Oral: Induction Agents

Question 1

Propofol: Drug Class

Answer 1

Non-Barbituate Induction agent / Sedative / Hypnotic

Question 2

Propofol: MOA

Answer 2

1: discourages dissociation of GABA from GABA-A receptor; increasing Cl- conduction, hyperpolarized cell, and decreases neuronal transmission.
2: Also inhibits glutamate at the NMDA receptor.

Question 3

Propofol: Pharmacokinetics

Answer 3

90% PB; highly lipid soluble
onset- rapid 30sec;
DOA- short < 15min (terminated by rapid redistribution);
E1/2- 1 hrs;
conjugated in liver by CYP450 & excreted in the urine;
extrahepatic metabolism;
active metabolite: 4-hydroxy-propofol (1/3 pot);

Question 4

Propofol: Side Effects

Answer 4

⬇ CBF, CMRO2, ICP; 
isoelectric EEG; 
severe drop in BP and SVR, 
dose dep ⬇RR, bronchodilation,
pain on injection

Question 5

Propofol: Contraindications

Answer 5

Soy, egg allergy; hypovolemia, use with caution in elderly or those w/ myocardial depression.

Question 6

Propofol: Dosing

Answer 6

Induction 1-2.5 mg/kg IV (reduce w/ increasing age &/or myocardial depression);
Sedation 25-100 mcg/kg/min;
maintenance 100-300 mcg/kg/min;
antiemetic 10-20 mg IV

Question 7

Ketamine: Drug Class

Answer 7

Non-Barbituate Induction agent / Sedative / Hypnotic

Question 8

Ketamine: MOA

Answer 8

Blocks NMDA receptor (decreases ion influx, decreases neurotransmission),
opioid receptor agonist (analgesia),
muscarinic antagonist

Question 9

Ketamine: Pharmacokinetics

Answer 9

12% (poor) PB; 
highly lipid soluble; 
onset- rapid 30sec; 
DOA= short < 15min; 
E1/2- 2-3 hrs; 
metabolized by CYP450 to norketamine, then hydrolized and conjugated to be water soluble and excreted in urine.  Some eliminated unchanged in urine and feces. 

norketamine (active metabolite)~30%

Question 10

Ketamine: Side Effects

Answer 10

⬆CBF, CMRO2, ICP & IOP, 
emergence delerium, 
⬆SNS response b/c it inhibits NE uptake; 
direct myocardial depressant, ⬆ HR, SVR, BP; bronchodilation; 
⬆ saliva, 
hallucinations, 
myoclonus, 
potentiates NMB; 
causes dissociative anesthesia.

Question 11

Ketamine: Contraindications

Answer 11

Psych disorders, head injury, eye injury or surgery, CAD, HTN/PHTN, pheochromocytoma

Question 12

Ketamine: Dosing

Answer 12

Induction 0.5-2 mg/kg IV;
Sedation/Analgesia 0.2-0.5 mg/kg;
maintenance 1-2 mg/kg/hr IV, 5-10 mg/kg IM/PR?

Question 13

Etomidate: Drug Class

Answer 13

Non-Barbituate Induction agent / Sedative / Hypnotic

Question 14

Etomidate: MOA

Answer 14

Mimics GABA at GABA-A receptors and increases affinity for GABA to GABA-A receptor. Increases Cl- conduction, hyperpolarizes cell, and decreases neuronal transmission.

Question 15

Etomidate: Pharmacokinetics

Answer 15

75% PB; 
lipid soluble; 
onset- rapid 30-60sec; 
DOA- short < 15 min; 
E1/2= 3 hrs; 
liver hydrolysis by CYP450 and metabolized by plasma esterases and excreted in urine and bile.

Question 16

Etomidate: Side Effects

Answer 16

decrease CBF, CMRO2, ICP,  
can increase EEG- causing seizures; 
NO change in BP, HR, SVR, CO- very cardiac stable; 
Potentiates NMB;
 30-40% N/V; 
myoclonus; 
hiccups; 
adrenocorticoid suppression - may need cortisol replacement; pain on injection

Question 17

Etomidate: Contraindications

Answer 17

seizures, porphyria, Addison’s disease/adrenal insufficiency

Question 18

Etomidate: Dosing

Answer 18

induction- 0.2-0.6 mg/kg;
sedation- 5-8 mcg/kg/min;
maintenance- 10 mcg/kg/min

Question 19

Dexmedetomidine (Precedex): Drug Class

Answer 19

Non-Barbituate Induction agent / Sedative / Hypnotic

Question 20

Dexmedetomidine (Precedex): MOA

Answer 20

Alpha 2 agonist;

⬇ NT release (presynaptically) causing sedation, anxiolysis, analgesia;

Question 21

Dexmedetomidine (Precedex): Pharmacokinetics

Answer 21

90% PB; 
water soluble; 
Onset- Rapid < 5 min
DOA- < 2hr
E1/2- 3 hrs;
conjugated in liver by CYP450, excreted in urine and bile;

Question 22

Dexmedetomidine (Precedex): Side Effects

Answer 22

⬇ CBF but no change in CMRO2 & ICP; 
⬇ BP, HR, SVR;  
minimal change to RR and small ⬇ in TV; 
potentiates the effects of opioids and anesthetics; 
⬇thermoregulation;

Question 23

Dexmedetomidine (Precedex): Contraindications

Answer 23

Afib, HB, severe bradycardia, pts that cannot tolerate lower BP or HR

Question 24

Dexmedetomidine (Precedex): Dosing

Answer 24

1 mcg/kg over 15 min bolus, then 0.2- 1 mcg/kg/hr