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2022 Drug Deck > Barbs > Flashcards

Barbs Flashcards

1
Q

Barbiturates are

A

weak acids

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2
Q

Barbiturates come prepared as

A

alkaline solutions

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3
Q

barbiturates with substitutions at carbon #2 and#5 have

A

sedative, hypnotic, properties

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4
Q

phenyl group at carbon#5 =

A

phenobarbital, increased anticonvulsant effect i.e. phenobarbitals

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5
Q

methyl group imparts

A

convulsant activity, i.e. methohexital

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6
Q

Sulfuration of barbiturates =

A

more fat soluble, lipid soluble,

so: shorter duration, more rapid onset, increase potency

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7
Q

sulfar at carbon #2 of barbiturate =

A

thiobarbibutrate

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8
Q

Barbiturates: MOA

A

MOA: Decreases the rate at which GABA dissociates from its receptors.

Increases duration of GABA activated Cl- channel opening

Overall: enhances GABA activity

  • Decreases transmission in the sympathetic ganglia : direct acting HYPOTENSION
  • Decreases post synaptic membrane sensitivity to Ach -> some muscle relaxation [[not surgical depth!]]

Depresses RAS -> induces sleep

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9
Q

onset of barbiturates

A

“one arm to brain” so rapid

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10
Q

Redistribution of barbiturates:

A

rapid termination of effect is from redistribution

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11
Q

metabolism of oxybarbiturates:

A

hepatic only CYP450

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12
Q

metabolism of thiobarbiturates:

A

hepatic and some ‘extra hepatic’

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13
Q

action of barbiturates is terminated by

A

side chain OXIDATION at C#5 to carboxylic acid.

HYDROLYSIS
DESULFRATION

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14
Q

renal excretion of barbiturates

A

<1% excreted unchanged

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15
Q

enzyme induction / inhibition and barbiturates

A

does not alter metabolism BUT will increase dose requirements

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16
Q

more potent isomer of barbiturates

A

s (-) levo isomer

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17
Q

alkinazation of urine favors

A

barb excretion

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18
Q

e 1/2 t of methohexital and thiopental

A 
methohexital = 3.9 hours 
thiopental = 11.6 hours
19
Q

cerebral protective effects of barbs

A

cerebrovasoconstriction, reduces CBF, decreases ICP, and CMRO2

20
Q

EEG + barbs

A

isoelectric, potent enough to accomplish this

21
Q

methohexital excitatory movements:

A

myoclonus and hiccups

22
Q

Barbs + pain

A

these are anti-analgesic

23
Q

barbs + IOP

A

Decrease IOP

24
Q

CV effects of barbs

A

Decreases SNS outflow leads to decrease SVR, SBP subsequent increase in HR from peripheral activation of SNS

Myocardial depression: minimal

SIGNIFICANT myocardial depression and BP with: large doses or pre-existing hypovolemia

ONLY IV.

PO barbs = minimal CV effects.

25
Q

CNS Is not intact in

A

tiny babies, elderly.

26
Q

histamine release?

A

with rapid IV admin of barbs

27
Q

respiratory effects of barbs

A

dose dependent depression of medullary and pontine ventilatory centers

decreased ventilatory RESPONSE to hypoxia / hypercapnia

28
Q

Barbs + laryngeal/cough reflexes

A

depression of both is incomplete . If dose is not large enough, we can see a “stage 2” repose to a/w manipulation - increased risk of laryngospasm, bronchospasm etc.

29
Q

most potent enzyme inducer =

A

phenobarbitals

30
Q

hepatic enzyme induction with barbs may lead to

A

increased metabolism of oral anti-coagulants, phenytoin, TCAs, corticosteroids, vit k.

31
Q

barbs can lead to accelerated production of

A

heme

32
Q

patients treated with barbs for sz disorders

A

metabolize drugs about 2x as fast, especially evident in muscle relaxants.

33
Q

venous thrombosis

A

effect of barbs

34
Q

tolerance of barbs develops

A

rapidly, more rapidly than can be described by enzyme induction.

35
Q

allergies with barbs

A

rare: 1:30,000 but high mortality.

allergy most common in atopic patient, those with multiple allergies, prior TPL exposure.

36
Q

things that cant be mixed with barbs

A

opioids, catechols, NMBs, midazolam, LR,

pancuronium, vecuronium, atracurium, alfentanil, sufentanil, midazolam, LR***

37
Q

to reconstitute barb

A

must use sterile H2O or NSS

38
Q

Intra-arterial injection of barb

A

would cause intense vasoconstriction, pain, crystals may form, possible loss of limb

39
Q

to treat intra-arterial injection of barb

A

dilute with NSS
phenoxybenzamine - noncompetitive antagonist.

prevent thrombosis, brachial plexus block of stellate ganglion block.

papaverine 40-80 mg to vasodilator.

40
Q

drugs to avoid with porphyrias

A 
thiopental
thiamylal
methohexital
etomidate
keterolac
phenacetin
pentazocine
41
Q

methohexital is used

A

for ECT because we dont want an isoelectric EEG

42
Q

histamine release can cause

A

bronchoconstriction

43
Q

phenobarbital is excreted

A

unchanged in the urine, all others are metabolized by CYP450

44
Q

branched chain on the number 5 carbon atom usually has

A

greater hypnotic activity than the corresponding drug with a straight chain

2022 Drug Deck (12 decks)

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