Drugs and Receptors Flashcards
Pharmacokinetics:
What the biological system does to the drug.
Pharmacodynamics:
What the drug does to the biological system.
Affinity:
Tenacity or persistent ability with which the drug binds to the specific receptors on the cell membrane.
Intrinsic activity:
Inherent property of the drug to impart a cellular response.
- What happens when drug –> receptor.
Agonist:
Binds to and stimulates a receptor.
Antagonist:
Binds to but does not stimulate a receptor (no intrinsic activity).
Partial agonist:
Agents that are only partly as effective as agonists no matter the amount employed.
Inverse agonist:
Agents which stabilize the receptor in its inactive form.
Signal transduction:
The process by which a receptor binding initiates a cascade of biochemical events that lead to a physiological response.
Specificity:
Act through single receptor type/subtype.
Selectivity:
Exert single effect.
Gs:
Stimulates adenylate cyclase.
- Increase cAMP.
Gi:
Inhibits adenylate cyclase.
- Decrease cAMP.
Gq:
Activates phospholipase C.
- Increase IP3, DAG.
cAMP:
- Used as second messenger.
- Regulates activity of protein kinases (PKA).
- Inactivated by PDE.
cGMP:
- Generated by guanylyl cyclase.
- NO stimulates soluble GC.
- Natriuretic peptides, guanylins stimulate membrane-spanning GC (particulate).
- Regulates activity of PKG.
Ca2+:
- Second messenger.
- May involve PLC and PIP2.
- IP3, DAG.
Transcription-related receptors:
- Hydrophobic ligands
1. Ligands enter cell via passive diffusion.
2. Bind to receptors in cytoplasm.
3. Complex binds to specific DNA response elements.
4. DNA transcription altered to increase/decrease synthesis of proteins.
Desensitization:
Receptor downregulation.
- After sustained agonist activity.
Supersensitization:
Receptor upregulation.
- After sustained antagonist activity.
Tachyphylaxis:
Loss of response on repeated administration.
- Slower dissociate of the agonist from its receptor.
