CH 2: Drugs & the Body Flashcards
absorption
- what happens to a drug from the time it enters the body until it enters the circulating fluid
- IV administration causes the drug to directly enter the circulating blood
active transport
movement of substances across a cell membrane across the concentration gradient
chemotheapeutic agents
synthetic chemicals used to interfere w/ the functioning of foreign cell populations
critical concentration
the amount of a drug needed to cause a therapeutic effect
distribution
movement of a drug to body tissues
enzyme induction
process by which the presence of a chemical that is biotransformed by a particular enzyme system in the liver causes increased activity of that enzyme system
excretion
- removal of a drug from the body
- primarily occurs in the kidneys; can also occur through skin, lungs, bile, or feces
first-pass effect
phenomenon in which drugs given orally are carried directly to the liver after absorption, where they may be largely inactivated by liver enzymes before they can enter the general circulation
glomerular filtration
passage of water & water-soluble components from the plasma into the renal tubule
half-life
time it takes for the amount of drug in the body to decrease to 1/2 of the peak level it previously achieved
hepatic microsomal system
liver enzymes tightly packed together in the hepatic intracellular structure, responsible for the biotransformation of chemicals, including drugs
loading dose
use of a higher dose than that which is usually used for tx to allow the drug to reach the critical concentration sooner
passive diffusion
movement of substances across a semi-permeable membrane w/ the concentration gradient
pharmacodynamics
how the drug affects the body
pharmacogenomics
study of genetically determined variations in the response to drugs
pharmacokinetics
how the body acts on the drug
placebo effect
if a person perceives a drug will be effective, the drug is more likely to actually be effective
receptor sites
specific areas on cell membranes that react w/ certain chemicals to cause an effect w/in the cell
selective toxicity
property of a chemotherapeutic agent that affects only systems found in foreign cells w/o affecting healthy human cells
agonists
drugs that interact directly w/ receptor sites to cause the same activity natural chemicals would cause at that site
competitive antagonist
drugs that react w/ receptor sites to block normal stimulation, producing no effect
noncompetitive antagonist
drugs that react w/ receptor sites to prevent reaction of another chemical w/ a different receptor site
vasoconstriction
constricted blood vessels
cross-tolerance
resistance to drugs w/in the same class
