Transmitters and Receptors

Question 1

In what ways can drugs interfere with neurotransmission?

Answer 1

synthesis, storage, release, reuptake, metabolism and receptor

Question 2

What is the action of phenytoin?

Answer 2

limits excitatory nerve activation by blocking the sodium channel while it is open - the neuron must have high frequent firing for the drug to bind - use in epilepsy

Question 3

What is the action of benzodiazepines?

Answer 3

binds the GABA A receptor at an allosteric site to increase the frequency of opening of the channel - used in epilepsy, anxiety, sedation, sleep disorders

Question 4

What is the action of barbiturates?

Answer 4

binds GABA receptor and prolongs opening of the channel

Question 5

Why are benzodiazepines used now instead of barbiturates?

Answer 5

wider therapeutic index, less respiratory and cardiovascular depression, less dependence, considered safe in overdose

Question 6

What are the advantages of allosteric modulators?

Answer 6

there is a ceiling effect (overdose is not lethal), modulate endogenous agonist rather than adding an exogenous agonist, great receptor subtype selectivity possible

Question 7

What is potency?

Answer 7

the relative position of the dose effect curve along the dose effect axis - has little clinical significance - a more potent of two drugs is not clinically superior

Question 8

What is efficacy?

Answer 8

the ability of a drug to do the right thing - pharmacologically the strength of receptor activation - clinically the strength of the beneficial effect