Drug-receptor interaction for organ bath practical Flashcards
What is a drug?
A medicine or other substance which has a physiological effect when ingested or otherwise introduced to the body.
What is Pharmacology ?
The study of the actions of drugs on living systems. Includes physical and chemical properties, biochemical and physiological effects, mechanisms of action, therapeutic uses and adverse effects of drugs.
What is the WHO definition of a drug ?
Any substance or product that is used to be modify or explore physiological systems or pathological systems or pathological states for the benefit of the recipient.
What are some sources of drugs ?
Plants
Animals
Minerals
Microorganisms
Human
Synthetic drugs
Many drugs are now synthesized (made in a lab)
Many drugs are obtained from cell culture
Some are now produced by recombinant DNA technology.
How do drugs work?
Drug molecules must exert some chemical influence on cell constituents to produce a pharmacological response.
Drug molecules must get so close to these cellular molecules that the two interact chemically in such a way that the function of the cell is altered.
Therefore drug molecules must be bound to constituents of cells and tissues in order to produce an effect
What do drugs bind to ?
Drug targets. Examples include:
Receptors
Enzymes
Carrier molecules
Ion channels
What is agonism and antagonism?
Agonist - any ligand which when bound to a receptor produces an observable response
Antagonist - any ligand that itself may not produce any response but interferes with the response to an agonist.
How can u test a drugs potency ?
Drug potency refers to the amount of a drug needed to produce a certain effect.
This is normally measured as the concentration of agonist producing half the maximal response to the the same agonist. (EC50)
The lower the EC50 - the more potent the drug
How can u test a drugs efficacy?
Efficacy describes the way in which agonists vary in the response they produce even when they occupy the same number of receptors.
High efficacy agonists can produce their max response while occupying a low proportion of receptors.
Low efficacy agonists cannot produce the same max response even when they occupy the entire receptor population and thereby are known as partial agonists.
What are the different types of agonists?
Full Agonist - these drugs are capable of producing the max response within tissues
Partial Agonists - these drugs cannot produce the max response within the same tissues even at the highest concentrations
Inverse Agonist - Some receptors have elevated basal activity and are constituently active. Inverse agonists have the ability to bind to these and produce a response that is opposite to that of an agonist.
What are antagonists ?
These agents stop or oppose the effects of agonists.
Chemical antagonists - a drug combines with another to form an inactive product.
Physiological antagonists - two drugs are physiological antagonists of one another if they bind to two different receptors and produce opposite effects.
Pharmacological Antagonists - alter the interaction between agonist and its receptor.
Pharmacological Antagonists
Pharmacological antagonists bind to receptors in a similar fashion to agonists
Unlike agonists, they do not produce an independent response when bound to the receptor. They compete with agonists from binding, thereby reducing or blocking activation of receptors by the agonist.
Competitive Antagonists
Compete with the agonist for the same receptor
However if high concentrations of agonist are administered, the agonist molecules will push the antagonist off the receptor and max response can be achieved.
Increasing antagonist conc will displace agonists from the receptor which means the EC50 increases but the Emax is unaltered.
Non competitive Antagonists
The effects of these are irreversible
The antagonist binds so strongly to the receptor that even when high concentrations of the agonist cannot push the antagonist off the receptor.
Increasing antagonist conc removes more receptors and it is no longer possible to occupy sufficient receptors to achieve Emax.
