Basic Drug Pharmacology Flashcards
What are the four main kinds of regulatory proteins commonly involved as primary drug targets?
- Receptors
- Enzymes
- Carrier molecules
- Ion channels
What is a receptor?
A target molecule through which soluble physiological mediators produce their effect
What are the main receptor classes?
A. Ligand-gated ion channels e.g. cholinergic nicotinic receptors
B. G protein-coupled receptors e.g. alpha and beta adrenoreceptors
C. Enzyme-linked receptors e.g. insulin receptors
D. Intracellular receptors e.g. steroid receptors
What is an agonist?
A substance that interacts with a specific cellular constituent, the receptor, and elicits an observable biological response - it may be an endogenous or exogenous substance
What is meant by a partial agonist?
Acts on the same receptor as agonists but regardless of its dose cannot produce the same maximal biological response as a full agonist.
What is an inverse agonist “negative antagonist”?
Acts on the same receptor of the agonist yet produces an inverse effect
What is meant by a spare receptor?
Receptors which exist in excess of those required to produce a full effect.
What is meant by intrinsic activity?
A proportionality constant of the ability of the agonist to activate the receptor as compared to the maximally active compound in the series being studied
What is an antagonist?
Inhibits the effect of an agonist but has no biological activity of its own.
Can compete for the same receptor site or act on the allosteric site
What is a competitive antagonist?
- Binds to the same site as the agonist in a reversible manner
What is a noncompetitive antagonist?
Binds to the same site as agonist irreversibly.
What is an allosteric antagonist?
Antagonist and agonist bind to different site on same receptor
What is a physiological antagonist?
Two drugs have opposite effects through differing mechanisms
What is a heteroreceptor?
A receptor that regulates the synthesis and/or the release of chemical mediators other than its own ligand.
What is an auto receptor?
A macromolecule typically found in the nerve ending that regulates the synthesis and/or release of its own ligand
What is meant by receptor down-regulation?
A phenomenon whereby an agonist induces a decrease in the number of those receptors available for binding.
What is meant by receptor up-regulation?
A phenomenon whereby an agonist induces an increase in the number of receptors available for binding.
What is meant by affinity?
The ability of a drug to combine with a receptor;
It is proportional to the binding equilibrium constant KD;
A ligand of low affinity requires a higher conc to produce the same effect
What is meant by efficacy?
A measure of the biochemical or physiological effect following the binding of a drug to its target;
It is a measure of the maximum effect the drug can produce
What is meant by potency?
Refers to the dose of a drug required to produce a specific effect of given magnitude as compared to a standard reference;
Potency is dependant upon both affinity and efficacy
What is a ligand?
Substance, molecules or compounds which bind with receptors present in the body;
They produce various effects and interfere with the flow of ions through channels called ligand gated channels
Describe the action of agonists.
Drugs bind to receptors;
cause activation of receptors;
Have capacity to produce chain reactions in the receptors;
Which bring about the effects
State the two properties of agonists.
- Affinity for receptor
- Capability to produce chain reactions in the cells having capability of intrinsic activity or efficacy
What is meant by the actions of drugs?
The biochemical physiological mechanisms by which the chemical produces a response in living organisms
What is meant by the effect of a drug?
The observable consequence of a drug action.
