Term
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Definition
| – Movement of molecules from one region to another as a result of a specific driving force |
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Term
| What are the fundamental physical concepts involved in mass transport? |
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Definition
| thermodynamics and kinetics principles |
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Term
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Definition
| – Energy change in a process in a particular direction |
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Term
| Thermodynamic systems have a tendency to go toward .... |
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Definition
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Term
| Thermodynamic reactions occur when... |
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Definition
| free energy of product is lower than free energy of reactants |
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Term
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Definition
| – Effect of time on a process or reaction. How much time would it take for a reaction to proceed |
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Term
| Why do I need to know about Mass transport? |
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Definition
• To understand how drug and formulations affect delivery system, absorption, bioavailability and pharmacological effect we have to know a few things
– Mechanism of drug transport
– Physiology of route of administration
– Effect of different conditions and pathological conditions |
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Term
| The effectiveness of a drug often depends on ... |
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Definition
| how much of the drug reaches its site of action. |
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Term
| What are 2 major categories of pharmaceutical transport system? |
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Definition
| Solute Transport and Solvent transport |
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Term
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Definition
| Movement of molecules across artificial or natural boundaries |
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Term
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Definition
| Movement of solvent across semipermeable membranes by osmosis |
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Term
| Based on the route, drug transport could be of two types, name those |
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Definition
| Paracellular transport & Transcellular transport |
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Term
| Define Paracellular Transport |
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Definition
| – Drug is transported between the cell-cell junction i.e. tight junctions. In this process, molecules do not cross the cell membrane nor enter cells in their path |
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Term
| Describe what molecules can utilize paracellular transport |
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Definition
| – Drug molecules that are smaller in size than the junction usually pass through the paracellular route |
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Term
| Define Transcellular transport |
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Definition
| – Drug molecules pass through the cells. |
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Term
| During transcellular transport molecules must pass through what? |
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Definition
| The molecules have to cross the cell membrane in their entry to and exit out of the cells |
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Term
| What are the 4 basic mechanisms of transport? |
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Definition
– Passive transport
– Facilitated transport
– Active transport
– Vesicular transport |
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Term
| Define Vesicular transport and explain why it is different from other transport mechanisims |
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Definition
| allows transport of macromolecules such as proteins or particles such as liposomes, nanoparticles. The other 3 mechanisms are used for small molecules |
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Term
| Describe diffusion of passive transport |
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Definition
| Random Brownian motion from a region of high concentration to a region of low concentration |
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Term
| Is energy required for passive transport? |
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Definition
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Term
| Does passive transport require a concentration gradient? |
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Definition
| Yes, Concentration gradient required. Equilibrium achieved when concentration is equal in both regions |
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Term
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Definition
| When molecules are transported by another liquid or gaseous medium e.g. Transport of oxygen, nutrients through blood |
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Term
| Define Facilitated Transport |
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Definition
| • Diffusion with the aid of a carrier where drug-carrier complex has higher permeability than drug alone |
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Term
| Does Facilitated transport used charged or uncharged ions? |
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Definition
| • Can occur with both charged or uncharged molecules |
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Term
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Definition
| • Movement of molecules against the concentration gradient – i.e. from a region of low concentration to a region of high concentration |
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Term
| Does Active transport require energy? If so where does it come from? |
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Definition
• Requires a source of energy
• Primary energy source – conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) |
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Term
| Is active transport saturated or unsaturated transport? |
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Definition
• Saturable transport (think Enzyme kinetics from Biochemistry)
• E.g. Cellular uptake of electrolytes and nutrients like:
– Transport of Na+ and K+ from extracellular to intracellular compartment |
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Term
| What type of transport is involved in the Absorption of Drugs ? |
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Definition
• Active transport is involved in the absorption of several drugs
• Systems appear to be specific to a particular chemical compound
– Anti-tumor agent 5-Fluorouracil transported by the pyrimidine transport system
– Methyldopa by the amino acid transporter |
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Term
| Define efflux proteins or efflux pumps. |
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Definition
| • As opposed to transporters that assist substrate entering the cells, there are transporters that pump substrate out of the cells |
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Term
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Definition
| is a phenomenon in which a single type of transporter (multidrug resistance, MDR transporters) recognizes and pumps many drugs with no apparent common structural similarities out the cells.• -Multiple drug resistance that develops in bacterial and cancer cells is the result of MDR transporter efflux |
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Term
| Define P (permeability)-glycoprotein |
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Definition
is one of the pumps or efflux proteins found in the membranes of bacteria and human cells.
• In humans, P-glycoprotein is found mainly in organs of digestion and excretion, where it appears to protect the body by eliminating toxic chemicals. Present in the brain for protection. |
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Term
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Definition
| Uptake of liquid molecules into the cell |
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Term
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Definition
| Uptake of colloidal particles and macromolecules up to a size of 100 – 200 nm |
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Term
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Definition
| Ingestion of larger molecules up to 5 um |
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Term
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Definition
| Efflux of synthesized proteins and metabolic waste products from the cell |
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