Biodegradable Polymer: Introduction

Definition: A polymer that are degradable in-vivo, either by enzymatically or non-enzymatically, to produce biocompatible or nontoxic by-products.
Biodegradation: A natural process by which organic chemicals are converted to simpler compound through elemental cycles such as the carbon, nitrogen and Sulphur cycles.
  • Microorganism plays a central role in the biodegradation process.
  • Bio degradation occur in two steps:
    • 1st step From Fragmentation of the polymer into lower molecules:
      • By abiotic reaction i.e. oxidation, photo degradation, hydrolysis.
      • By biotic reaction i.e. degradation by microorganism.
    • 2nd step: Bio Assimilation of the polymer fragments
  • Biodegradability of the polymer depends on
    • Its origin & chemical structure & also environmental condition
  • Biodegradable polymers are capable of being cleaved into biocompatible by-product through chemical or enzyme catalyzed hydrolysis
  • Advantages of Biodegradable polymer:
    • Provide constant controlled rate for long time
    • Metabolized by-product is non-toxic and easily remove by body extraction
    • Dose dumping not exhibit
    • No surgical removal of implanted device
    • It can be used for targeted drug delivery
  • Disadvantages of Biodegradable polymer:
    • Burst effect at initial dose
  • Mechanism of drug release from Biodegradable polymer:
    • This polymer degrades within body as a result of natural biological process.
    • Most biodegradable polymer degrades through hydrolysis process.
    • Biodegradable polymer undergo degradation in four steps
      • Hydration
      • Strength loss
      • Loss of mass Integrity
      • Mass loss
    • Hydration:
      • It is variable in rate, degree and is dependent upon the nature of polymer.
      • In this step, disruption of Vander Waal’s bond or hydrogen bond is broken.
    • Strength loss
      • In this step, the covalent bond is broken.
      • The strength loss rate is dependent upon the temperature, pH and degree of crystallinity. 
      • More crystalline species may be expected to maintain their strength for longer period of time compare to those of amorphous.
    • Loss of mass Integrity
      • In this step more and more covalent bond is broken and polymer is degraded to a molecular weight level.
      • This step is more important in degradation.
    • Mass loss:
      • This step involves the complete removal of Polymer from the tissue.
      • It occurs either by solubilization of small units or by phagocytes
      • Sometime the polymer mass may be removed from site, without actual reduction in their length, thought  solubilization that involve side chain modification
  • Factors affecting Biodegradation of polymer:
    • Chemical structure
    • Chemical decomposition
    • Present of ionic groups
    • Molecular weight
    • Morphology
    • Site of implantation
    • Mechanism of hydrolysis
    • Hydrophilicity
  • Classification of biodegradable polymers:
  • Natural polymer: 
    • Guar gum, Acacia, Karaya, Tragacanth, Xanthan, Albumin, pectin, starch, gellen etc.
    • Prime advantage include biodegradation in natural products, easy availability, absense of toxicity and antigenicity
    • Albumin micro spheres have been employed to deliver many drugs like hematoprophyrin, sulphadiazine, and prednisolone, 5-flurouracil
  • Semisynthetic polymer:
    • Cellulose derivatives:
      • Cellulose is insoluble in water and most commom solvents
      • Have poor solubility
      • Chemically modified cellulose have a good properties, 
      • It include; CMC, MC, HEC, HPMC etc
    • Collagen:
      • Have good biocompatibility, low toxicity, degradation on implantation and gelling ability
    • Gelatin:
      • It has been employed as matrix and coating material.
      • It offers advantage like low antigen profile ,poor binding to drug, low temp
      • So reduce to chances of drug degradation
    • Chitin and chitosan:
      • Chitosan has been administered as excipients for oral drug formulations.
      • It is used as direct tableting agent, mask bitter taste, disinyegrant & for coating.
      • Have good mucoadhesive, antimicrobial and controlled release properties
    • Dextran:
      • Synthesized from sucrose by certain lactic acid bacteria.
    • Alginate:
      • Alginate micro spheres have been used for oral delivery of vaccines.
      • They protect antigen/vaccine against degradation in G.I.T.
      • Have good gelling ability
    • Fibrinogen, Hyaluronic acid, Cyclodextrin

Comments

Post a Comment

Popular posts from this blog

PLANT LAYOUT FOR CAPSULE MANUFACTURING DEPARTMENT & MANUFACTURING PROCESS

Image
PLANT LAYOUT  FOR CAPSULE MANUFACTURING DEPARTMENT: ENVIRONMENT CONDITION FOR CAPSULE FILLING AREA Humidity:          Not more than 35% RH Temperature:    Not more than 25% Area of each room, position of equipments, washing, drying, and sanitary facilities must be in accordance with GMP. MANUFACTURING PROCESS: CHEMCAPS Limited is an India based young and dynamic organization engaged in the manufacture and export of 'empty hard gelatin capsules' under the brand name of 'Chemlock' for discerning customers around the globe. COMPOSITION                                     Gelatin                                     Water                                     Colorants                                     Opecifier (TiO2 Dyes and Other)                                     Preservative MANUFACTURING OF HGC SHELL: SFR-901 FULLY AUTOMATIC CAPSULE MACHINE: FEATURES OF SFR-901 Ø   The Safrroys SFR-901 mod
Keep reading

2. Extensive literature survey:

Image
Once the problem is formulated, a brief summary of it should be written down. It is compulsory for a research worker writing a thesis for a Ph.D. degree to write a synopsis of the topic and submit it to the necessary Committee or the Research Board for approval.   At this juncture the researcher should undertake extensive literature survey connected with the problem. For this purpose, the abstracting and indexing journals and published or unpublished bibliographies are the first place to go to. Academic journals, conference proceedings, government reports, books etc., must be tapped depending on the nature of the problem. In this process, it should be remembered that one source will lead to another. The earlier studies, if any, which are similar to the study in hand, should be carefully studied. A good library will be a great help to the researcher at this stage.
Keep reading

ANTIOXIDANTS: In Pharmaceutical Formulation

Image
Introduction: Chemically they are reducing agents. They oxidize themselves and prevent oxidation of API. A substance that inhibits oxidation is called antioxidants. The effectiveness of antioxidant can depend on the concentration used and pH of solution. Examples:  Ascorbic acid,  butylated hydroxy anisole (BHA),  butylated hydroxyl toluene (BHT) Oxidation is a chemical reaction involving the loss of electrons or an increase in oxidation state. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions. The following are some of the qualities of an ideal anti-oxidant: It should be readily soluble or dispersible in the medium. It should be effective in low concentration. It should be non-toxic. It should be non-irrita
Keep reading

Facebook Page

Knowledge of Pharma