Simple Pharmanotes

  Passive Diffusion Also called non-ionic diffusion , it is the major process for absorption of more than 90% of the drugs.  The driving force for this process is the concentration or electrochemical gradient . It is defined as the difference in the drug concentration on either side of the membrane. Drug movement is a result of the kinetic energy of molecules. Since no energy source is required, the process is called passive diffusion.   Passive diffusion is best expressed by Fick's first law of diffusion which states that the transfer of drug molecules takes place from a region of higher concentration to lower concentration until equilibrium is attained and that the rate of diffusion is directly proportional to the concentration gradient across the membrane.  It can be mathematically expressed by the following equation: where, dQ/dt = rate of drug diffusion (amount/time). It also represents the rate of appearance of drug in blood D = diffusion coefficient of the ...

  Definition: Movement of drug molecules from site of administration to systemic circulation in the unchanged from. The rate and extent at which the drug gets absorbed determines its therapeutic success rate. Major routes of Drug Administration: The Enteral Route: This includes peroral i.e. gastrointestinal, sublingual/buccal and rectal routes.  The GI route is the most common route of administration. The Parenteral Route: This  includes all routes of administration through or under one or more layers of skin.  In case of intravenous route as drug is being poured directly in blood there is no question of absorption but,, it is necessary for extravascular parenteral routes like the subcutaneous and the intramuscular routes. 3. The Topical Route: This includes skin, eyes or other specific membranes.  The intranasal, inhalation, intravaginal and transdermal routes may be considered enteral or topical according to different definitions. Gastrointestinal Absorption o...

  Important Definitions. Biopharmaceutics: It is the branch of pharmacy that deals with the study of factors influencing the rate and amount of drug that reaches the systemic circulation and use of this information to optimize the therapeutic efficacy of the pharmaceutical products. Absorption: Movement of unchanged form of  drug molecule from site of administration to the systemic circulation is called  absorption. 3)       Bioavailability: Rate and extent of drug molecules reaching systemic circulation in intact form. 4) Drug Disposition: Collective phenomenon of drug distribution and elimination of drug following absorption is called Drug Disposition. 5) Drug Distribution: The movement of drug molecules across the body compartments (Blood and extravascular tissues) is called drug distribution. 6) Drug Elimination: It is defined as the process of removal of drug from body termination of its action, it can be achieved by two processes as, Biotransformation...

  Super Centrifuge. Centrifuge: The equipment used for the process of centrifugation is called a Centrifuge. The centrifuges are of two types as following, Sedimentation centrifuge:L It is a centrifuge that produces sedimentation of solids based on the difference in the densities of two or more phases of the mixture.  Filtration centrifuge:  It is a centrifuge in which solids pass through the porous medium based on the difference in the densities of the solid and liquid phases. Super Centrifuge.   Super Centrifuge is a continuous centrifuge used for separating two immiscible liquid phases. Principle:   It is a sedimentation centrifuge.  The separation is based on the difference in the densities between two immiscible liquids.  Centrifugation is done in the bowl of a small centrifuge.  During centrifugation, the heavier liquid is thrown against the wall, while the lighter liquid remains as an inner layer.  The two layers are simul...

  Centrifuge: The equipment used for the process of centrifugation is called a Centrifuge. The centrifuges are of two types as following, Sedimentation centrifuge:L It is a centrifuge that produces sedimentation of solids based on the difference in the densities of two or more phases of the mixture.  Filtration centrifuge:  It is a centrifuge in which solids pass through the porous medium based on the difference in the densities of the solid and liquid phases. Non-Perforated Basket Centrifuge. Principle:   This is a sedimentation centrifuge.  The separation is based on the difference in the densities of solid and liquid phases without a porous barrier.  The bowl contains a non-perforated side-wall.  During centrifugation, solid phase is retained on the sides of the basket, while the  liquid remains at the top, which is removed by a skimming tube. Construction:   It consists of a basket, which may be made of steel or any other sui...