protein drug delivery systems2
Post on 05-Jul-2015
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Presented by G.Ramya
Mpharm(phceutics)256212886041
MRCP
Under the guidance ofMrs.Yasmin Begum
Mpharm(PhD)
Proteins and Peptides drug delivery system
Contents
Protein & Peptides Structure of protein Classification of protein Stability problems Marketed formulations Conclusion References
Proteins: These are 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 α-amino acids. peptide < 50 amino acids
Protein & Peptide
Each peptide or protein molecule is a polymer chain with α aminoacids linked together in a sequential manner by peptide bonds.
The peptide chains in a protein molecule are often folded into a specific three dimensional structure to fulfill a certain biological function.
The functional groups on each of the aminoacids and the sequence of the aminoacids in the peptide chains determine the conformation of the protein.
STRUCTURE OF PROTEIN
Based on their conformation proteins are classified as
Fibrous proteins Eg: collagen, keratin, elastin.
Globular proteins: insulin
STRUCTURE OF PROTEIN
There are four types.
Primary structure- The amino acid sequence.
Secondary structure- Regularly repeating local structures
stabilized by hydrogen bond.
Tertiary structure-Three dimensional structure of polypeptide
Quaternary structure-The structure formed by several protein
molecules (polypeptide chains).
STRUCTURE OF PROTEIN
Lactate Dehydrogenase: Mixed α /β
Immunoglobulin Fold: β
Hemoglobin B Chain: α
Protein Structure
Transport and storage of small molecules.
Coordinated motion via muscle contraction.
Mechanical support from fibrous protein.
Generation and transmission of nerve impulses.
Enzymatic catalysis.
Immune protection through antibodies.
Control of growth and differentiation via hormones.
FUNCTIONS
Classification of Proteins
According to their biological roles Enzymes – Catalyses virtually all chemical reactions i.e.
6GDH Transport proteins i.e. Haemoglobin of erythrocytes Contractile or Motile proteins i.e. Actin and Myosin Structural proteins i.e.Collagen in bones Defense proteins i.e. Immunoglobulins and Antibodies Regulatory proteins i.e. insulin Nutrient and storage proteins i.e. Ovalbumin
Management of illness through medication is entering a new era in which a growing number of biotechnology produced peptide and protein drugs are available for therapeutic use.
Ailments that can be treated effectively by this new class of therapeutic agents include cancers, memory impairment, mental disorders, hypertension.
Protein and Peptide drugs
Short biological half-life
Very large and unstable molecules.
Structure is held together by weak noncovalent forces.
Easily destroyed by relatively mild storage conditions and
gastric juices.
Hard to obtain in large quantities.
Disadvantages
Elimination by B and T cells
Proteolysis by endo/exo peptidases
Small proteins filtered out by the kidneys very quickly
Unwanted allergic reactions may develop (even toxicity)
Loss due to insolubility/adsorption
First-pass elimination in liver
Problem with Proteins (in vivo – in the body)
Physical instability Chemical instability Denaturation Deamidation Adsorption Oxidation and reduction Aggregation Proteolysis Precipitation Disulfide exchange Racemization β-elimination
Protein instabilities
Denaturation refers to any nonproteolytic modification of the unique structure of a native protein that affects definite changes in physical, chemical and biological properties.
Denaturation leads to rearrangement and loss of quarternary and tertiary structure and the hydrophobic and hydrogen bonds are broken.
Conditions include: Solvent changes pH change Alteration in ionic strength Temperature rise
Denaturation
Category Mechanism Examples
Polar and protic chemicals
Surfactants
Disrupt H-bonds
Hydrophobic disruption and charge group separation
Urea, Guanidine HCL, Alcohol, Acetic acid
Sodium dodecyl sulphate, Polyethylene glycol, Dodecyl ammonium chloride
Common Protein Denaturing agents
Proteins and peptides tend to absorb at interfaces such as air-water and air-solid.
This leads to conformational rearrangement which may cause loss or change in the biological activity.
It posses limitations with the drug delivery systems where protein content of formulation may remain adhered to the containers or drug delivery devices.
Overcome by addition of surfactants such as Pluronic F68 and Tween80.
Adsorption
Mechanism of protein aggregation involves protein denaturation and noncovalent association via hydrophobic residues.
Aggregation on a macroscopic scale leads to precipitation. Conditions favour include: Large air-water interface Agitation of the solution Presence of large headspace within the confines of
container. Increase in thermal motion of the molecules due to
agitation.
Aggregation and Precipitation
It involves the hydrolysis of the side chain amide linkage of an aminoacid residue leading to formation of free carboxylic acid.
Asparagine, glutamine, serine, glycine. Human growth harmone(hGH), bovine growth
harmone(bGH), prolactin, insulin, lysozyme and secretin. It leads to lowering of biological activity and alteration in
function.
Deamidation
Deamidation of L-Asparagyl residue
Methionine, cysteine, tryptophan and tyrosine. Commonly occurs during isolation, synthesis and storage of
proteins. Leads to loss in biological activity as observed in calcitonin,
corticotrophin, gastrin. Oxidising agents like hydrogen peroxide, dimethylsulphoxide
and iodine oxidise met to Met-sulphoxide.
Methionyl residue Methionyl sulfone residue
Oxidation
Hydrolysis of peptide bonds within the polypeptide or protein destroys or reduces the activity.
It may occur on prolonged exposure of proteins to extreme pH range, high temperature or proteolytic enzymes.
Bacterial contamination is the most common source of proteases.
Proteolysis
Disulfide bonds may break and reform with incorrect pairings which results in alteration of 3-dimensional structure followed by change in biological activity.
HSR’ + R-S-S-R ---- > R-S-S-R’
Peptide chain with more than one disulfide can enter into disulfide exchange reactions leading to scrambling of disulfide bridges and thereby change in alteration.
Disulfide Exchange
Alteration of L-aminoacids to D,L-mixtures. Except gly, all the mammalian aminoacids are chiral at the
carbon bearing chain and are susceptible to base catalysed racemization.
This reaction can be catalysed in neutral and alkaline media by thiols which may arise due to hydrolytic clevage of disulfides.
Racemization
The mechanism is similar to racemization which forms a carbonium intermediate.
Higher elimination rate under alkaline conditions leads to loss of biological activity.
Cys, Lys, Phe, Ser, and Thr
β-elimination
Photodegradation
Tryptophan, Tyrosine and Cysteine are susceptible to nonionizing radiation such as UV light.
Photoionisation can be either through direct interaction with aminoacid or indirectly via various sensitizing agents such as oxygen.
Photodegradation products include: S-S bond fission Conversion of tyrosine to DOPA Conversion of tryptophan to kynurenine and n- formyl-
Kynurenine.
Excipients Functions Examples
Surfactants Prevent denaturation and aggregation
Polysorbate 20, 80
Albumin Antiaggregatory Serum albumin
Sugars Stabilize protein against denaturation
Mannitol, propylene glycol, Sucrose, Lactose
Cryoprotectants Stabilize protein against very cold condition
Sugars, Amino acids, Amines, polyols, Salts
Commonly used excipients For solving physical and chemical stability problems
Osmolarity agent Stabilize pH Phosphate, Citrate Buffer
Preservatives Prevent from
microbes
Phenol, benzyl
alcohol
Antioxidants Prevent oxidation Ascorbic acid, sulphites, cysteine,
chelating agent
Solubility
enhancing agent
Increase solubility
of protein
Amino acids,
detergent,
cyclodextrin
Lyoprotectants Stabilize protein during freeze drying
Sugars
Applications
Protein/peptide drugs Biomedical applications
CVS activeAngiotensin 2 antagonistBradykininCaptopril
Lowering blood pressureImproving peripheral circulationHeart failure management
CNS activeCholecystokininΒ-endorphin
Suppressing appetiteRelieving pain
Applications
GI-activeGastrin antagonistPancreatic enzymes
Reducing secretion of gastric acidDigestive supplement
ImmunomodulatingBursinCyclosporinInterferon
Selective B-cell differentiatingharmoneInhibits functions of T-lymphocyteEnhancing activity of killer cells
Metabolism modulatingInsulinVassopressin
Treating diabetes mellitusTreating diabetes insipidus
Product Formulation Route Indication
Metrodin FSH 75 IU i.m. Induction of ovulation
Pergonal FSH and LH i.m. infertility
Profasi HCG i.m. Infertility
Elspar Asparginase i.m. i.v. Leukemia
Glucagon Glucagon i.m. i.v. s.c. Hypoglycemia
Acthar Corticotropin i.m. i.v. s.c. Hormone Deficiency
MARKETED PROTEINS IN FREEZE DRIED FORMULATIONS
Product Formulation Route Indication
Pitressin 8-Arginine Vasopressin
i.m. s.c. Post operative abdominal distension
Lupron Leuprolide s.c. Prostatic cancer
Syntocinon Oxytocin i.m. i.v. Labour induction
Sandostatin Octreotide s.c. Intestinal tumour
Calcimar Salmon calcitonin
s.c. hypercalcemia
MARKETED PEPTIDES IN READY TO USE FORMULATIONS
SUSTAINED RELEASE DOSAGE FORMS
Product Formulation Route Indication
Lupron Leuprolide i.m. Prostatic cancer
H.P.Acthar gel
ACTH i.m. s.c. Antidiuretic
Pitrressin tannate in oil
Vasopressin tannate
i.m. Endocrine cancer
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.
Peptide and protein drugs will be produced on a large scale by biotechnology processes and will become commercially available for therapeutic use.
Conclusion
This poses an urgent challenge to the pharmaceutical industry to develop viable delivery systems for the efficient delivery of these complex therapeutic in biologically active form.
Much work needs to be done on the development of viable delivery systems for non parenteral administration to make peptide and protein pharmaceuticals commercially viable and therapeutically useful.
Conclusion
REFERENCES
Controlled drug Delivery Concepts and Advances By Vyas, Roop Khar, Proteins and Peptides Delivery Considerations Page No: 503-511.
Advances in Controlled and Novel Drug Delivery By N.k.Jain, Oral delivery of protein and peptides Page no: 232-235.
Novel Drug Delivery System By Yie.W.Chein, Systemic Delivery of Peptide based pharmaceuticals Page no:631-637.
Drug Stability Principles and practices By J.Carstensen, Stability of Polypeptides and Proteins Page no:560-572
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