Barbiturates Flashcards Preview

Cology 2 Exam 1 > Barbiturates > Flashcards

Flashcards in Barbiturates Deck (21):
1

What are the CNS effects of Barbiturates? What are they actually used for?

Anxiolytic, anticonvulsants, sedation/hypnosis

Too much sedation to use for the first two

VERY LOW therapeutic index and rapid tolerance to sedation, so rarely used for that too

2

How to treat barbiturate toxicity?

Supportive treatment only
Stomach pump
Hemodialysis
NO antidote

3

How do barbiturates effects on sleep compare to BDZ's?

Same
Decrease sleep latency, increase sleep time
Increase stage 2
Decrease stages 1, 3, and 4 and REM sleep

4

How are barbiturates as anesthetics?

They are very short acting

5

How do barbiturates work?

They increase affinity of both BDZ and GABA binding site
Prolong channel open time
Can also directly open GABA channels themselves at high doses!

Also decrease glutamate AMPA receptor binding, inhibit voltage-gated calcium channels (dangerous), and fluidize membranes (dangerous)

6

What subunits are required for barbiturates to work?

Alpha and beta of any type

7

At what doses does bicuculline work? Why?

Bicuculline can only work at low barbiturate doses because at high enough doses barbiturates can open the channel themselves

8

At what doses can picrotoxin work? Why?

Picrotoxin can work at high barbiturate doses because it blocks the ion channel, so no matter if GABA or barb opens the channel, nothing can go through.

9

Why is therapeutic use of barbs limited?

They can cause decreased respiration
Decreased BP
and an allergic reaction in asthmatic

10

Describe the pharmacokinetics of barbiturates

High lipophilicity, short duration of actions but they stick around. They can build up over time if given daily, and many have a half life over 24 hours.

Most orally absorbed.

Hepatically metabolized/conjugation followed by renal excretion

11

How do barbiturates affect liver metabolism?

Initially: Inhibit CYP2 and CYP3 activity to increase drug concentrations
Chronic: Induce CYP2 and CYP3 to decrease drug concentrations

Drugs included: Sedative/hypnotics, anesthetics, opiates, steroids, digitoxin, oral anticoags, B-antagonists, quinidine, phenytoin, ethanol, haloperidol, vitamins D and K, bile salts, and cholesterol

12

Which barbiturate is used as an anticonvulsant? How does it work?

Phenobarbital

Partial GABA agonist, less calcium inhibition
Less sedative side effects (rapid tolerance to it anyway)

13

Which barbiturates are used as anesthetics?

Thiopental
Methohexital
Thiamylal

14

Which barbiturates are rarely used?

Amobarbital
Aprobarbital
Butabarbital
Pentobarbital
Secobarbital
Thalbutal

15

Pharmacokinetic tolerance to barbiturates is due to what

Induction of CYP3A4, reaches peak after 3 days

16

Pharmacodynamic tolerance peak occurs when?

No time limit

17

Tolerance to barbiturate effects mostly occurs to....

Sedation
Less to ancitonvulsant

18

How does physical dependence with barbiturates compare to BDZ?

Occurs much more rapidly and severely

19

Physical dependence on barbiturates occurs due to...

Decreased GABA receptor function
Increased membrane rigidity
Increased glutamate receptors

20

What are side effects of chronic use of barbiturates?

Induces metabolism of many drugs
Increases fat and protein accumulation in the liver

21

What is the abuse liability of barbiturates?

Increases mesolimbic dopamine similar to alcohol