Protein and peptide drugs offer promising treatment for many diseases. However, their delivery poses challenges due to instability and poor absorption. This document discusses various delivery strategies to overcome these barriers including polymer-based systems, liposomes, and parenteral routes. It also covers formulation approaches like PEGylation and microencapsulation to improve protein stability and pharmacokinetics. Overall, the development of effective protein and peptide delivery systems could enable new therapies for conditions like cancer, diabetes, and more.

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2. PROTEIN AND PEPTIDE
DRUG DELIVERY SYSTEM
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4. Introduction
o In the last three decades therapeutic peptides and proteins have risen in
prominence as potential drug of future.
o The recent advance in large scale fermentation and purification processes and
analytical characterization has widened the horizons.
o Aliments that might be treated with this type of therapeutics include anti-immune
diseases, cancer, mental disorder, hypertension and certain cardiovascular and
metabolic disorders.
o Protein drug must be highly purified and concentrated and have extremely short
half life and should have a shelf life at least two years.
o Recombinant technology has allowed the production of many potential protein
drugs at an acceptable cost, allowing the treatment of severe, chronic and life
threatening diseases.
o Currently over 160 protein drugs are available on the world market, several
hundred s more are in clinical trials
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5. Protein & Peptides
 PROTEINS: Proteins are the large organic compounds made
of amino acids arranged in a linear chain and joined together by
peptide bonds.
Protein > 50 amino acids
 PEPTIDES: These are short polymers formed from the linking,
in a defined order of amino acids.
peptide < 50 amino acids
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 Why protein and peptide are used;
o The protein and peptides are very important in biological cells.
o Lack of proteins and peptides causes diseases like Diabetes
mellitus.
o Diabetes mellitus is caused due to the lack of protein called
INSULIN.
o Now a days R-DNA technology and hybridoma techniques also
used in protein and peptide based pharmaceuticals.
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ADVANTAGES
o Erythropoietin used for production of RBC.
o Tissue plasminogen activator is used for Heart attack, Stroke.
o Oxytocin maintain labor pain.
o Bradykinin increases the peripheral circulation.
o Somatostatin decrease bleeding in gastric ulcer.
o Gonadotropin induce ovulation.
o Insulin maintain blood sugar level.
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FUNCTIONS
o Transport and storage of small molecules.
o Coordinated motion via muscle contraction.
o Mechanical support from fibrous protein.
o Generation and transmission of nerve impulses.
o Enzymatic catalysis.
o Immune protection through antibodies.
o Control of growth and differentiation via hormones
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9. Structure of protein
The structure of protein divided in to four types:
o Primary structure : The amino acid sequence.
o Secondary structure: Regularly repeating local structures
stabilized by hydrogen bond.
o Tertiary structure : Three dimensional structure of
polypeptide.
o Quaternary structure: The structure formed by several protein
molecules (polypeptide chains).
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11. Physico chemical properties of peptides and proteins
o Aqueous solubility of peptide is strongly dependent upon Ph, presence of
metallic ion, ionic strength and temperature.
o At iso electric point the aqueous solubility of peptide is minimal where
the drug is neutral or has no net charge.
o Peptides are very hydrophillic with very low octanol - water partition
coefficient, so as to improve the absorption of peptides by passive
diffusion, their lipophilicity should be increased.
o Molecular size
o Conformational stability
o Sensitivity to light, temperature and biological activity
o Biological half life
o Immunogenicity
o Dose requirements
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12. Instability of proteins and peptides
Physical Instability:
o Denaturation: Non‐proteolytic modification of a unique structure of a
native protein that affects definitechange in physical, chemical and
biological properties. Several examples of denaturating agents are
urea, alcohol, acetic acid, sodium dodecyl sulphate, polyethylene
glycol.
o Adsorption: Ampiphilic nature of protein cause adsorption at various
interfaces like air‐water and air-solid.
o Aggregation and Precipitation: The denatured, unfolded protein may
rearrange in such a manner that hydrophobic amino acid residue of
various molecules associate together to form the aggregates. If
aggregation is on macroscopic scale, precipitation occurs.
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13. Instability of proteins and peptides
Chemical Instability:
o Deamidation: The hydrolysis of the side chain amide linkage of an amino acid
residue leading to the formation of a free carboxylic acid.
o Oxidation and Reduction: Oxidation occurs during isolation, synthesis and
storage of proteins. Temperature, pH, trace amount of metal ion and buffers
influence these reactions. Glucagon is an exception as it retains biological activity
even after oxidation.
o Proteolysis: It may occur on exposing the proteins to harsh conditions like
prolonged exposure to extreme of pH or high temperature or proteolytic enzyme.
o Disulfide exchange: A peptide chain with more than one disulphide can enter in to
this reaction and thereby change in conformation.
o Racemisation: It is alteration of L‐amino acids to D,L‐mixtures. Racemization
form peptide bonds that are sensitive to proteolytic enzymes.
o B‐ elimination: It proceed through a carbanion intermediate. Protein residues
susceptible to it under alkaline conditions include Cys, Lys, Phe, Sre and Thr.
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14. Barriers to protein drug delivery:
o Enzymatic barrier Limits absorption of protein drugs from G.I. tract.
o Intestinal epithelial barrier Involved in the transport of protein drugs
across the intestinal epithelium.
o Capillary endothelial barrier Involved in transport of protein drugs across
the capillary endothelium.
o Blood brain barrier Involved in transport of protein drugs to brain
compartment.
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15. Classification of protein
o Depending on the number of amino acids they are classified as
follows:
 Polypeptides protein
 Oligo-peptides protein
 Fibrous proteins
 Globular proteins
 Oligo-meric proteins
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16. Delivery of proteins
DRUG DELIVERY CLASSIFICATION
Pulmonary Parenteral Transdermal
Implants Ocular Nasal
Miscellaneous Oral
Route of Administration
PEGylation Pro-drug Polymer depot
Drug Modification
Drug Delivery
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Parenteral routes of administration:
o Parenteral route is most efficient way for systemic delivery of
proteins and peptides.
o This is the best choice to achieve therapeutic activity
o Mainly 3 routes of administration
 Intravascular
 Intramuscular
 Subcutaneous
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Advantages
o Route of delivery for 95% of proteins
o Allows rapid and complete absorption
o Avoids first pass metabolism
Disadvantages
o Problems with overdosing, necrosis
o Local tissue reactions/hypersensitivity
o Everyone hates getting a needle
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INTRAVENEOUS ROUTE:
Excessively metabolized and tissue drug bound at the site of IM
can be administered by this route such as Insulin , Interferon
etc.
ADVANTAGES:
Antibiotics can be administered.
DISADVANTAGES:
Causes pain, tissue necrosis and thrombocytopenia.
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 INTRAMUSCULAR ROUTE:
Gamma globulins given by this route are proved to have long-term
protection from hepatic infection. some drugs given by this
route include long acting insulin, GH.
DISADVANTAGES:
Not used for all proteins and peptide drugs because of metabolism
of drugs at the site of injection.
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 SUBCUTANEOUS ROUTE:
o Controlled release is obtained from implantable polymeric
devices.
o These are prepared from crossed linked polymers which are
biocompatible and biodegradable e.g. Poly lactic acid.
o Release of Insulin, bovine serum albumin, LH was prolonged by
this route.
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23. Parenteral drug delivery system
o Polymer based drug delivery system.
o Liposome based drug delivery system.
o Hydro gel based drug delivery system.
o Emulsion based drug delivery system.
PUMPS:
o Implantable infusion pumps
o Mechanical pumps
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24. Polymer based drug delivery system
polymers are used as carriers in this drug
o Pug delivery system.
CHARACTERS OF POLYMERS
o It should be biodegradable.
o It should be bio compatible.
o And non-toxic.
Two types of polymers are used widely
o natural polymers
o synthetic polymers
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25. o Natural polymers: Collagen , hemoglobin and gelatin.
o Synthetic polymers: mainly poly esters like PLA and PGA are
used widely.
o Diffusion of drug out of the polymer
o Drug Release by Polymer Degradation
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o o o
o o o
o o o
o
o o o
o o

26. Liposome based drug delivery
o Spherical vesicles with a phospholipid bilayer
o Liposome's are microscopic vesicles composed of one or more
aqueous compartments.
Liposome’s in Proteins delivery :
Example: Lecithin used in controlled drug release.
Liposome’s in peptide drug delivery:
o Bleomycin : A peptide with anti tumor activity, reduces normal
tissue toxicity.
o Negatively charged liposome's produces a prolonged
hypoglycemic effect in diabetic drugs, which are injected by
subcutaneous injection.
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27. ADVANTAGES OF LIPOSOME DRUG DELIVERY
o Soluble in both organic and aqueous media.
o Liposome’s are important for targeting drugs directly to the
liver, and brain. Lipsosomes easily crosses blood brain barrier.
EXAMPLE: Dopamine converted to L-Dopa.
o Used as a vehicles for vaccines.
DISADVANTAGES
o Less stable , easily susceptible to oxidation.
o Hence liposome’s are replaced by noisome an alternate for
liposome’s.
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28. Hydrogel based dds
Hydrogels are three dimensional networks of hydrophilic
polymers that are insoluble-
o Hydro gels are polymers which have the ability to swell in
water .
o Biodegradable hydro gels are used, due to its biocompatibility .
Examples: Hydroxymethylacrylate, used to minimize mechanical
irritation to surrounding tissue.
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29. EMULSION BASED DELIVERY
o Emulsions can be used for parenteral drug delivery of proteins
and peptides used to prolong the release of drug.
o e.g. subcutaneous administration of muramyl dipeptide in a
w/o emulsion. It is used to potentiate immune system.
CELLULAR CARRIERS
o Protein and peptides can be incorporated in erythrocytes to
achieve the prolong release or targeting.
o Resealed erythrocytes as delivery system for c-reactive protein,
and mainly used to target liver and spleen.
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30. PUMPS
Types of pumps:
IMPLANTABLE PUMPS
o Drug is implanted subcutaneously, and delivered by I.V
infusion.
o Pumps are filled with drug through a septum with a needle.
o Pumps deliver drugs to central vein for 7-14 days a constant rate.
MECHANICAL PUMPS
o Easily manipulated to deliver protein and peptide drugs.
Example: insulin has been successfully delivered by portable
syringe.
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31. NON PARENTERAL ROUTES OF ADMINISTRATION
Parenteral route is not properly achievable, hence other routes are
preferred.
o Oral route.
o Rectal route.
o Nasal route.
o Pulmonary route.
o Buccal route.
o Transdermal route.
o Ocular route
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32. ORAL ROUTE
Encapsulated peptides or proteins in amino acids with
microsphere of approximately 10 micron in diameter , used for
oral delivery.
Example: Insulin and heparin.
Orally administered insulin produces hypoglycemic effect .
DISADVANTAGES:
Acid catalyzed degradation in stomach.
Proteolysis in GIT.
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33. Transdermal route of administration
o This is topical medication.
o Drug is absorbed through the skin.
Ex: Insulin, vasopressin
ADVANTAGES:
o Controlled administration of drug is possible.
o Improved patient compliance.
o Drugs with short half lives can be administered.
DISADVANTAGES:
o High intra and inter patient variability.
o Low permeation because of high molecular weight.
o Hydrophilicity and lipophilicity of stratum corneum.
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34. Number of approaches are available for effective protein and peptide drug
delivery.
 They are
 IONTOPHORESIS
 PHONOPHORESIS
 PENETRATION ENHANCERS
 PRODRUG
 Iontophoresis: Used for local and systemic delivery of proteins and
peptides. In this an electric current is used to drive the molecules across
the skin surface.
Example: Transport of insulin using iontophoresis.
 Phonophoresis: The absorption is enhanced by thermal effect of
ultrasonic waves and subsequent alteration of physical structure of skin
surface.
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35. Pulmonary route of administration
 Lungs are attractive site for systemic delivery of proteins and
peptides because of their enormous surface area(70 sq.m)
 Alveoli and lungs are the absorption sites.
 Drugs are absorbed through lungs by simple diffusion, carrier
mediated transport
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36. ADVANTAGES:
 Decrease in dose requirement.
 Fast absorption
 Increased patient compliance
DISADVANTAGES:
 Inflammation may be observed in lungs.
 Degree of bioavailability was less due to hydrolytic enzymes
present in lungs
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37. Rectal route of administration
 Rectum is highly vascularised body cavity.
 Rectal mucosa is devoid of villi.
 Drugs are in form of suppositories, gel, dry powders.
EX: Insulin, calcitonin
ADVANTAGES:
 Reduced proteolytic degradation.
 Improved systemic bioavailability with co-administration of
absorption enhancers.
EX: surfactants
 Large dose can be administered.
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38. OCULAR ROUTE
 In this route enkephalins, thyrotrophin releasing hormones,
luteinizing hormones ,glucagon and insulin are administered
BUCCAL ROUTE
 Mucoadhesive dosage forms can be used for buccal route.
 Adsorption enhancers like salicylates or a surfactant is used for
protein and peptide delivery through buccal route.
Example:
 Oxytocin , vasopressin , insulin, are reported to be absorbed
through buccal mucosa . And adhesive gel, patches , tablets are
used.
 Insulin is absorbed through buccal mucosa in the presence of
sodium glycolate.
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39. The drugs are absorbed through oral mucosa mainly through the
non-keratinized regions.
ADVANTAGES:
 It can be attached or removed without any discomfort and pain.
 Well acceptability by patients.
 Drugs are absorbed rapidly.
DISADVANTAGES:
 Administration time is limited.
 Drug loss by accidental swallowing.
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40. Nasal route of administration
o The nasal route has been employed for producing local action on the
mucosa which is more permeable compared to oral mucosa.
o Nasal absorption is through passive diffusion.
o EX: Insulin, human growth hormone.
ADVANTAGES:
o Rapid onset of action
o First pass metabolism can be avoided
o Better drug absorption
DISADVANTAGES:
o Long-term usage causes toxicity.
o Size of proteins and peptide drugs reduces systemic
bioavailability.
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41. PROTEIN FORMULATIONS
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• Protein sequence modification (site directed
mutagenisis)
• PEGylation
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• Proteinylation
• Microsphere encapsulation
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• Formulating with permeabilizers

42. PEGYLATION
o PEG is a non-toxic, hydrophilic, FDA approved, uncharged
polymer.
o Increases in vivo half life.
o Decreases immunogenicity.
o Increases protease resistance.
o Increases stability.
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CH-CH-CH-CH-CH-CH-CH-CH-CH-CH
||||||||||
OHOHOHOHOHOHOHOHOHOH
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43. PROTEINYLATION
o Attachment of additional or secondary (non-immunogenic) proteins for in
vivo protection.
o Cross-linking with Serum Albumin.
o Increases in vivo half life.
o Cross-linking or connecting by protein engineering with antibody
fragments.
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Protein drug
scfc (antibody)

44. FORMULATION WITH PERMEABILIZERS
o Salicylates (aspirin)
o Fatty acids
o Metal chelators (EDTA)
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45. Stability testing
The capability of a particular formulation in a specific container/closure system to remain within its
physical, chemical, microbiological, toxicological and protective specifications.
Evaluates the effect of environmental factors on the quality of the a drug substance or a formulated
product which is utilized for prediction of its shelf life, determine proper storage conditions.
o General
o Selection of Batches
o Container Closure System
o Specification
o Testing Frequency
o Storage Conditions
o Stability Commitment
o Evaluation
o Statements/Labelling
o On-going Stability Studies
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46. Conclusion
o Protein and peptide based pharmaceuticals are rapidly becoming
a very important class of therapeutic agents and are likely to
replace many existing organic based pharmaceuticals in the very
near future.
o Peptide and protein drugs will be produced on a large scale by
biotechnology processes and will become commercially
available for therapeutic use.
o Their need in the clinical & therapeutic regions has intensified
the investigation for their convenient & effective delivery
through noninvasive system.
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