Chapter 2 Flashcards
Process that occurs from the time a drug enters the body to the time it enters the bloodstream to be circulated
Absorption
Drug that produces effects similar to those produced by naturally occurring hormones, neurotransmitters, and other substances
Agonist
Drug that inhibits cell function by occupying receptor sites
Antagonist
Substance that relieves, prevents, or counteracts the effect of a poison
Antidote
Portion of a drug dose that reaches the systemic circulation and is available to act on body cells
Bioavailability
When drugs are altered from their original form into a new form by the body; also referred to as metabolism
Biotransformation
Transport of drug molecules w/in the body; after a drug is injected or absorbed into the bloodstream, it is carried by the blood and tissue fluids to its sites of action, metabolism, and excretion
Distribution
Drugs or metabolites that are excreted in bile, reabsorbed from the small intestine, returned to the liver, metabolized, and eventually excreted in urine
Enterohepatic Recirculation
Production of larger amounts of drug-metabolizing enzymes by liver cells; process accelerates drug metabolism because larger amounts of the enzymes (and more binding sites) allow larger amounts of a drug to be metabolized during a given time
Enzyme Induction
Process in which a molecule binds to enzymes and inhibits their activity
Enzyme Inhibition
Elimination of a drug from the body; effective excretion requires adequate functioning of the circulatory system and of the organs of excretion (kidneys, bowel, lungs, and skin)
Excretion
Initial metabolism of some oral drugs as the are carried from the intestine to the liver by the portal circulatory system prior to reaching the systemic circulation for distribution to site of action
First-pass Effect
Immune-medicated reaction to a drug
Hypersensitivity
Dose larger than the regular prescribed daily dosage of a medication; used to attain a therapeutic blood level
Loading Dose
Quantity of drug that is needed to keep blood levels and/or tissue levels at a steady state or constant level
Maintenance Dose
Toxics or damaging effect of a substance on the kidney; potentially serious because renal damage interferes with drug excretion, causing drug accumulation and increased adverse effects
Nephrotoxicity
Reactions between living systems and drugs; drug actions on target cells and the resulting alterations in cellular biochemical reactions and functions
Pharmacodynamics
Drug movement through the body to reach sites of action, metabolism, and excretion
Pharmacokinetics
The occurrence of 2 or more clearly different forms (phenotypes) in a species important in drug therapy because it explains the functionality different response to drugs in a general pt population or a specific individual
Polymorphism
Initially inactive drugs that exert no pharmacologic effects until they are metabolized
Prodrugs
Laboratory measurement of the amount of a drug in the blood until a particular time
Serum Drug level
Time required for the serum concentration of a drug to decrease by 50%; also called elimination
Serum Half-Life
Chemicals that alter basic processes in body cells
- can stimulate or inhibit normal cellular functions; cannot change type of function that occurs normally
- must reach adequate concentrations in the blood and other tissue fluids surrounding the cells
Drugs
3 main pathways of drug movement across cell membranes
1) direct penetration of the membrane by lipid-soluble drugs (able to dissolve in the lipid layer of the cell membrane-systemic drugs)
2) passage through protein channels that go all the way through the cell membrane (only a few are able to use this pathway, molecules are too large)
3) involves carrier proteins that transport molecules from one side of the cell membrane to the other
Pathways
Most common mechanism, involves movement of a drug from an area of higher concentration to one of lower concentration. This promotes movement of the drug into the bloodstream. Continues until a state of equilibrium is reached between the amount of drug in the tissues and the amount in the blood
Passive diffusion
Drug molecules combine with a carrier substance, such as enzyme or protein. Similar to the passive diffusion process
Facilitated diffusion
Drug molecules are moved from an area of lower concentration to one of higher concentration. This process requires a carrier substance and the release of cellular energy
Active transport
Onset of drug action is largely determined by the rate of absorption; intensity is determined by the extent of absorption
*numerous factors affect the rate and extent of absorption, including dosage form, route of administration, blood flow, to the site of administration, GI function, the presence of food or other drugs, and other variables
Absorption
The frequency, size, and number of doses; it is a major determinant of drug action and responses, both therapeutic and adverse.
- if amount is too small or administered infrequently, no pharmacological action occurs because the drug does not reach an adequate concentration at target cells
- if amount is too large or administered too often, toxicity (poisoning) may occur. Overdosage may occur with a single large dose or with chronic ingestion of smaller doses
Dosage
Affect drug actions and pt responses largely by influencing absorption and distribution.
- IV=most effective (directly to bloodstream)
- IM=few minutes in some drugs (muscles have large blood supply)
- oral=slower than parenteral routes
- topical=according to drug formulation, applied to skin or mucous membranes, and other factors
Route of administration
the FDA requires drug manufacturers to place a warning on drug groups or individual drugs that may cause serious or life threatening adverse effects, formatted with a box or border around the text on the label of a prescription drug or in the literature describing it
BLACK BOX WARNING (BBW)
Activated charcoal
Universal antidote
