Chapter 5 - Pharmacodynamics Flashcards
Pharmacodynamics
the study of what drugs do to the body and how they do it.
Dose-response relationship
the relationship between the size of an administered dose and the intensity of the response produced
determines the minimum amount of drug needed to elicit a response, the maximum response a drug can elicit, and how much to increase the dosage to produce the desired increase in response.
Dose-response curves reveal two characteristic properties of drugs:
maximal efficacy and relative potency.
Maximal efficacy
the largest effect that a drug can produce.
Maximal efficacy is indicated by the ____ of the dose-response curve
height
What are the four primary families of receptors?
- cell membrane–embedded enzymes
- ligand-gated ion channels,
- G protein–coupled receptor systems,
- transcription factors
Where is the ligand- binding domain located in Cell membrane- embedded enzymes?
cell surface, and the enzyme’s catalytic site is inside
Cell Membrane–Embedded Enzymes
Binding of an endogenous regulatory molecule or agonist drug activates the enzyme, thereby increasing its catalytic activity ex insulin
Ligand-Gated Ion Channels
The function of these receptors is to regulate flow of ions into and out of cells. GABA AND ACETYLCHOLINE
Like membrane-embedded enzymes, ligand-gated ion channels span the cell membrane
G Protein–Coupled Receptor Systems
G protein–coupled receptor systems have three components: the receptor itself, G protein (so named because it binds guanosine triphosphate [GTP]), and an effector (typically an ion channel or an enzyme).
Transcription factors
differ from other receptors in two ways: (1) transcription factors are found within the cell rather than on the surface, and (2) responses to activation of these receptors are delayed
Ex - Steriods and thyroid hormones
What is the function of transcription factors?
regulate protein synthesis
affinity
refers to the strength of the attraction between a drug and its receptor
** Drugs with high affinity are strongly attracted to their receptors **
intrinsic activity
the ability of a drug to activate a receptor upon binding
The intrinsic activity of a drug is reflected in its ________
maximal efficacy
an antagonist is a drug with affinity for a receptor but with no ______
intrinsic activity
A partial agonist is an agonist that has only moderate
intrinsic activity ex- Pentazocine(Talwin) a narcotic
The therapeutic index is defined as ______
the ratio of a drug’s LD50 to its ED50.
The therapeutic index is a measure of
a drug’s safety.
The ED50 is defined as ____
the dose that is required to produce a defined therapeutic response in 50% of the population
What are some examples of drugs that do not act of receptors?
antacids, antiseptics, saline laxatives, and chelating agents.
Partial agonists are interesting in that they can act as
antagonists as well as agonists
Competitive antagonists bind _____ to receptors
reversibily
Noncompetitive antagonists bind _______ to receptors.
irreversibily
