Date post: | 18-Jul-2015 |
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Health & Medicine |
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Dr Manjuprasad
Moderator:Dr Princy Palatty
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OVERVIEW
Introduction
Need for novel drug delivery system
Types
Advantages
Disadvantages
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INTRODUCTION:
• Method of drug delivery can have a significant effect on its efficacy.
• Some drugs have an optimum concentration range within which maximum benefit is derived, and concentrations above or below this range can be toxic or produce no therapeutic benefit at all.
• From this, new ideas on controlling the pharmacokinetic ,pharmacodynamics , non-specific toxicity, immunogenicity, biorecognition , and efficacy of drugs were generated.
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Ideal characteristics:
• Convenient to administer
• Economical
• Should not require special skills
• Should not cause pain
• Continuous absorption of drug
• Minimal frequency of administration
• Should not be embarassing
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CONVENTIONAL DRUG DELIVERY
• Enteral
• Parenteral- injections
-inhalation
-transdermal
-transmucosal
• Local
NEED FOR NOVEL DRUG DELIVERY
To maximize therapeutic effect
To minimize adverse effects
To increase bioavailability
To minimize drug degradation
To improve compliance
To reduce the overall health cost
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CLASSIFICATION
Drug vehicles
Drug devices
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DRUG VEHICLES
MICROSPONGES:
Biologically porous inert particles, made up of
synthetic polymers with the capacity to store a
volume of an active agent upto their own weight
eg: Retin A for acne vulgaris
Carac containing flurouracil
for actinic keratosis
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IMMUNOCONJUGATES
• Monoclonal antibodies are conjugated with
drug/radioisotopes
ex: Ibritumomab tiuxetan -
they carry Cancer killing radioactive particles
directly to cancer cells of
non-hodgkins lymphoma
• Attacks cancer cells
minimizing harm to healthy tissues
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BACTERIOPHAGE
• The phages are loaded with a large payload of a
cytotoxic drug by chemical conjugation.
• the drug hygromycin conjugated to the phages by
a covalent amide bond, or the drug doxorubicin
conjugated to genetically-engineered cathepsin-B
sites on the phage coat.
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VESICULAR SYSTEM
• LIPOSOMES
Liposomes are small vesicles, formed of a bilayer of phospholipid, encapsulating an aqueous space of about 0.03 to 10 microns
The most common vehicle currently used
Non toxic, non hemolytic, non immunogenic even on repeated injection
Produced by sonication of an aqueous suspension of phospholipids
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VIROSOMES
o A virosome is a drug or vaccine delivery
mechanism consisting of unilamellar phospholipid
membrane vesicle incorporating virus derived
proteins to allow the virosomes to fuse with target
cells. Virosomes are not able to replicate.
o This strategy has been proposed for immunization
o Can be administered via mucosa, intradermal,
IM routes
o Eg: HIV1
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CHOCLEATES
o Stable particles derived from liposomes
o Composed mainly of charged phosphatidyl serine
o Chocleate delivery have shown potentiate use of
Amphotericin B
Factor V111
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• COBOSOMES
o Similar to chocleates
o But have a multilayered structure of continuous
lipid bilayer and have self assembly like cube
o They are biocompatible and show bioadhesive
property ideal for oral administration
eg: oral administration of cubosomes loaded with
insulin ( exp was done in rats)
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ETHOSOMES AND TRANSFEROSOMES
o They are like liposomes with increased flexibility
due to addition of ethanol or surfactant
o They are specifically designed for skin delivery
o Ethosomes eg: Minoxidil, acyclovir
o Transferosome eg: oestradiol, norgestrel,insulin
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eLIPOSOMES
o defined as a liposome with internal emulsion
droplets.
o The enclosed emulsion droplets in an eLiposome
add the ability to further control the location and
time of release from the liposome with ultrasound.
o Eg: Doxorubicin
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CYCLODEXTRINS
o family of compounds made up of sugar molecules
bound together in a ring
o 3 types: alpha, beta and gamma
o Beta cyclodextrin is ideal due to large cavity size
o They can act as permeation enhancer to improve
the drug absorption
o Eg: dexamethasone, nitroglycerin, nimesulide ,
iodine
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DENDRIMERS
o Highly branched synthetic
Macromolecules
Biocompatible and biodegradable
o Serve as a hub onto which
a large number of drugs can be
delivered
o Eg:5-FU
methotrexate
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Resealed Erythrocytes
Advantages
Easy isolation
Non immunogenic
Large volume of drug can be given
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Protection from premature degradation
Minimum toxic side effects
Biodegradable
Applications
Oxygen deficiency therapy
Delivery of antiviral agents
Delivery of anticancer drugs
OSMOTIC PUMPS
• small tablet shaped units consisting of drug and
osmotic substance in two different chambers
• Coated with semipermiable membrane which has
minute laser drilled holes for drug release
• Eg: iron
prazosin
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DRUG DEVICES
• Drug eluting stents
o Normal metal stents coated with a pharmacological
agent
o Agents are Sirolimus , Paclitaxel
o Sirolimus is an antiproliferative agent
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o Used in Percutaneous coronary Interventions
o Reduces chances of restenosis from 25% to 50%
• HORMONAL IUCDs
o These are 3rd generation IUCDs
o They release hormone slowly into the uterine
endometrium
o Used as contraceptives , DUB
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o Progestasert
coated with natural progesterone
Releases progesterone @65 micrograms/day
o Mirena
Coated with levonorgestrel
Releases the drug @20micrograms/day
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LASER ASSISTED TRANSDERMAL DRUG
DELIVERY
It creates aqueous micropores not deeper than the
epidermis with the help of laser scanner
Active transdermal delivery is the only way
forward to apply large molecule drugs through skin
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• Norplant
• Norplant is a form of birth control
• developed by Sheldon J. Segal
and Horatio B.
• The original Norplant consisted of a set of six
small (2.4 mm × 34 mm) silicone capsules, each
filled with 36 mg of levonorgestrel
• implanted subdermally in the upper arm and
effective for five years28
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Norplant II , consists of two small (2.5 mm
× 43 mm) silicone rods each containing
75 mg of levonorgestrel, being effective for
five years
• OCUSERT
Pilocarpine is available in an ocusert form
Used in the treatment of glaucoma
Pilocarpine is sandwiched between 2 layers of
ethylene-vinyl acetate membrane
Contains alginic acid which serves as carrier for
pilocarpine
Impregnated with titanium dioxide – makes it
easier for patient to see
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• It is placed in the cul de sac where it floats with
tears
• Tears penetrates the
microporous membrane &
releases pilocarpine
• Pilocarpine can also be
given through contact lenses
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INTRANASAL DRUG DELIVERY TO BRAIN
Drug substances can be transferred along the
olfactory nerve, bypassing BBB & entering the
brain directly
Olfactory transport is along olfactory nerve cells or
along perineural space into the CSF
Immediate drug delivery, sometimes faster than IV
route
Eg: NGF, erythropoetin and IGF
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MICROCHIPS
o They hold drug in a reservoir
o Implanted into the body under LA
o Released with the help of hand held wireless
device
o Important in chronic conditions that require careful
monitoring & precise therapy
o Compliance is improved
o Eg: PTH for osteoporosis
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PATIENT CONTROLLED ANALGESIC SYSTEM
o PCAS refers to electronically controlled, infusion
pumps
o Delivers an amount of intravenous analgesics
o Handled by the patient himself
o Narcotics are the most common analgesics
administered
o Used in cancer treatment & post operative pain
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Fentanyl given in a
lollipop formulation
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DRUG ELUTING MICRO STENTS
Microstents were coated with a polymer-drug
compound and is implanted in the angle of iris and
cornea
Diffusion controlled
release of paclitaxel or
mitomycin is used to
avoid blocking of stent
• IONTOPHORESIS
The use of an electric current to introduce the ions
of a medicament into bodily tissues
An adhesive patch containing thin electrode and
drug containing gel in contact with the skin
Depending upon the dose and energy the drug
either can act locally or
can be carried into blood
stream
Eg: pilocarpine
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USG guided transdermal drug delivery
Eg: Proteins (tPA,)
Insulin
Vaccines
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INSULIN DELIVERY
• INSULIN PENS
Lesser Injection pain
Convenient & easy to handle
More accurate dosing
Easier to use with visual & fine motor
impairments
Disadvantages
Expensive and 2 different insulin cannot be mixed
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IMPLANTABLE INSULIN PUMPS
1.Open loop
2.Closed loop:
• Also called as artificial pancreas
• Main purpose of its development was for the
management of Type1 DM
• Works on the principle of continuous glucose
monitoring of blood, changes on which feedback
will be sent to insulin pump and thus control of
blood sugar
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INSULIN INHALERS
o Inhalable insulin was available from September
2006 to October 2007 in the United States as a new
method of delivering insulin,
o but was found that injectable forms are more
efficient in controlling blood sugars than inhalable
form so was discontinued
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o On 9/13/2011 it was announced that a form of
inhalable insulin, aerosolized insulin, applied
deep into the nostrils may delay the onset
of Alzheimer's disease
o found to have betterment in memory and
mood
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ORAL INSULIN:
A chemical make-up that protects insulin during
passage through the gastrointestinal tract.
Absorption enhancers so that insulin could be
absorbed by the intestine
Rapidly acting insulin is used
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• VACCINE:
o Scientists have developed worlds first drug that
decreases destruction of islet cells
o Drug is a peptide prepared by modifying a
fragment of protein
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• RECTAL DELIVERY:
o bypass of the hepatic first pass metabolism
o The delivery is safe from presence of diet and
encounters less degrading enzymes.
• INSULIN PATCHES: designed to release
insulin slowly and continuously.
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RECENT TRENDS
OF
NANOTECHNOLOGY
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MECHANICAL DRILLING of a small tumor mass by
Nano Robots
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A MICROSCOPIC MACHINE roaming through the blood
stream and taking samples for identification and
determining concentration of different compounds
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MEDICAL NANO DEVICES could augment the
immune system by finding and disabling unwanted
bacteria and viruses
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A NANO ROBOT nibbling on a atheromatous
plaque in a blood vessel
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Clot Inducing Medical Robots are shown in
various stages of clot netting deployment
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Search for the ideal drug delivery system is
on……
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REFERENCES
Goodman & Gillman 12th edition
Target and controlled drug delivery system –novel
carrier system Y S Vyas
Controlled and novel drug delivery system -Sanjay
Jain
Verma RK., Mishra B., Garg S. Osmotically
Controlled Oral Drug
Santini, J. T., Cima M.J. & Langer, R. “A controlled
release microchip.”
Articles from wikipedia , pubmed
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THANK YOU