Drug Receptors Flashcards
What is a receptor?
A component on or within a cell that substances can bind to- they have 3D surfaces to allow drugs to bind to them
What affects cell function?
-changing membrane permeability
-enzymatically
-linkage with proteins that control enzyme and chemical processes in the cell
How does a drug change the permeability of a cell?
Some receptors on cells are linked to ion channels. Thus when a drug attaches to the receptor it changes the permeability via the ion channel
Example: when AcH binds to AcH receptors, muscles become more permeable to sodium
How do intracellular enzymatic components work?
When a drug binds to an extracellular receptor (on the outside of a cell) it can cause a change on the intracellular component (inside the cell) which can change the biochemical function of the cell
Example: insulin
Where are intracellular receptors located?
in the cell’s cytoplasm and/or nucleus
How do drugs bind to receptors?
Drugs are made to bind to specific cells due to a lock and key mechanism- the drug is the “key” and will only fit into certain “locks,” meaning receptors
-drugs can bind to a receptor completely, partially, or minimally
What is Affinity?
The attraction between a drug and a receptor
-high affinity: a drug will bind easily to receptor
-low affinity: needs a very high concentration of a drug for it to bing to a receptor
What is selectivity?
When drugs affect only one type of cell or tissue and produce a very specific physiological response
-the more sensitive a drug is, the less side effects will be seen
What is the dose response curve related to?
it is related to the number of receptors that a drug binds to
-at low doses of a drug, only a few receptors will be bound by that drug so the effect will be small
-at larger doses of a drug, all available receptors will be used and the effect will be maximal
Agonists vs Antagonists
Agonists: drugs that bind to a receptor and initiate a change in the cell’s function
-have affinity and efficacy (there is attraction and a change in function occurs)
Antagonists: a drug that binds to a receptor but does not change the cell’s function
-have affinity but not efficacy (there is attraction but no change in function occurs)
-prevents agonists from binding to receptors
What are partial agonists?
Agonists who occupy receptors but they do not evoke maximal responses- they do not completely activate the receptor that they bind to
-used in order to minimize potential side effects of specific drugs
What are mixed agonist-antagonists?
When some drugs will bind to and stimulate one receptor subtype, but will also bind to and block another one simultaneously
What can prolonged exposure to a certain drug result in?
- receptor desensitization: a decrease in the number of receptors actively available (a brief and transient process)
- down-regulation: the actual number of receptors diminishes over time (slow process)
**both linked to drug tolerance
Is it possible for drugs to exert their effects without any interaction with a receptor?
Yes. Some drugs are capable of this. Stomach antacids neutralize stomach acids via a chemical reaction rather than binding to a receptor
