The dose-drug relationship Flashcards
1
Q
What are the concepts of receptor theory (3)
A
- Agonist - produce a biological response
- Antagonist - blocks biological response
- The size of the response to a drug is proportional to the number of drug-receptor interactions that occur
2
Q
What is the dose-response relationship (2)
A
- Greater dose = more receptor interactions
- Maximum response = all receptors occupued by drug
3
Q
What is drug efficacy and drug potency (3)
A
- Drug efficacy - is the maximal response a drug can produce. Expressed as Emax.
- Drug potency - the dose of a drug that is required to produce a biological response.
- Potency is usually expressed as the concentration of drug required to achieve half the maximum biological response and is termed ED50 → 50% of the effective dose.
4
Q
What is the importance of the therapeutic window or therapeutic index of different drugs (5)
A
- a measure of drug safety
- A higher therapeutic index is safer than a lower therapeutic index
- LD50 is the dose that kills 50% of animals receiving it (50% Lethal Dose)
- Drugs with a low ‘Therapeutic Index’ = constantly monitored to prevent drug poisoning
- Some drugs, such as those used to treat cancer, are known to be toxic; however, the benefits outweigh the risk.
5
Q
What is affinity
A
the tendency of the drug to bind to the receptor to form a Drug-Receptor Complex
6
Q
What is efficacy
A
the ability of the drug to trigger a pharmacological response after forming a Drug-Receptor Complex
7
Q
What is an antagonist (2)
A
- drug occupies receptor = no biological response
- competitive or non-competitive
8
Q
How do competitive antagonists work (3)
A
- compete with agonists for the same receptor
- agonist = response, antagonist = no response.
- makes agonists look less potent
9
Q
How do non-competitive antagonists work (2)
A
- permanently bind to the receptor (covalent bond) or block the binding site
- reduces maximum response (efficacy) that an agonist can produce
