20.6 Pharm: Transmitters and receptors

Question 1

How does phenytoin work as an epilepsy drug?

Why is this particularly good?

Answer 1

Limits excitatory (glutamate) nerve activation- inhibits Na channels

The effect is enhanced during high frequency firing

Question 2

How do benzos work?

Answer 2

Bind to GABA receptor and enhance (inhibitory) activity

Question 3

Do we still use barbituates as anxiolytics/hypnotics? Why?

Answer 3

Obsolete, exceedingly toxic and highly addictive

Question 4

Which receptor do benzos interact with?

What kind of modulator is it?

Answer 4

GABA A (ligand gated ion channels)

Allosteric modulator- increased affinity (increased frequency of Cl- opening)

Question 5

What are some advantages of allosteric modulation? (3)

Answer 5

1. Ceiling of effect
2. Positive modulation of ENDOgenous agonist
3. Receptor subtype selectivity

Question 6

What is the difference between potency and efficacy?

Answer 6

Potency: position of dose-effect along axis

Efficacy: ability to do the right thing (pharmacological- strength of R’ activation)

Question 7

How do barbituates produce their effects?

Answer 7

Increase the duration of the chloride ion channel opening at GABA A R’

Question 8

How do the pharmacodynamics of benzos vs. barbituates compare?

Answer 8

Benzos: increased potency of GABA

Barbituates: increased efficacy of GABA