PHARMACOLOGY-IV anesthetics Flashcards
Propofol MOA= Onset= Duration= pKa=
MOA= GABA-A agonist increasing Cl- conductance and neuron hyperpolarization. Prevents AP
Onset= 30-60 seconds
Duration= 5-10 minutes
pKa=11
Propofol Clearance= Active metabolite= Induction dose= Maintenance dose=
Clearance= liver + extra hepatic metabolism (lungs)
Active metabolite= none
Induction dose= 1.5-2.5 mg/kg IV
Maintenance dose= 25-200 ,cg/kg/min
Propofol
Respiratory effects=
CV effects=
CNS effects=
Respiratory effects= decreased respiratory drive
CV effects= decreased BP, SVR, preload, and contractility
CNS effects= Decreased ICP and IOP, NO analgesia +/- SZ activity
What is the chemical name and class for propofol
Name = 2,6- diisopropylphenol Class = Isopropylphenol
How do GABA-A receptors react when stimulated
Cl- conductance is increased, hyperpolarizing the neuron. This reduces the resting membrane potential making an action potential less likely
What causes the respiratory depressant effect when propofol is administered
A shift in the CO2 response curve down and to the right means there is less sensitivity for CO2 to drive respirations
What specific respiratory drive does propofol inhibit
hypoxic ventilatory drive
How are cerebral blood flow and oxygen consumption affected by propofol
Both are decreased
What miscellaneous properties does propofol have
Antioxidant properties = free radical scavenger
Altered urine color d/t phenol excretion (green) or increased uric acid excretion (cloudy)
What are 2 preservatives that may be added to propofol
- Disodium edetate (Diprivan)
2. sodium metabisulfate (generic)
Can patients with allergies to soy, peanuts, and egg receive propofol
Yes
What part of an egg is used in propofol production.
How does this relate to people with egg allergies
Egg lecithin found in propofol is derived from the yolk
People are usually allergic to the albumin in the egg white
What are clinical presentations of propofol infusion syndrome
Metabolic acidosis (base deficit > 10 mmol) Rhabdomyolysis Renal failure Hyperlipidemia Enlarge fatty liver Lipemia
What is the treatment for propofol infusion syndrome
D/C propofol Initiate cardiac pacing Start PDE inhibitors ECMO Glucagon CRRT
What is the discard time for infusion and syringes of propofol
Infusion = 12 hours Syringes = 6 hours
How do the additives in propofol cause possible complications
Metabisulfite = bronchospasm in asthmatic patients
Benzyl alcohol = should be avoided in infants
Other than sedative properties, what properties does propofol contain
Antipruritic
Antiemetic
Antioxidant
D/t the long-chain triglycerides in propofol what can be impaired?
Why is this significant?
Oxidative phosphorylation
Fatty acid metabolism
Significance = cells are starved of O2, especially in cardiac and skeletal muscle
What are risk factors for propofol infusion syndrome (6)
- Propofol dose >4 mg/kg/hr
- Infusion duration > 48 hrs
- Sepsis (inadequate O2 delivery)
- Continuous catecholamine infusions
- High-dose steroids
- Significant cerebral injury
Why is contamination concerning with propofol infusion or syringes
It supports bacterial and fungal growth
How is propofol injection pain minimized (3)
Inject into larger more proximal vein
Giving opioid before propofol
Giving lidocaine before propofol
What dose of propofol can be an effective antipruritic
10 mg IV
What dose of propofol can be an effective antiemetic
10 - 20 mg IV
Fospropofol MOA= Onset= Duration= pKa=
MOA= GABA-A agonist
Onset= 5 - 13 minutes
Duration= 15 - 45 minutes
pKa=
Fospropofol Clearance= Active metabolite= Induction dose= Repeat dose=
Clearance= liver + extrahepatic metabolism
Active metabolite= propofol
Induction dose= 6.5 mg/kg IV
Repeat dose= Max 1.6 mg/kg q4min
Fospropofol Respiratory effects= CV effects= CNS effects= Other=
Respiratory effects= similar to propofol
CV effects= similar to propofol
CNS effects= similar to propofol
Other= genital and anal burning
Class of fospropofol
isopropylphenol
How is the formulation for fospropofol different from propofol
It’s an aqueous solution which prevents burning on injection and doesn’t support microbial growth
What is the MOA of fospropofol
It’s metabolized to propofol by the enzyme alkaline phosphatase which prolongs onset. It binds to GABA-A increasing Cl- conductance
Which receptor does ketamine antagonize
NMDA
Ketamine MOA= primary and secondary Onset= (IV, IM) Duration= pKa=
MOA= -Primary = NMDA antagonist -Secondary = binds to secondary receptors i.e. opioid, MAO, serotonin, NE, muscarinic, Na+ channel Onset -IV= 30-60 sec -IM= 2 - 4 min Duration= 10-20 minutes pKa= 7.5
Ketamine Clearance= Active metabolite= Induction dose= (IV, IM) Opioid sparing dose=
Clearance= liver Active metabolite= Norketamine Induction dose= -IV = 1-2 mg/kg -IM = 4-8 mg/kg -PO=10 mg/kg Opioid sparing dose= 0.1-0.5 mg/kg
Ketamine Respiratory effects= CV effects= CNS effects= Other=
Respiratory effects= maintains respiratory drive, increased oral secretions
CV effects= Increased SNS tone, SVR, HR, CO
CNS effects= Increased ICP, IOP, nystagmus, analgesia. Emergence delirium, lowers SZ threshold.
Other= Avoid with acute intermittent porphyria
Chemical name and class of ketamine
Name = 1-(o-Cholophenyl)-2(methylamino) cyclohexanone hydrochloride
Class = Arylcyclohexylamine; phencyclidine derivative
What is the formulation or ketamine
Aqueous solution available as 1%, 5%, and 10% solutions
Racemic mixture
Ketamine MOA
NMDA receptor antagonist. Antagonizes glutamate
Dissociates the thalamus (sensory) from the limbic system (awareness)
Describe the clearance of ketamine
Liver (P450 enzymes)
-Chronic ketamine use induces the enzymes that metabolize it
How does chronic ketamine use affect the enzymes that metabolize it.
Why is this significant?
It’s an enzyme inducer
This causes rapid escalation in tolerance
What is the metabolite for ketamine?
Describe the potency of the metabolite
Active metabolite = norketamine
potency = 1/3 - 1/5 the potency of ketamine
How is ketamine excreted
Renal
How does ketamine affect the myocardium if SNS isn’t intact
It is a myocardial depressant
If catecholamines are depleted or SNS isn’t intact, then myocardial depression will be prominent. Can cause severe bradycardia d/t muscarinic action
What are respiratory effects of ketamine
- Bronchodilation
- Airway reflexes remain intact
- Respiratory drive remains intact
How does ketamine affect the CO2 response curve
Does not significantly shift CO2 response curve
What are CNS effects of ketamine
- increased CMRO2
- increased cerebral BF
- increased ICP
- increased IOP
- increased EEG activity
- Emergence delirium
How does emergence delirium present with ketamine use?
What is helpful
Nightmares and hallucinations
Benzodiazepines are effective in preventing emergence delirium
How does ketamine affect pain
- Good analgesia with opioid-sparing effects
- Relieve somatic pain > visceral pain
- Blocks central sensitization and effects in the dorsal horn of the SC
- prevents hyperalgesia following remifentanil infusion
What conditions should ketamine use be avoided in
CAD
Acute intermittent porphyria
What is an off-label use for ketamine
sub-hypnotic doses can treat MDD resistant to treatment
What is the plasma protein binding for ketamine?
How does this relate to other IV anesthetics?
12%
MUCH lower
Etomidate MOA= Onset= Duration= pKa=
MOA= GABA-A agonist
Onset= 30-60 seconds
Duration= 5-15 minutes
pKa=
Etomidate
Clearance=
Active metabolite=
Induction dose=
Clearance= Liver + plasma esterases
Active metabolite= none
Induction dose= 0.2-0.4 mg/kg
Etomidate
Respiratory effects=
CV effects=
CNS effects=
Respiratory effects= mild respiratory depression
CV effects= minimal
CNS effects= decreased ICP, no analgesia
Chemical name and class of etomidate
Chemical name= R-1-methyl-1-(a-methylbenzyl) imidazole-5-carboxylate
Class=Imidazole
How does the imidazole etomidate function in different pH’s
Acidic pH = imidazole ring opens = INCREASED H2O solubility
Physiologic pH = imidazole ring closes = INCREASED lipid solubility
Describe the clearance of etomidate
Liver P450 enzymes and plasma esterases