Pharm Flashcards
Exam II
A drug that reversibly depresses the activity of the CNS
Sedative-Hypnotics
A drug that reduces anxiety and that has sedation as a side effect
Anxiolytic
What are Vessel-poor groups? What % of CO do they receive?
- Bone
- Tendon
- Cartilage; 2%
Fat recieves how much CO?
5%
What muscle groups receive how much CO? What %?
- Skeletal muscle
- Skin; 18%
What are the vessel-rich groups? What % of CO do they receive?
- Brain
- Heart
- Kidney
- Liver ; 75%
What are the 4 stages of general anesthesia?
- Analgesia
- Delirium
- Surgical Anesthesia
- Medullary Paralysis
What are the 5 components of general anesthesia?
- Hypnosis
- Analgesia
- Muscle Relaxation
- Sympatholysis
- Amnesia
It starts with the initiation of an anesthetic agent and ends with the loss of conciousness
Stage 1: Analgesia
It starts with the loss of consciousness to the onset of automatic rhythmicity of vital signs.
Stage 2: Delirium
It starts with the absence of response to surgical incision and depression in all elements of nervous system function.
Stage 3: Surgical Anesthesia
It starts with cessation of spontaneous respiration and medullary cardiac reflexes.
Stage 4: Medullary Paralysis
The lightest level of anesthesia
Stage 1: Analgesia
Rapid stage that is chracterized by excitement, movements, laryngospasm, and emesis
Stage 2: Delirium
Stage associated with flaccid paralysis, absent reflexes, and marked hypotension with a weak, irregular pulse
Stage 4: Medullary Paralysis
What are the 4 induction drugs?
- Barbituates
- Propofol
- Etomidate
- Ketamine
What drug is the gold standard for comparison with other drugs?
Barbituates
What is the MoA of Barbituates?
Potentiate GABAA channel activity; directly mimics GABA
What other receptors do barbituates work on besides GABAA?
- Glutamate
- Adenosine
- Neural nACh
Barbiturates are cerebral vaso_____. They ______ CBF and ______ CRMO2 by 55%
vasoconstrictors; decrease; decrease
Barbituates have a lengthy…
context-sensitive half-time
Barbiturates have a ____ onset & _____ awakening d/t ____ uptake and ____ redistribution
rapid; rapid; rapid; rapid
How are barbituates dosed?
Dosed on LEAN body weight
What is the primary metabolism mechanism for barbituates?
Liver Hepatocytes
What drug is given rectally with uncooperative/young patients?
Barbituates
Which barbituates are the thiobarbituates?
- Thiopental
- Thiamylal
Which barbiturates are the oxybarbiturates?
- Methohexital
- Phenobarbital
- Pentobarbital
What is the dose for Thiopental (Sodium Pentothal)? How is the dose calculated?
4 mg/kg IV; IBW
Describes the distribution of a given agent at equilibrium between two substances at the same temperature, pressure, and volume
Partition Coefficients
Describes the distribution of an anesthetic between blood and gas at the same partial pressure
Blood-gas coefficient
Which barbiturates have oxygen in the second position?
Oxybarbiturates
What gives thiobarbiturates more hypnotic potency and lipid solubility?
Sulfur atom in place of the oxygen atom in the second position.
What are two side effects of methohexital?
- Myoclonus
- Hiccoughs
What is the dose for Methohexital (Brevital)
1.5 mg/kg IV
What are the primary CV effects of barbiturates?
- Lack of baroreceptor response
- Histamine release - anaphylactoid response with previous exposure
- Transient decreases in BP
- Trainsent increase in HR
What are the primary respiratory effects of barbituates?
Dose-dependent depression of ventilatory centers
Results in immediate, intense vasoconstriction and excruciating pain that radiates along the distribution of the artery
Intra-arterial injection of barbiturates
What’s the antidote for an intra-arterial injection of barbiturates?
Licodaine or papaverine
What is the MoA for propofol?
GABA receptor agonist
What’s the induction dose for propofol?
1.5-2.5 mg/kg IV
What’s the conscious sedation dose of propofol?
25-100 mcg/kg/min
What is the constitution of a 1% solution of propofol?
- Soybean oil (10%)
- Glycerol (2.25%)
- Purified egg phosphatide (1.2%)
What are the 3 primary disadvantages of propofol?
- Support bacterial growth
- Causes increased plasma triglyceride concentrations
- Pain on injection
What happens when propofol binds to a GABAA receptor?
Transmembrane chloride conductance increases
What is the elimination 1/2 time of propofol?
0.5-1.5 hours
A low lipid emulsion with no preservative and higher incidence of pain on injection.
Ampofol
What are 3 potential contraindications or precautions with propofol use?
- Cirrhosis of the liver
- Renal dysfunction
- Pregnancy and the neonate
What are the two primary uses for propofol?
- Induction
- TIVA
Why do children require a higher dose of propofol?
Larger central distribution volume and faster clearance rate
- Minimal analgesic and amnestic effects
- Prompt recovery without residual sedation
- Low incidence of PONV
- Anticonvulsant
- Bronchodilation
Benefits of propofol
What are two notable case types that benefit from propofol use?
- Agent of choice in GI endoscopy procedures
- Mechanically ventilated patients in the ICU or postop (cardiac, neuro, etc.)
What is the MoA for propofol’s antiemetic effects?
It depresses subcortical pathways and has a direct depressant effect on the vomiting center
What’s the sub-hypnotic dose of propofol? Anti-pruritic?
10-15 mg IV followed by 10mcg/kg/min; 10mg
What are the 3 primary CNS effects of propofol?
- Decreases CRMO2, CBF, and ICP
- Larger doses decrease CPP
- Myoclonus
How does propofol cause its vasodilatory effects?
Inhibition of the SNS and decreases intracellular Ca2+
What does the green and cloudy urine from propofol come from?
- Phenols (Green)
- Uric acid crystallization (Cloudy)
What are two severe side effects of propofol?
- Profound bradycardia and asystole in healthy adult patients
- Severe, refractory, and fatal bradycardia in children
What causes pain at the injection site with etomidate?
Propylene glycol
What’s the onset for Etomidate?
1 min
What’s the dose for Etomidate?
0.3mg/kg
What’s the MoA for Etomidate?
Selective modulator of GABAA receptors
What is the best patient population to use Etomidate with?
Patient’s with unstable CV system
What are two of the primary side effects of Etomidate?
- Myoclonus
- Adrenocortical Suppression
How often does myoclonus happen in patients given Etomidate?
50-80%
What are two contraindications to using etomidate?
- Sepsis
- Hemorrhage
How is Etomidate metabolized?
Hydrolysis by hepatic microsomal enzymes and plasma esterases
What happens with adrenocortical suppression?
- No stress response (no cortisol)
- Enzyme inhibition for 4-8 hours
- Severe hypotension
- Longer mechanical ventilation
Fentanyl 50mcg/mL is available. Patient is 75kg. Administer 1mcg/kg to attenuate myoclonus. How many mLs will you administer?
1.5 mLs
What is ketamine a derivative of?
PCP
It resembles a cataleptic state in which eyes remain open with a slow nystagmic gaze. The patient is uncommunicative, but wakefulness is present. Purposeful movement.
Dissociative anesthesia
What is the preservative in ketamine?
Benzethonium Chloride
What is the MoA for Ketamine?
Inhibit uptake of catecholamines back into the postganglionic sympathetic nerve endings
What receptors to ketamine bind to?
N-Methyl-D-aspartate (NMDA) receptors
What is the most abundant excitatory neurotransmitter in CNS?
Glutamate
What are the pharmacokinetics of Ketamine?
- Rapid onset
- Short duration of action
- Large Vd - highly lipid soluable
How long does ketamine last?
10-20 minutes
When is ketamine’s peak plasma concentration?
1 minute
What is norketamine?
Active metabolite of Ketamine (1/3 potency)
What is the induction dose for ketamine?
0.5-1.5 mg/kg IV
What is the subanesthetic dose for Ketamine?
0.2-0.5 mg/kg IV
What induction drug has weak actions at GABAA receptors?
Ketamine
Besides NMDA, what are the other receptors that Ketamine works on?
- Mu
- Kappa
- Delta
What are the neuraxial doses of Ketamine?
30 mgs Epidural
5-50 mg in 3mLs of saline intrathecal/spinal
Ketamine 25mgs/mL is available. How much diluent should be used to decrease the concentration to 5mgs/mL?
4 mLs
What is the coronary artery disease cocktail?
- Diazepam 0.5mg/kg IV
- Ketamine 0.5 mg/kg IV
- Continuous ketamine infusion mcg/kg/min
What are some of the nonanesthesia clinical uses for ketamine?
- Burn dressing, debridement, grafting
- Psychiatric disorders
- Reversal of opioid tolerance
What are the contraindications for ketamine?
- PHTN
- Increased ICP
What are some issues ketamine can cause during induction? How are they prevented/treated?
Coughing and laryngospasm; give an antisialoagogue or Glycopyrrolate