of the listed nanocarriers can function as
detoxifiers
Detoxifiers Properties
High Specific Surface Area
Adjustbale Composition/Surface Porperties
Manipulated to optimize uptake and circulation time.
Nanocarriers used biodetoxification usually share the
same characteristics as those used in drug delivery
Except the affinity of the toxic agent to the carrier
should be very high to ensure rapid and efficient removal of
toxins from the peripheral tissues.
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
http://www.rsc.org/ejga/CP/2010/b914440d-ga.gif
Nanocarrier Biodetoxification
There are several parameters of the toxic chemical to be
considered in toxicity reversal
Molecular weight
Ionization constant
Affinity for blood proteins (Vd)
Half-life
Toxicological profile
Presence of active metabolites
Potential toxicity of metabolites
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007
doi:10.1038/nnano.2007.339
Image: http://www.3dchem.com/imagesofmolecules/Cocaine.jpg
Nanocarrier Biodetoxification
Most drugs involved in poisoning are weak bases that are
characterized by a large Vd
High protein binding and the presence of active metabolites
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Large Vd‘s can complicate the detoxification procedure
Especially in the case of a slow transfer rate of the toxins from the
tissues to the blood
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
When drugs bind to blood proteins the extraction efficiency is
lowered
Less drug is available for capture
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
In most laboratory settings
The nanocarrier is administered prior to or within minutes
following exposure to the drug
In many cases the intoxicated patient is admitted to a hospital
3-4 hours after the drug has entered the patient’s body
Large amounts of the drug may have been converted into active
metabolites
Some drugs are inactive until contact with a certain bodily fluid, e.g.
Silvia, Stomach Acid, Other GI fluids, when they become activated
For example, upon oral absorption almost instantaneously 40% of
amitriptyline, an antidepressant, is metabolized by the liver into
its active demethylated form
Nortriptyline
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Schematic representation
of the multiple effects of
cannabis smoking on basic
enzymatic and
physiological mechanisms.
These effects are mediated
by r9-THC and possibly by
active metabolites, and
lead to the development of
functional and metabolic
tolerance.
Image:
http://www.unodc.org/images/odccp/bulletin/bull
etin_1973-01-01_1_page003_img003_large.gif
Nanocarrier Biodetoxification
Injectable nanocarriers need to meet a number of
criteria including but not limited to:
Innocuousness
Circulation time
Uptake capacity
In order for the injected carrier to be successful
Must remain in the blood stream and/or tissues
Long enough for the toxic agent to be extracted sufficiently
from the blood stream and peripheral tissues
Short enough so that the toxic agent isn't leached back into
the bloodstream and/or tissues
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
The human body’s response to
nanocarriers is very similar to
colloids
Circulation time of a colloid
depends on its hydrodynamic
volume, shape and surface
properties
Spherical colloids, maximum
circulation times are obtained
for those with diameters
between 50–200 nm
Very small colloids (< 8 nm) are
excreted by the kidneys and/or
rapidly accumulate in the liver,
whereas large particles (> 200
nm) are subjected to major
uptake by the spleen
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image 1: http://focus.aps.org/story/v20/st21
Nanocarrier Biodetoxification
Nanocarriers coated with
hydrophilic, flexible polymers such
as polyethylene glycol (PEG)
Slow down the immune system
clearance time
Improve the half-life in blood
Nanocarriers with extracted toxins
are generally eliminated from the
bloodstream within 24 hr and
mostly end up in the liver where the
toxic compound is metabolized
Most drugs rarely cause any
significant liver damage upon acute
poisoning
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://www.technologyreview.com/read_article.aspx?id=17578&ch=nanotech&a=f
Nanocarrier Biodetoxification
Quickly decreasing tissue concentrations below the toxic
threshold requires the drug to ideally be completely and
rapidly captured
Oil(lipid)-based nanocarriers
Selected lipids need to highly compatible with the toxin
Many hydrophobic and amphiphilic drugs are poorly soluble in
injectable lipids
Large amounts of the nanocarrier dose is required to extract the toxic
agent
Infusing high amounts of lipids may be acceptable in the context
of detoxification and potentially saving a life
Injecting large doses of nanocarriers (> 1 g/kg or > 5 ml/kg for a typical
20%-lipid emulsion) can slow down the detoxification process
Increases the time during which the nanocarrier is administered
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://www.biotargeting.eu/images/%28master%29_0001.png
Nanocarrier Biodetoxification
Typically the partition coefficient, or the solubility of two solvents,
for the oil phase is the main parameter used to eliminate possible
mixtures
For the uptake of toxic agents by oil-based nanostructures this is not the
case
Amphiphilic compounds that possess hydrophilic and hydrophobic properties
can adsorb at the oil/water interface
Adsorption depends on specific surface area
Depends on particle size
Extraction capacity generally increases with decreasing particle size
For the case of amphiphilic charged drugs
Adsorption at the interface between the nanocarrier and the drug can be
enhanced by adding an oppositely charged component to the
nanocarrier’s surface that interacts electro-statically with the drug
Chemically modifying the nanocarrier with specific functional
groups can increase drug uptake and improve extraction
Example, electron-deficient aromatic rings that bind to compounds with
π-electron-rich aromatic rings
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
An alternative strategy to
optimize extraction is to
create an concentration
gradient between the
inside and outside of the
nanocarrier
This can be achieved by
encapsulating an
enzyme that degrades
the toxic agent into
water-filled vesicular
structures
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Toxins diffuse into the carrier
Are metabolized by the
enzymes
Thus more toxic compounds
can be pumped into the
carrier
This system requires
The toxic agent to freely
permeate the vesicle
membranes
The entrapped enzyme to
remain active for at least a
few hours while circulating
in the blood
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Optimization of the extraction of ionizable drugs
Including weak bases or acids
Sequesters the toxic agent into nanosized vesicles by
creating a transmembrane pH gradient
Similar to the urinary pH manipulation technique
Used by clinicians to accelerate excretion of ionizable drugs from
the kidneys
Neutral low-molecular-weight weak acids and bases can
permeate vesicle membranes at much faster rates than
their ionized forms
This extraction process is very efficient, even for
molecules that are highly protein-bound
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
If a vesicle exhibits a pH
gradient (acidic or basic for
weak bases or acids), the
unionized compound
diffuses down its
concentration gradient into
the vesicle interior where it
is subsequently ionized and
trapped
The diffusion of the toxic
agent’s neutral form will
continue until the interior
buffering capacity is
overwhelmed
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Several colloidal carriers have been investigated for
detoxification applications over the past two decades
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification
Sizes ranging from a few nanometres (polymers) to
half a micrometrer (emulsions in parenteral nutrition)
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
Nanocarrier Biodetoxification:
Liposomes
Liposomes
Spherical vesicles
Possess one or more
concentric phospholipid
bilayer membrane(s)
Have been extensively
studied for the treatment
of intoxications due to
organophosphorus agents
(OPs)
Toxic agents commonly
found in agriculture
pesticides
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://media-2.web.britannica.com/eb-media/37/96837-004-AAC9A5BB.jpg
Nanocarrier Biodetoxification:
Liposomes
First use of liposomes as
antidotes for OPs was a
follow-up to the work of
Way and co-workers
Cyanide
and/or OPs
Resealed red blood cells
served as vesicles to
encapsulate the enzymes
rhodanese and
organophosphorus acid
anhydrolase (OPAA)
Rhodanese
and/or (OPAA)
Degrade cyanide and OPs,
respectively
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Leung, P. et al. Encapsulation of thiosulfate:cyanide sulfurtransferase by mouse erythrocytes. Toxicol Appl. Pharmacol. 83, 101–107 (1986). Pei, L., Petrikovics, I. & Way,
J. L. Antagonism of the lethal effects of paraoxon by carrier erythrocytes containing phosphotriesterase. Fundam. Appl. Toxicol. 28, 209–214 (1995).
Nanocarrier Biodetoxification:
Liposomes
The approach was later
refined by entrapping OPAA
in neutral long-circulating
PEGylated liposomes
Liposomes were chosen to
replace the red blood cells in
Way’s work due to the
following factors:
Built from non-human-
Enviromental SEM image of bilayer
construction of several liposomes
Image: http://uber-life.net/technology/liposomes.shtml
derived material
Possible large-scale
production
Exhibit a greater shelf-life
than red blood cells
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339 Petrikovics, I. et al.
Antagonism of paraoxon intoxication by recombinant phosphotriesterase encapsulated within sterically stabilized liposomes. Toxicol. Appl. Pharmacol. 156, 56–63 (1999). Petrikovics, I. et
al. Comparing therapeutic and prophylactic protection against the lethal effect of paraoxon. Toxicol. Sci. 77, 258–262 (2004). Petrikovics, I. et al. Long circulating liposomes encapsulating
organophosphorus acid anhydrolase in diisopropylfluorophosphate antagonism. Toxicol. Sci. 57, 16–21 (2000).
Nanocarrier Biodetoxification:
Liposomes
Replacing the red blood cells with liposomal OPAA in mice
resulted in an efficient detoxifier for Ops
However, liposomal OPAA is only effective when administered in
prevention cases
Prior to intoxication
Application of lipomal OPAA after injection of OP, resulted in
substantial increase of OP-induced mortality
A more probable situation to happen under real conditions of
intoxication
Although these data confirmed the therapeutic value of
liposomal OPAA, they also revealed how important timing is
in reversing intoxications
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Petrikovics, I. et al. Antagonism of paraoxon intoxication by recombinant phosphotriesterase encapsulated within sterically stabilized liposomes. Toxicol. Appl. Pharmacol. 156, 56–63
(1999). Petrikovics, I. et al. Comparing therapeutic and prophylactic protection against the lethal effect of paraoxon. Toxicol. Sci. 77, 258–262 (2004).
Nanocarrier Biodetoxification:
Liposomes
Previously mentioned, transmembrane pH gradients can help
remove low-molecular-weight weak acids or bases from
physiological media
Mayer et al. used stealth (long-circulating) liposomes with an
internal pH of 4 as the detoxifying nanocarrier
Administered prior to the injection of a toxic dose of the anti-cancer
drug doxorubicin
Captured the drug in vivo
Decreased its toxicity
Maintained the drug’s anti-tumor potency
The pH gradient was maintained with a decrease of only “1.5 units
over 20 hrs following injection”
Doxorubicin could be sequestered in situ at clinically relevant doses
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Mayer, L. D., Reamer, J. &
Bally, M. B. Intravenous pretreatment with empty pH gradient liposomes alters the pharmacokinetics and toxicity of doxorubicin through in vivo active drug encapsulation. J. Pharm.
Sci. 88, 96–102 (1999).
Nanocarrier Biodetoxification:
Liposomes
Mayer’s study showed that pre-treatment with empty
liposomes could improve the pharmacokinetic profiles
of drugs
Along with their potential as detoxifying agents
pH gradient spherulites were investigated by Dr. Babu
Dhanikula to counteract an overdose of amitriptyline
A type of multilamellar liposome made from uniformly
spaced concentric bilayers
Amitriptyline is a potentially cardiotoxic antidepressant
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Babu Dhanikula, A.,
Lamontagne, D. & Leroux, J. C. Rescue of amitriptyline-intoxicated hearts with nanosized vesicles. Cardiovasc. Res. 74, 480–486 (2007). Simard, P., Hoarau, D., Khalid, M. N., Roux, E. &
Leroux, J. C. Preparation and in vivo evaluation of PEGylated spherulite formulations. Biochim. Biophys. Acta 1715, 37–48 (2005).
Nanocarrier Biodetoxification:
Isolated hearts were first
Liposomes
coated with amitriptyline
at a large enough
concentration to cause
cardio-toxicity
Immediate infusion of pHgradient spherulites
resulted the recovery of the
heart rate
Spherulite concentration
in this investigation could
be readily achieved in vivo
Heart-rate recovery after intoxication and addition of a nanocarrier. Overdose of
amitriptyline elevates heart rates and brings about deleterious effects on the heart
(cardiotoxicity). Isolated rat hearts were infused for 12 min with amitriptyline to
cause intoxication and subsequently perfused with pH 7.4 buffer (red squares),
pH 7.4 spherulites (black triangles), or pH 3.0 gradient spherulites (green circles)
from 15 to 37 min. Perfusion of pH 3.0 gradient spherulites resulted in swift
recovery of heart rate to its initial value because the nanocarrier extracted
amitriptyline from the heart tissue and the protonated drug was sequestered
within the vesicle aqueous core. The black arrows indicate the time during which
the difference in heart beats between the pH 3.0 spherulite and pH 7.4 buffer
group was statistically significant (p<0.01).
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Babu Dhanikula, A.,
Lamontagne, D. & Leroux, J. C. Rescue of amitriptyline-intoxicated hearts with nanosized vesicles. Cardiovasc. Res. 74, 480–486 (2007).
Nanocarrier Biodetoxification:
Liposomes
Diethylene tri-amine penta-acetic acid (DTPA) is typically
used to decontaminate individuals who have been exposed
to toxic heavy metals such as ytterbium and plutonium
DTPA is a molecule that binds cations
DTPA-Pu/Yb complexes are stable and soluble
Easily eliminated from the body via urine
Incorporated DTPA in liposomes resulted in
An increase in DTPA’s half-life
Promotes DTPA’s deposition into tissues
Such as the liver and bone where heavy metals tend to accumulate
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Liposomes
Fattal prepared uncoated and PEGylated liposomes containing DTPA
ranging from 100 to 1600 nm
Assessed their Pu decorporation capacities
Encapsulated DTPA resulted in
A 3- to 90-fold decrease in circulation time when compared to small stealth
liposomes
Substantial DTPA deposition in the liver regardless of the liposome
formulation
Comparatively higher levels of DTPA in the bone compared to the free DTPA
Liposomal DTPA improved the Pu excretion
Reducing the total Pu burden 30 days after toxic exposure
Liposomes have proven to be effective antidotes for amphiphilic compounds
that can be inactivated by encapsulated enzymes or actively trapped within
their aqueous compartments
But they may not be ideal for highly hydrophobic and poorly or non-ionizable
molecules
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Phan, G. et al.
Pharmacokinetics of DTPA entrapped in conventional and long-circulating liposomes of different size for plutonium decorporation. J. Controlled Release 110, 177–188 (2005), Phan, G. et al.
Enhanced decorporation of plutonium by DTPA encapsulated in small PEG-coated liposomes. Biochimie 88, 1843–1849 (2006).
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
NanoEmulsion:
Conclusion
http://www.aapspharmscitech.org/articles/pt0804
/pt0804104/pt0804104_figure2.jpg
Nanocarrier Biodetoxification:
Nanoemulsions For highly hydrophobic and
poorly or non-ionizable
molecules
Colloidal systems such as
nanoemulsions, where drug
uptake mostly relies on a
favorable partition coefficient
for oil droplets, may be more
appropriate than liposomes
Nanoemulsions are nanosized
droplets of oil dispersed in an
aqueous phase
Ionizable drugs may exhibit a
Image: http://artsci.ucla.edu/biotech177/blog/?p=821
high affinity for oils or
oil/water interfaces
Can be extracted by
nanoemulsions
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Nanoemulsions
Intralipid is a soybean oil-in-water emulsion (~ 430 nm diameter)
that is stabilized with egg phosphatidylcholine lipid
Commonly injected as a source of triglycerides for individuals who
cannot ingest fats orally
Evaluated as a detoxifier for hydrophobic drugs such as bupivacaine
Local anaesthetic associated with occasional but severe and potentially
lethal cardiotoxicity
Infusion of Intralipid immediately after the injection of a lethal dose
of bupivacaine increased survival rates significantly in animals
The mechanism is not fully understood due to the low affinity of
bupivacaine for Intralipid
The positive effect of the treatment could be partially attributed to the
large dose of lipids injected (several grams of triglycerides per
kilogram), which favors drug partition to the oil phase
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Nanoemulsions
Effect of pre- and post-dosing of PEGylated tricaprylin
emulsions on the pharmacokinetics and biodistribution of
docetaxel were studied
PEGylated tricaprylin emulsions are triglyceride based emulsions
Docetaxel is a non-ionisable anticancer drug
Injection of the PEGylated tricaprylin emulsion 20 minutes
after docetaxel was administered resulted in a rapid decrease
in the drug concentration in the blood pool
After uptake by the emulsion, the drug was mainly redirected to
the liver and spleen
These studies illustrate that nanoemulsions can and have
extracted drugs that have already been distributed to
peripheral tissues
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Nanoemulsions
Emulsions are particularly attractive in the biomedical field
Can be prepared from generally recognized safe experiments
Often face inherent formulation issues arising from
thermodynamic instability
Leads to the coalescence of oil droplets over time or their
disassembly in the bloodstream
Emulsion long-term stability is limited by difficulties in
obtaining dry formulations for prolonged storage
Particularly relevant in the context of detoxification
Turnover is expected to be low
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Nanoemulsions
To enhance stability,
nanoemulsions can be
coated with a hard
polymeric shell
Formation of nanocapsules
Resulting in a nanocarrier
that is more robust and
controls drug uptake
kinetics
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Image: http://www.uni-bielefeld.de/chemie/ac1/images/HAOFig.6.jpg
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
Nanoparticle Image:
http://library.thinkquest.org/07aug/02147/images/
nanoparticle.jpg
Nanocarrier Biodetoxification:
Nanoparticles
Underhill et al. used hexadecane-filled polysiloxane -
silicate nanocapsules to sequester bupivacaine and
quinoline in vitro
Resulted in the rapid removal of bupivacaine and quinoline
from a normal saline solution
Even with good results, the low biodegradability of their
polymeric shell and the nanocapsules interaction with
blood components, i.e. rupturing red blood cells and
delaying clotting time, would hamper their use in clinical
studies
PEGylation of these nanocapsules resulted an improved
blood compatibility
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Underhill,
R. S. et al. Oil-filled silica nanocapsules for lipophilic drug uptake: implications for drug detoxification therapy. Chem. Mater. 14, 4919–4925 (2002).
Nanocarrier Biodetoxification:
Nanoparticles
Injectable magnetic
Iron nanoparticles made in Professor Diandra LesliePelecky’s lab are spherical and uniformly sized, a
highly desired goal in producing nanoparticles.
http://www.utdallas.edu/news/2008/10/11-003.php
nanospheres was recently
stuided to remove
deleterious compounds
Magnetic nanospheres were
functionalized with ligands
that recognize a particular
toxin
Once bound to the ligand
on the carrier, the toxin is
removed using a magnetic
filter unit
This system is still in the
early development stages
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromolecule Carriers
Future Work
Conclusion
Bom, A. et al. A novel concept of reversing neuromuscular blok:
chemical encapsulation of rocuronium bromide by a cyclodextrinbased synthetic host. Angew. Chem. Int. Edn 41, 266–270 (2002).
Nanocarrier Biodetoxification:
Macromolecule Carriers
Water-soluble macromolecules have been investigated as
nanomedicines for more than three decades
Increase the circulation time of bound drugs
Improve their site-specific delivery
Whole antibodies and antibody fragments represent one of the
most studied classes of macromolecular carriers
Whole antibodies and antibody fragments macromolecular
carrier’s first documented therapeutic human application dates
back to the 1970’s
Treatment of digitalis (a cardiovascular drug) intoxication
Since the concept has been applied with some success to several
drugs and toxins
Amitriptyline
Colchicine
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Macromolecule Carriers
Using antibody macromolecule
carriers for detoxification is
potentially very powerful
Antibody Fragments
Due to the high specificity and
affinity of the antibody–antigen
interaction
However, in order to produce specific
high affinity antibodies directed
towards the toxic compound, the
antibodies should have an immunogenic character
which is not generally the case
Another draw back is that each antibody or antibody fragment can
neutralize a limited number of toxic molecules
Thus, this approach is appropriate for compounds that are toxic at very low
doses
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339, Image:
http://www.macrocrystal.com/gfx/crystal_company.jpg
Nanocarrier Biodetoxification:
Macromolecule Carriers
A non-immune macromolecule such as cyclodextrin can
also reverse the pharmacological effect of drugs
An example of a non-immune macromolecule is
Sugammadex
A novel γ-cyclodextrin based molecule that forms an
exceptionally stable 1:1 complex with the neuromuscular
blocking agent, rocuronium
Neuromuscular blocking drugs are used to relax muscles
during surgery
After completion of the surgery, these drugs are often
neutralized with a pharmacological agent to accelerate
recovery from neuromuscular blockade
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Macromolecule Carriers
In the drug Sugammadex
Dextrose units of cyclodextrin were
modified
Better accommodate the rocuronium
Enhance the electrostatic interactions
between cyclodextrin and rocuronium
The intravenous injection of
Sugammadex was shown to deplete the
free rocuronium in plasma and enhance
its urinary excretion
Several clinical studies have clearly
established the remarkable efficacy of
Sugammadex at quickly reversing the
neuromuscular block without inducing
serious adverse events
Sugammadex simulation
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339 Naguib, M. Sugammadex: another milestone in
clinical neuromuscular pharmacology. Anesth. Analg. 104, 575–581 (2007). Image: http://upload.wikimedia.org/wikipedia/commons/4/42/Sugammadex_sodium_3D_front_view.png
Nanocarrier Biodetoxification:
Macromolecule Carriers
Another non-immune based macromolecule carrier that
has been studied is oligochitosan
Linear biodegradable copolymer of N-acetyl-D-glucosamine
and D-glucosamine
Studied as a detoxifier for amitriptyline
Oligochitosan was modified with dinitrobenzenesulfonyl
groups to selectively bind amitriptyline via π–π interactions
The modified polymer seemed inert
Did not affect blood clotting in vitro
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nanocarrier Biodetoxification:
Macromolecule Carriers
Coating isolated hearts with the modified-polymer
complex reduced amitriptyline’s cardiotoxicity
The unmodified polymer had no effect on the cardiotoxicity
This study proves that the amitriptyline binding to the
chitosan derivative prevents the drug from diffusing into
the heart tissue
There is a potential for liver toxicity due to the
dinitrobenzylsulfonide moiety
Could arise at the high doses that are required for
biodetoxification
Needs further investigation
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
http://xianrenaud.typepad.com/photos/uncategor
Conclusion
ized/2008/02/29/futurework.jpg
Future Work
Nanocarriers may also be used to sequester high-
molecular-weight hydrophilic toxins
Reverse polymeric micelles from hyperbranched and starshape polymers can be tailored to take up macromolecules
in their hydrophilic inner core
Critical features of polymeric micelles as drug carriers can be
modulated by engineering the constituent block copolymers
Unlike PEG-liposomes, polymeric micelles might show a
tumor-infiltrating ability
Development of polymeric micelles with smart functions
Environment-sensitivity
Specific tissue-target ability
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339
Nishiyama, N. and Kattaoka, K. “Current state, achievements and future prosepects of polymetric micelles as nanocarriers for drug and gene delevery” Pharm. And
Therapeutics, VOL 112 Issue 3 December 2006 doi:10.1016/j.pharmthera.2006.05.006
Future Work
http://www.nanocarrier.co.jp/en/ir/business.html
Outline
Introduction
Current Standard Detoxification Methods
Administration of an Antidote
Gastric Emptying
Removal of Toxins
Nanocarrier Biodetoxification
Liposomes
Nanoemulsions
Nanoparticles
Macromoleculues Carriers
Future Work
Conclusion
http://www.irvinehousingblog.com/wpcontent/uploads/2007/04/sheeple.gif
Conclusion
Since liposomes were first proposed as a means of treating poisoning
almost 35 years ago, tremendous progress has been made in perfecting
nanocarriers for biodetoxification applications
Only a single system developed so far has reached the clinical stage
This is due to combining properties such as biocompatibility, long
circulation time, stability and high extraction efficacy
Recent advances in the field of nanotechnology may be exploited to
successfully attain this goal
Instability problems commonly encountered with liposomes can be
circumvented by engineering nanosized vesicles from biodegradable
multiblock polymers or shell crosslinked nanocages
The affinity between the drug and nanocarrier can be enhanced by
using molecular imprinting techniques
Polymeric matrices are imprinted with a template (which could, for
example, be made from a drug) and are then washed away
This leaves vacant sites that can rebind the imprinted molecule with
high specificity and affinity
Dr. Jean-Christophe Leroux, "Injectable nanocarriers for biodetoxification" nature nanotechnology | VOL 2 | NOVEMBER 2007 doi:10.1038/nnano.2007.339