Pharmacodynamics 1

Question 1

Define: Pharmacokinetics

Answer 1

Study of how the body affects the concentration of drug at the active site as a function of time (absorption, distribution, metabolism, excretion) What the body does to the drug

Question 2

Define: Pharmacodynamics

Answer 2

Study of how target cells respond to the delivered concentration of drug. What the drug does to the body

Question 3

Receptors as drug targets are:

Answer 3

Signal transduction systems
specific to ligands
stereospecific
obey mass action principles

Question 4

Receptors as drug targets can:

Answer 4

determine dose and effect relationship
determine drug selectivity
mediate action of agonist and antagonists

Question 5

Receptors for lipid soluble drugs

Answer 5

Enzymes, transcription factors, structural proteins. These take more time to act, but effects persist for hours or days.

Question 6

Transmembrane receptor kinase action

Answer 6

extracellular hormone-binding domain and cytoplasmic enzyme domain, dimerization upon ligand binding = activation of tyrosine kinase activity, leading to downstream to regulated by down-regulation - removal from cell surface

Question 7

How does the glucocorticoid receptor work?

Answer 7

Steroid causes the displacement of heat shock protein 90 (hsp90) allowing the transcription activating domain to become active

Question 8

Cytokine receptors action

Answer 8

same as TRK, except no intrinsic kinase activity. Instead, signal transduced by associated JAK-STAT signalling

Question 9

Ligand-gated channels

Answer 9

Mimic endogenous ligand. Very rapid response - milliseconds

Question 10

Voltage-gated channels

Answer 10

Allosteric binding. Very rapid response

Question 11

G-protein coupled receptors

Answer 11

7 transmembrane or serpentine receptor. GTP-G protein complex acts on second messenger. Either adenylyl cyclase or phospholipase C

Question 12

What do antiacids and osmolarity agents have in common?

Answer 12

They don’t act on receptors, but directly on ionic milieu

Question 13

Rapid desensitization

Answer 13

decreased ability of receptors to respond to stimulation by the drug - often though g-protein phosphorylation

Question 14

Resensitization

Answer 14

recovery of receptor after agonist is removed

Question 15

Down regulation -

Answer 15

Removal and degradation of receptor upon repeated or persistent drug-receptor interaction, cannot resensitize

Question 16

Dissociation constant

Answer 16

Concentration at which 50% of receptors are occupied.