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51 Cards in this Set
- Front
- Back
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Define Pharmokinetics
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The study of drug movement throughout the body
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The cell membrane is composed of what?
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a double layer of molecules known as phospholipids
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Name two ions which can pass through channels or pores
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Na+ and K+
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Define transport system. Is it selective or nonselective?
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A system which transports drugs from one side of a cell membrane to another. Only carries drugs with a particular structure.
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What type of drug can penetrate a cell membrane?
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Lipophilic or lipid-soluble
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List two types of non-lipid soluble drugs?
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Polar molecules and most ions
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Define polar molecule. They dissolve well in what solvent?
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Molecules which have an unequal or uneven distribution of electrons yet no net charge.
Water |
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Define ion
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Atoms which have a net electrical charge
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An acid tends to ionize in what type of environment? A base tends to ionize in what type of environment?
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Acid ionizes in Base
Base ionizes in Acid |
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Explain ion trapping or pH partitioning
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When there is a pH gradient between two sides of a cell membrane, acidic drugs will ionize and stay on the basic side. Basic drugs drugs will ionize and stay on the acidic side. Ionized drugs do not cross cell membranes.
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Define Absorption
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The movement of drug from its site of administration into the blood.
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Rapidly dissolving drugs will have what type of onset?
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Rapid
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An increased surface area for absorption will cause absorption to increase or decrease?
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Increase
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Drugs are absorbed more rapidly in areas where blood flow is what?
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High
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What types of drugs are absorbed rapidly through the cell membrane?
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Lipophilic or lipid-soluble
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Delayed gastric emptying may delay the absorption of a drug meant to be absorbed where?
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Intestines
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Parenteral drugs refer to routes of administration where?
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Outside the GI Tract
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What is the rate of absorption for intravenous administration?
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Instantaneous
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What is the barrier to intramuscular absorption?
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Capillary wall
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What types of drugs are absorbed from intramuscular and subcutaneous sites?
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Poorly soluble drugs (water-soluble)
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Which route is the safest for drug administration?
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Oral
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Define chemically equivalent
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Drugs contain the same amount of the identical chemical compound
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Define bioavailability
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Drugs contain the same amount of the identical chemical compound and are absorbed at the same rate and to the same extent.
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Where are enteric-coated drugs meant to dissolve?
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Intestine
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What are sustained-release capsules utilized?
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Maintain a steady release of the drug all day
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What is the most common mechanism by which drugs enter a cell?
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Direct penetration of the membrane
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Should enteric-coated drugs be crushed? why or why not?
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No, the drug would interact with stomach acids
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What does the p-glycoprotein do?
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It is a transmembrane protein which transports drugs out of the cells back into the blood stream or into lumens such as renal tubules or intestinal lumens
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What is a quaternary ammonium compound?
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It is a compund with at least one nitrogen atom which has 4 bonds rather than 3 bonds. It has a + charge & is unable to cross most membranes
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What is the blood-brain barrier? Name 2 ways drugs enter the brain?
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The capillaries of the brain dono't have gaps between the cells of the capillaries.
Drugs must pass thru the cell membrane or be transported by a transport system |
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The cytochrome P450 system refers to a family of enzymes which does what?
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Metabolize drugs.
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Kidneys are unable to excrete what type of drugs?
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Highly lipid-soluble
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Define prodrug
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An inactive compound which can be converted into an active drug
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Define the first-pass effect
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Blood passes thru the liver before reaching the systemic circulation
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How does cigarette smoking affect the rate of drug metabolism?
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Increases
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If a drug binds to albumin and displaces another drug from the site, what happens to the serum concentration of the drug displaced?
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Increases
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At what age does an infant's liver develop into its full capacity?
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One Year
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The most important organ for drug excretion is what?
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The Kidneys
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Which drugs remain in the urine for excretion?
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Polar and ionized drugs
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Define enterohepatic circulation?
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Drugs excreted in the bile are reabsorbed into the portal blood
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What type of drug easily enters the breast milk?
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Lipid-soluble or lipophilic
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Define the minimum effective concentration (MEC)
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The plasma drug level at which a drug has a therapeutic effect
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Define toxic concentration
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The plasma drug level at which toxic effects begin
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Define therapeutic range
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The range of plasma drug levels that fall between the MEC and the toxic concentration
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Define duration
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The length of time the drug is in the therapeutic range
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Define half-life
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The time required for the amount of drug in the body to decrease by 50%. For example if the half life is one day, in 1 day, 50% is left
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How many half-lives does it take to clear a drug from the body?
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4 half-lives
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Define plateau. What is the relationship between absorption and elmination?
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Steady concentration of drug reached after repeated doses.
Absorption = Elimination |
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Why are loading doses given?
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To shorten the time to plateau
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Why are maintenance doses given?
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To continue plateau
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What type of drugs cross the placenta?
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Lipid-soluble or lipophilic
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