Pharmacodynamics Flashcards
Where do drugs normally target? Where else can they target and in what disease?
Normally target proteins - can target DNA e.g. In tumour drugs
Which receptor type is a common drug target in humans?
GPCRs
How can molarity of two drugs be the same but molecular weight be different?
Because M is number of molecules, and molecules of Ach for example are smaller than molecules of insulin, so insulin would have a higher Mg/L than Ach at the same Molar concentration
1M of substance is how many molecules? Called ____________’s Constant
1 x 10^23
Avogadro’s Constant
Affinity + Efficacy = ___________
Potency
Concentration of drug around receptors is critical for drug action true or false
True
What is affinity? How is this denoted and what is the explanation of this?
Ability of drug to bind to a receptor
Denoted by Kd (or KD or Ka) - is the conc of drug at which 50% of receptors are occupied
What is efficacy? What two types are there?
Efficacy is the ability of a drug to ellicit a cellular response.
Intrinsic efficacy - is a property of agonists - ability to activate the receptor they bind to
Efficacy - is the ability of an agonist to cause a cellular response
When would drugs that elicit an equal cellular response not actually have the same efficacy?
If the cellular response is submaximal, then one drug could have higher efficacy as equal response here may not mean equal strength of the two drugs
Do antagonists have efficacy?
No - they only have affinity as they do not elicit a cellular response
What is EC50? How can this be the same in two drugs but affinity/efficacy be different?
Effective concentration of drug that gives 50% maximal response. Denotes potency. Potency is affinity+efficacy so a lower/higher affinity or efficacy can be counterbalanced by the other meaning two drugs could have the same potency but different affinity and efficacy.
What is the difference between dose and concentration?
Dose is what’s given to patient - unknown quantity at site of action
Concentration - is known amount of drug at site of action.
How can you measure drug-receptor binding activity?
By using a radio-labelled ligand
What is BMAX? What does it give you an indication of?
Concentration of drug at which there is maximal receptor binding - gives you an indication of receptor numbers.
How could less than 100% occupancy of receptors give 100% response? Give an example of a receptor where this occurs. What are the leftover receptors called?
Because some agonists e.g. At GPCRs will have amplification of response, so may get full response at lower receptor occupancy - higher sensitivity. E.g. 10% occupancy of mAChR gives 100% contraction. Leftover receptors are “spare receptors”
