DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS

DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS

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  DIFFUSION PRINCIPLES SOLUBILITY PHYSICALPHARMACEUTICS-I DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS
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  DIFFUSION  “ Aphysical process that refers to the net movement of molecules from a region of high concentration to lower concentration under the influence of concentration gradient.”
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  DIFFUSION  “Mass transferof individual molecules of a substance caused by random molecular motion, associated with a driving force such as the concentration gradient”
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  USE OF DIFFUSIONCONCEPT  Diffusion phenomena applied in pharmaceutical sciences include:  1. Release of drug from dosage form  2. Ultrafiltration, microfiltration, dialysis, hemodailysis.  3. Permeation & distribution of drug in living tissues  4. Estimation of molecular weight of polymers  5. Prediction of absorption & elimination of drug.
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  USE OF DIFFUSIONCONCEPT
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  TYPES OF DIFFUSION 1. Passive diffusion:  Net moment of material from an area of high concentration to an area of low concentration.  The difference between high and low concentration is termed as concentration gradient.  Diffusion will continue until the gradient has been eliminated.
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  TYPES OF DIFFUSION 1. Passive diffusion:  It is the most important mechanism for passage of drugs through membranes.  When drug release in body after that it start to diffuse in region of higher concentration to lower concentration across the plasma membrane of the cell.
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  TYPES OF DIFFUSION 2. Facilitated (carrier mediated) diffusion:  It is moment of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane.
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  TYPES OF DIFFUSION 3. Active transport:  Movement of molecules across a membrane from a region of lower concentration to higher concentration, against the concentration gradient.
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  TYPES OF DIFFUSION 4. Filtration:  Movement of solvent or solute molecules, influenced by hydraulic pressure.
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  LAWS OF DIFFUSION It is Given by Adolf Fick in 1856.  The simplest description of diffusion is given by Fick's laws, which were developed by Adolf Fick in the 19th century:  The molar flux due to diffusion is proportional to the concentration gradient  1. FICK’S FIRST LAW OF DIFFUSION  2. FICK’S SECOND LAW OF DIFFUSION: Adolf Fick
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  FICK’S FIRST LAWOF DIFFUSION  According to Fick’s law of diffusion,  “The molar flux due to diffusion is proportional to the concentration gradient”.  The rate of change of concentration of the solution at a point in space is proportional to the second derivative of concentration with space.
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  FICK’S SECOND LAWOF DIFFUSION  Prediction of change in concentration along with time due to diffusion.  “Change in concentration with time in a particular region is proportional to the change in concentration gradient at that point in the system.”
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  LAWS OF DIFFUSION The difference in the concentration of a substance between two areas is called the concentration gradient .  The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse.  The direction of diffusion is said to be 'down' or 'with' the concentration gradient.
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  LAWS OF DIFFUSIONAPPLICATIONS  Fick’s law is applicable for two miscible liquids when they are brought in contact and diffusion takes place at a macroscopic level.  Pharmaceutical application in drug release and absorption of medicine to provide pharmacological action  Applications in food industries.  Fabrication of semiconductor: Diffusion equations from Fick’s law are used to fabricate integrated circuits.