Introduction to Pharmacology Flashcards
What is pharmacodynamics?
What a drug DOES TO THE BODY (biological effects and mechanism of action)
What is pharmacokinetics?
What the body DOES TO THE DRUG (absorption, distribution, metabolism, excretion of drugs and their metabolites)
What are drugs?
Any synthetic or natural substance used in the treatment, diagnosis or prevention of a disease
More broadly, inc. caffeine, alcohol, nicotine, illicit/recreational drugs
Describe selectivity of a drug
For a drug to be useful, it must usually act with some degree of selectivity; drugs act by binding to TARGET molecules and selectivity arises from: Chemical structure of drug
Target recognising LIGANDS of a precise type
Role of regulation proteins in drug action?
Most drugs act by binding to regulatory proteins, e.g: enzymes, carrier molecules (pumps and transporters), ion channels and receptors; important additional targets are DNA and RNA
What are receptors?
Protein macromolecules that MEDIATE the biological actions of hormones and neurotransmitters
Types of drugs?
Agonist - drug that binds to a receptor to produce a cellular response; possess both affinity and efficacy
Antagonist - drug that blocks the action of an agonist; possess affinity but lack efficacy
What do affinity and efficacy mean?
Affinity - “strength” of association between ligand and receptor
Efficacy - ability of an agonist to evoke a cellular response
Relationship between agonist conc. and receptor occupancy?
As conc. increases, receptor occupancy increases until all receptors are occupied and a plateau is reached; this is called saturation (every receptor is occupied)
Relationship between agonist conc. (or dose) and response?
Hyperbolic relationship
The conc. of agonist that elicits a half-maximal response is EC50; it is a linear plot and so cannot present wide ranges of data.
If plotted SEMI-LOGARITHMICALLY , a wide range can be presented. Here, relationship between conc./dose and response is sigmoidal (s-shaped) and EC50 means the same
What is potency?
How much of the substance elicits a cellular response
Describe the difference between A, B and C
A and B are full agonists
A is a more potent agonist than B but has equal efficacy
A and C are equipotent
C is a partial agonist with a lower efficacy than either A or B
What is competitive antagonism?
Binding of agonist and antagonist occur at the same (orthosteric) site and is thus competitive and mutually exclusive
What is non-competitive antaognism?
Agonist binds to orthosteric site and antagonist binds to separate allosteric site and thus is not competitive. Both may occupy the receptor simultaneously, but activation cannot occur when antagonist is bound
Difference between agonist alone, agonist + non-competitive antagonist, and agonist + competitive antagonist?
In the presence of competitive antagonist, graph shifts parallel to the right as increased agonist conc. is required; there is no depression of maximal response
Non-competitive antagonists depress the slope and the maximum of conc. response but do not cause a parallel rightward shift
