absorption
the process whereby a drug enters the circulatory system
addiction
a dependence characterized by a perceived need to take a drug to attain the psychological and physical effects of mood-altering substances
affinity
the strength by which a particular chemical messenger binds to its receptor site on a cell
agonist
drugs that bind to a particular receptor site and trigger the cell's response in a manner similar to the action of the body's own chemical messenger
allergen
substance that produces an allergic response
allergic response
an instance in which the immune system overreacts to an otherwise harmess substance
anaphylactic reaction
a severe allergic response resulting in immediate life-threatening respiratory distress, usually followed by vascular collapse and shock and accompanied by hives
angioedema
abnormal accumulation of fluid in tissue
antagonist
drugs that bind to a receptor site and block the action of the endogenous messenger or other drugs
antigen
a specific molecule that stimulates an immune response
bioavailability
the degree to which a drug or other substance becomes available to the target tissue after administration
blood-brain barrier
a barrier that prevents many substances from entering the cerebrospinal fluid from the blood; formed by glial cells that envelope the capillaries in the central nervous system, presenting a barrier to many water-soluble compounds through they are permeabl
ceiling effect
a point at which no clinical response occurs with increased dosage
clearance
the rate at which a drug is eliminated from a specific volume of blood per unit of time
contraindication
a disease, condition, or symptom for which a drug will not be beneficial and may do harm
dependence
a state in which a person's body has adapted physiologically and psychologically to a drug and cannot function without it
distribution
the process by which a drug moves from the blood into other body fluids and tissues and ultimately to its sites of action
dose
the quantity of a drug administered at one time
duration of action
the length of time a drug gives the desired response or is at the therapeutic level
elimination
removal of a drug or its metabolites from the body by excretion
first-order
depending directly on the concentration of the drug; elimination of most drugs is a first-order process in which a constant fraction of the drug is eliminated per unit of time
first-pass effect
the extent to which a drug is metabolized by the liver before reaching systemic circulation
half-life
the time necessary for the body to eliminate half of the drug in the body at any time; written as T1/2
homeostasis
stability of the organism
idiosyncratic reaction
an unusual or unexpected response to a drug that is unrelated to the dose given
indication
a disease, symptom, or condition for which a drug is known to be of benefit
induction
the process whereby a drug increases the concentration of certain enzymes that affect the pharmacologic response to another drug
inhibition
the process whereby a drug blocks enzyme activity and impairs the metabolism of another drug
interaction
a change in the action of a drug caused by another drug, a food, or another substance such as alcohol or nicotine
lipid
a fatty molecule, an important constituent of cell membranes
local effect
an action of a drug that is confined to a specific part of the body
loading dose
amount of a drug that will bring the blood concentration rapidly to a therapeutic level
maintenance dose
amount of a drug administered at regular intervals to keep the blood concentration at a therapeutic level
metabolic pathway
the sequence of chemical steps that convert a drug into a metabolite
metabolism
a substance into which a drug is chemically converted in the body
metabolite
a substance into which a drug is chemically converted in the body
peak
the top or upper limit of a drug's concentration in the blood
pharmacokinetic modeling
a method of describing the process of absorption, distribution, metabolism, and elimination of a drug within the body mathematically
pharmacokinetics
the activity of a drug within the body over a period of time; includes absorption, distribution, metabolism, and elimination
prophylaxis
effect of a drug in preventing infection or disease
pruritus
itching sensation
receptor
a protein molecule on the surface of or within a cell that recognizes and binds with specific molecules, thereby producing some effect within the cell
side effect
a secondary response to a drug, other than the primary therapeutic effect for which the drug was intended
solubility
a drug's ability to dissolve in body fluids
specificity
the property of a receptor site that enables it to bind only with a specific chemical messenger; to bind with a specific cell type, the messenger must have a chemical structure that is complementary to the structure of that cell's receptors
systemic effect
an action of a drug that has a generalized, all-inclusive effect on the body
therapeutic effect
the desired action of a drug in the treatment of a particular disease state or symptom
therapeutic level
the amount of drug in a patient's blood at which beneficial effects occur
therapeutic range
the optimum dosage, providing the best chance for successful therapy; dosing below this range has little effect on the healing process, while overdosing can lead to toxicity and death
tolerance
a decrease in response to the effects of a drug as it continues to be administered
trough
the lowest level of a drug in the blood
urticaria
hives, itching sensation
volume of distribution
mathematical relationship between the blood concentration attained and the amount of drug administered
wheals
slightly elevated, red areas on the body surface
zero-order
not depending on the concentration of the drug in the body; elimination of alcohol in a zero-order process in which a constant quantity of the drug is removed per unit of time