Download 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