Pharmacodynamics Flashcards
Think of the diagram
What is the action of adrenaline in the bronchi smooth muscle cells?
Adrenaline binds to the G-protein coupled receptor on the smooth cells -> this causes a conformational change to the receptor -> this then activates the G-protein -> the alpha subunit of the G-protein dissociates, and binds ADE-NY-LYL CYCLASE -> this then produces cAMP -> this causes intracellular signalling -> signals to relax the smooth muscle
Think of adrenaline and what it does to the heart
Why is SALBUTAMOL better than adrenaline for ashma?
This is because Adrenaline targets alpha 1, beta 1 and beta 2 receptors. Instead Salbutamol has a higher affinity for beta 2 receptors, therefore it is more selective than Adrenaline and causes less symptoms.
Alpha 1 - involved in VASOCONSTRICTION
Beta 1 - increases HEART RATE
Beta 2 - found in BRONCHIODILATION
- It lasts longer (4-6 hours) than Adrenaline
Think of the name, how selective it is
What does drug selectivity mean?
Ability for drug to DISCRIMINATE between two drug targets
From molecular level to whole body level
How can we measure drug response?
- Molecular level - tag the drug with flourescent tag, and see where the drug is in the cell
- Cellular level - measure the levels of cAMP
- Organ level - measure the response of the organ (e.g. contraction)
- Whole body level - peak flow (heart rate/blood pressure)
Think of, how powerful is the drug
What is drug potency?
Why is it relevant in the study of drugs?
The CONCENTRATION or DOSE of the drug needed to produce a defined effect.
Important to compare efficacy of drugs
Think of the graph of how effective a drug is. Y axis and X axis
What does a potency graph show? And what does EC50 and ED50 stand for?
A potency graph shows the concentration of a drug that is required to get a response. We can use it to compare drugs efficacy. We have drug A and B. If drug A is closer to the left of the graph than B, it is more effective. We know that the numbers in the X axis are bigger the more you go to the right. When we calculate the EC50, which is the concentration level of the drug required to achieve 50% of a response and ED50 which is the dose, by finding the middle of the max response to the min response, we see that we require less amount of A to achieve response compared to B.
How can you tell a drug has a high affinity?
What are the factors that affect affinity?
The lower the concentration of the drug you need, the higher the affinity. (it means that it doesnt take much of the agonist for it to bind to the receptor) So the MORE POTENT the drug, the higher its AFFINITY.
Structure of the drug and the conformation of the target - factors that determine affinity
How does change in DNA change receptor affinity?
Small change in DNA can change the structure and shape of the protein.
This at times has little to no effect, or it can make the individual have INCREASED or DECREASED response to the drug.
What does drug efficacy mean?
The ability of a drug to cause a response. Maximum effect of a drug. It will have the highest point on the response graph
Difference with full agonist, partial agonist, and least agonist
Full agonist - has the highest efficacy
Partial agonist - less efficacy than the full agonist
Least agnosit - lowest efficacy
What is the difference between drug efficacy and potency?
Drug potency is the concentration of the drug required to produce a defined response.
Drug efficacy is the highest effect of a drug
