Pharmacodynamics Flashcards
Basic Definition of Pharmacology and toxicology:
A. Pharmacology refers to the study of substances that interact with living systems through chemical processes
B. Toxicology is viewed as a branch of pharmacology with deals with adverse effects
Two functions of a drug receptor:
- Recognition - the receptor binds a drug or endogenous ligand
- Transduction - transfer of information
Describe Recognition, Selectivity, and Specificity of drug receptors.
A. The ability of a drug to bind with a receptor depends on the “goodness of fit” of drug to the receptor. This requirement for the receptor to recognize and bind a drug provides the basis for selective action at one or a small number of receptor sub-types.
B. The hundreds of different receptors types and their unique tissue localization impart specificity of drug action; that is, the ability of a drug to exert a distinctive influence on the body.
C. Proteins, which include enzymes, transporters, ion channels, structural proteins, and regulatory proteins, represent the majority of drug receptors.
What is transduction by cell receptors?
The interaction of a drug with its receptor propagates a signal, i.e. it converts the “drug signal” into a tissue response.
What are four common drug receptor mechanisms?
- G protein coupled receptors (GPCRs)
- most common; regulate 2nd messengers like cAMP, IP3, ect.
- Modulate ligand-gated ion channels (both cationic & anionic)
- Intrinsic enzyme activity phosphorylates diverse effector proteins
- Regulation of gene transcription
Two potential attributes of receptor mediated processes that can lead to durg-drug interactions:
- organization into opposing systems
2. Many receptors utilize a pool of relatively few 2nd messengers
What is the general idea of the Occupancy Theory?
drug + receptor drug receptor complex –> effect
or
X + R RX, where the forward association constant is k1 and the reverse reaction dissociation constant is k2
Define Potency.
a comparative term used to describe the relative positions of several agonist dose-response curves
the curve to the left (lower dose to cause effects) is more potent, it does NOT mean it has a higher maximum effect
a drug capable of inducing a maximum response, it has full efficacy (α = 1) is called:
full agonist
a drug whose maximal response is only a fraction of the maximum that can be elicited, it has partial efficacy (1 > α > 0)
partial agonist
a drug which inhibits the action of an agonist is an:
antagonist
A “pure” antagonist is a drug that can bind to a receptor, i.e. it has affinity for the receptor, but induces no response, i.e. it has zero efficacy (α = 0).
In the presence of a competitive antagonist, the agonist dose-response curve shifts to the_________. The slope of the curve________.
right, does not change
In the presence of a noncompetitive antagonist the maximal response of an agonist is______, and the slope of the curve is________.
reduced, reduced
An Inverse agonist is a drug that preferentially binds to the _______ form shifting equilibrium to the ________ form. This results in an effect _______ of that produced by an agonist.
inactive, inactive, opposite
