DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS
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This document discusses diffusion principles that are important in biological systems and pharmaceutical sciences. It defines diffusion as the net movement of molecules from an area of high concentration to low concentration down a concentration gradient. The document outlines different types of diffusion including passive, facilitated, active, and filtration. It also describes Fick's Laws of Diffusion, which state that the rate of diffusion is proportional to the concentration gradient. Fick's laws are applied to understand processes like drug release from dosage forms and distribution in tissues.
DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS
- 1. DIFFUSION PRINCIPLES SOLUBILITY PHYSICAL PHARMACEUTICS-I DIFFUSION PRINCIPLES IN BIOLOGICAL SYSTEMS
- 2. DIFFUSION “ A physical process that refers to the net movement of molecules from a region of high concentration to lower concentration under the influence of concentration gradient.”
- 3. DIFFUSION “Mass transfer of individual molecules of a substance caused by random molecular motion, associated with a driving force such as the concentration gradient”
- 4. USE OF DIFFUSION CONCEPT 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.
- 5. USE OF DIFFUSION CONCEPT
- 6. 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.
- 7. 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.
- 8. 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.
- 9. 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.
- 10. TYPES OF DIFFUSION 4. Filtration: Movement of solvent or solute molecules, influenced by hydraulic pressure.
- 11. 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
- 12. FICK’S FIRST LAW OF 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.
- 13. FICK’S SECOND LAW OF 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.”
- 14. 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.
- 15. LAWS OF DIFFUSION APPLICATIONS 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.