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29 Cards in this Set
- Front
- Back
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Passive Diffusion |
-Majority of drug movement through tissue fluid or membrane barriers -The random movement of drug molecules from an area of high concentration to an area of lower concentration -no active cellular energy expended |
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Concentration Gradient |
Moving down - high concentration to low |
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Phospholipids |
-A molecule with phosphate groups and fatty acid components -Primarily composes cell membranes |
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Equilibrium |
-In diffusion, the number of molecules at Point A and Point B are the same -Diffusion does not stop at this point, but no net diffusion can be detected |
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Facilitated Diffusion |
-Passive transport mechanism accross cell membranes that involves a special "carrier molecule" located in the cellular membrane -No energy expended by the cell to move molecules -The direction of drug movement is determined by the concentration gradient |
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Carrier molecule |
Usually a protein floated among the phopholipid molecules in the cell membrane has a specific site to which a drug molecule can attach |
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Active Transport |
-Involves a specialized carrier molecule -The cell expends energy -The drug molecules an move against the concetration gradient -Don't stop when equilibrium is reached, but can result in large accumulation of drug molecules within a cell or body compartment |
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Pinocytosis |
-Form of active transport -Involves physically engulfing the drug molecule by the cell membrane -"Cell Drinking" -Involves small invagination fomring the cell membrane -Slow mechanism for cell transport |
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Phagocytosis |
-Form of active transport -Involves physically engulfing the drug molecule by the cell membrane -"Cell eating" -Involves most or all of the cell -Slow mechanism for cell transport |
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Lipophilic |
-"Fat loving" -Drugs molecules must to move accross membrane - dissolves in fat or oil -Nonpolarized and nonionized molecules |
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Hydrophilic |
-"Water loving" -Molecules that do not readily dissolve in fat or oil -Dependent upon carrier mediated transport -Polarized or ionized |
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Pharmacokinetics |
The study of how physiologic or drug characteristics affect drug movement and concetrations within the body |
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Absorption |
The movement of drug molecules from the site of administration o the systemic circulation. |
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Bioavailablility |
-the degree to which an administered drug is absorbed -If 100% of the drug administered makes it to the systemic circulation = 1 or 100% -IV has highest F -Followed by IM, then PO and SQ |
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Extracellular Fluid |
-Fluid outside of the cells -Drugs injected SQ or IM are deposited here, and then must diffuse through to reach capillaries to be absorbed |
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Acidic |
-Refers to the conditions in which many free H+ ions are available in the liquid and the liquid has a "low" pH -pH of 1,2,3 |
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Basic/Alkaline |
-High pH wouldhave few available H+ ions in the liquid -pH of 10,11,12 |
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Acid drug |
A drug whose chemical nature causes it to release a H+ ion into the liquid environment and become more ionized (hydrophilic) as the drug is place in increasing alkaline environments EX: carbonic acid |
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pKa |
The pH at which the ratio of ionized to nonionized molecules exists as a 1:1 ratio Equal amounts of both ionized and nonionized forms |
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Ion Trapping |
If a drug molecule in a lipophilic form passes through a cellular membrane and enters a body compartment whose pH results in a significant shift to hydrophilic form, the drug molecule may not be ablet oe xit the compartment thorugh the cellular membrane because of its new hydrophilic form Is used to remove excessive drug or absorbed toxic agents through kidneys |
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Dissolution |
=Dissolving -Critical step in the absorption of drugs given by mouth |
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Gastric Motility |
Stomach contractions that mix stomach contents and move the contents fromt he stomach into the small intestine -increased = may have drug reach SI and be absorbed sooner than normal |
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Intestinal Motility |
The mixing and propulsive contractions of the intestine -increased = not dissolved -decreased = complete absorption, even those not intended to be absorbed |
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heaptic portal system |
conducts the blood from the intestine to the liver where the materials from the intestine can be acted upon the liver |
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Xenobiotics |
Foreign substances (liver can recognize and remove and prevent certain drugs from reaching the rest of the body) |
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First-Pass Effect |
The phenomenon by which the liver removes so much of the drug that very little reaches the systemic circulation Drugs with extensive re not recommended PO |
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Perfusion |
The extent to which a tissue is supplied with blood -Well = absorb injected drugs much quicker -Fat is poor -Skeletel is better == IM are absorbed more quickly than SQ |
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Vasoconstriction |
Reducing blood flow to the area Occurs in cold temperatures -Reduces perfusion, decreases rate of absorption of SQ injected drugs |
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Vasodilation |
Dilation of blood vessles -Enhances perfusion of tissues and therefore increases drug absorption in SQ tissue and in muscle -increase in body temp or drugs (such as alcohol) |
