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Ch 5 Pharmacodynamics

Terms in this set (25)

Define Pharmacodynamics
the study of the biochemical and physiologic effects of drugs on the function of living organisms and thier component parts (how it works in the body)
Define Dose-response
This relationship is graded, that is the response gets more intense with increasing doage.
Define Maximal efficacy
The biggest effect a drug can produce!
A potent drug is simply a drug that produces its effects at ___________ doses. As a rule potency is not_____________
low
important
Potency and efficacy are ____________________ qualities
independent
Define receptor
any functional macromolecule in a cell to which a drug binds to produce its effects.
Binding of drugs to their receptors is almost always ______________.
reversible
name the four families of receptors:
1. cell membrane-embedded enzymes
2. ligand-gated ion channels
3. G-protein-couples receptor systems
4. transcription factors
Define affinity
the tendency of a drug to bind to a particular receptor (one to one). Also refers to the strength of the attraction between a drug and its receptor.
Drugs with high affinity have a realatve __________
potency
Define intrinsic activity
refers to the ability of a drug to activate receptors
Drugs with high intrinsic activity have high __________ _____________
maximal efficacy
Define Agonist
are molecules that activate receptors
Define Drug half life
the time required for the amount of drugs in the body to decrease by 50%
Define therapeutic index
TI= LD50/ED50, range of the effectiveness of the medication and the toxicity of the medication
Define hepatic first pass
refers to the rapid hepatic inactivation of certain oral drugs
What are some of the physiological considerations when prescribing in children?
*higher rate of metabolism
*higher water concentration
*kg
Considerations in drug treatment of the elderly?
increased gastric pH
increased GI transit time
decreased blood flow
decreased skin hydration
increased keratinization of cells
decreased in lean body mass
increasd total body fat
decreased total body water
decreased albumin levels
decrease GFR
decreased secretion
decrease liver mass or volume
decreased liver blood flow diminished enzyme activity
Presystemic biotranformation of a drug often occurs with:
first pass hepatic effect in the liver
Define absorption
The movement of a drug from its site of administration into the blood. The rate of absorption determines how soon effects will begin. The amount of absorption helps determine how intense effects will be
Define antagonist
produce their effects by preventing receptor activation by endogenous regulatory molecules and drugs.
Define bioavailability
refers to the ability of a drug to reach the systemic circulation from its site of administration
define excretion
removal of the drug (and metabolites) out of the body. drugs and metabolites can exit the body in urine, bile, sweat, saliva, breast milk and expired air. The most important organ for drug excretion is the kidney
Define hepatotoxicity
the tendency of an agent, usually a drug or alcohol, to have a destructive effect on the liver.
Define steady-state
a basic physiologic concept implying that the various forces and processes of life are in a state of homeostasis. Living organism are in constant flux, working to balance the internal and external environments in an effort to avoid a deficiency or an excess that might cause illness. Steady state is a complete state of well-being involving total adaptation
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