Session 8 - Drugs + Receptors/Pharmacokinetics Flashcards
1 mole of any substance contains how many particles?
6x10^23
What is the relationship between molecular weight, grams per litre and molarity?
Molecular weight x Molarity = Grams per litre
What is affinity?
The likelihood of a ligand binding to its target
What is efficacy?
Likelihood of activation of the receptor
In terms of affinity and efficacy which do agonists and antagonists have?
Agonists have both affinity and efficacy
Antagonists have just affinity
What is Bmax?
Maximum binding capacity
What is Kd?
The dissociation of constant, it is a measure of affinity.
It is the concentration of drug needed for 50% occupancy
What does a low Kd value mean?
High affinity
How do dose response curves differ from concentration response curves?
Conc response curves used in measuring a response at particular cells/tissues
Dose response curves used in measuring a response in the whole animal
What is Emax?
The maximum possible response
What is EC50?
Concentration giving 50% of the max response
Why does salbutamol have small side effects?
Selective EFFICACY + route of administration limit Beta-1 activation
Why does salmeterol have limited side effects?
Very high selective AFFINITY for beta-2 receptors
Describe the concept of spare receptors?
In some cases less than 100% occupancy can still result in a 100% response, so there are are spare receptors
How are spare receptors useful?
It allows for increased sensitivity, allowing for responses at lower concentrations of agonists
What are partial agonists?
Partial agonists cannot produce a maximum response even at at 100% occupancy
Name the partial agonist involved in morphine addiction
And how does it work?
Buprenorphine
It has a higher affinity for the opioid receptors than morphine, but a lower efficacy. This means it out-competes morphine for the receptors and provides sufficient pain relief but causes less respiratory depression than morphine
Name the three types of antagonists
Reversible competitive
Irreversible competitive
Non-competitive
List some of the main drug targets
- Enzymes (47%)
- GPCR’s (30%)
- Ion channels (7%)
- Transporters (4%)
- Nuclear hormone receptors (4%)
