Benzos

Question 1

Benzos MOA (all the same)

Answer 1

Potentiate binding of GABA to GABA-A receptor, facilitating the opening of Cl- channels. This in turn hyperpolarizes the cell, decreasing excitability.

Question 2

Benzos uses (all the same)

Answer 2

Anxiolysis

Sedation

Anterograde amnesia

Spinal level muscle relaxation

Anticonvulsant

Question 3

Benzos specific antagonist

Answer 3

Flumazenil

Question 4

Diazepam (Valium) kinetics

Answer 4

Highly PB, highly lipid sol., large Vd, easily crosses BBB/placenta. Rapid onset.

CYP450 metab., urine excretion. E1/2t 21-37 hours. Least potent benzo.

3 active metabolites- desmethyldiazepam most active, lasts 48-96 hours.

Painful injection.

Question 5

Diazepam SE

Answer 5

Decrease CBF, CMR02. Cerebral CO2 response intact, but curve is flattened. Non-isoelectric EEG. Neuroprotective.

Decrease SVR, BP, CO with induction dose.

Decrease RR and TV at induction dose or with opioids.

Depresses deglutition reflex.

Largely CV stable, does not attenuate SNS response to DVL.

Question 6

Diazepam CI/Cautions

Answer 6

Early pregnancy

Glaucoma

Hypersensitivity

Decrease dose in renal/liver impairment

Large doses can cause very large drops in BP

Older pts very sensitive

Rare paradoxical excitement

Question 7

Diazepam dosing

Answer 7

Premed- 0.2mg/kg IV or 10-15mg PO

Induction- 0.5-1mg/kg IV

Question 8

Midazolam (Versed) kinetics

Answer 8

90-98% PB, highly lipid soluble, rapidly crosses BBB/placenta. Rapid onset. Water soluble prep.

CYP450 metab., urine excretion. E1/2t 1-6hrs. Redose in 5 min increments.

1 active metabolite- hydroxy midazolam. 50% as potent.

Question 9

Midazolam SE

Answer 9

Decrease CBF, CMRO2. Cerebral CO2 response intact, but flattened. Neuroprotective, non-isoelectric EEG.

Decrease in SVR, BP at induction dose. CO remains unchanged. Largely CV stable.

Dose dependent resp. depression. Decrease in RR and TV with opioids.

Does not attenuate SNS response to DVL.

Question 10

Midazolam CI/Cautions

Answer 10

Older pts are very sensitive

Decrease dose in hepatic/renal impairment

Rare paradoxical excitement

Question 11

Midazolam dosing

Answer 11

Premed- 1-2.5mg IV (max 5mg) or 0.5mg/kg PO (max 20mg)

Induction- 0.1-0.2mg/kg over 60 seconds

Question 12

Lorazepam (Ativan) kinetics

Answer 12

80% PB, highly lipid soluble, large Vd. Rapid onset IV, 2 hours for PO.

CYP450 metab., 80% unchanged in urine. E1/2t 10-20 hours.

Most potent benzo, no active metabolites, painful injection. Does not alter NMB dose.

Question 13

Lorazepam SE

Answer 13

Decrease CBF, CMRO2. Neuroprotective. Non-isoelectric EEG. Cerebral CO2 response intact, but curve flattened.

Decrease in SVR, BP, CO.

Decrease in RR and TV with opioids.

Depresses deglutition reflex. Does not attenuate SNS response to DVL.

Question 14

Lorazepam CI/Cautions

Answer 14

Decrease dose in hepatic/renal impairment

Older pts very sensitive

Rare paradoxical excitement

Question 15

Lorazepam dosing

Answer 15

Premed- 1-4mg IV or 50mcg/kg PO

Question 16

Flumazenil drug class

Answer 16

Imidazobenzodiazepine derivative

Question 17

Flumazenil MOA

Answer 17

Competes with benzos for GABA-A binding. High affinity, highly specific.

Question 18

Flumazenil uses

Answer 18

Reversal of benzos

Differential diagnosis of coma

Question 19

Flumazenil kinetics

Answer 19

50% PB, Vd 0.5L/kg, 1-2 min onset, 2-10 min peak, DOA 30-60 min. Painful injection.

Hepatic metab., urine excretion. E1/2t 60 min (shorter than most benzos)

Question 20

Flumazenil SE

Answer 20

Dizziness, sweating, HA, N/V, vision changes

Agitation, depression, confusion

HR, BP unchanged.

Question 21

Flumazenil CI/Cautions

Answer 21

Hypersens.

Do not use in any seizure disorder!

Question 22

Flumazenil dosing

Answer 22

0.2mg IV, wait 2 minutes

Repeat 0.1mg IV, wait 1 minute, repeat to a max of 3mg