Wk 1-Inductions & Benzos Flashcards
Define: Sedative
a drug that induces a state of calm or sleep, still arousable
What is an example of a sedative procedure?
MAC
Define: Hypnotic
a drug that induces hypnosis or sleep, form of disassociation from the environment
Define anxiolytic.
any drug that reduces anxiety
What is is sedative-hypnotics?
collective term, drugs that reversibly depress the activity of the CNS. This class of drugs play an important role in every aspect of anesthesia delivery from conscious sedation to general anesthesia
Define general anesthesia.
drug-induced unconsciousness that abolishes conscious memory as one component
What is the triad of general anesthesia?
amnesia, muscle relaxation, analgesia
The ______ have greater potency then the sedative effects.
Amnestic potency
What drug is important in the recall of events during general anesthesia and child birth? Why?
Benzodiazepines, Important consideration when concerned with “recall” of events (conscious memory) during anesthesia, especially during procedures that require general anesthesia.
But also an important consideration for events (as childbirth) where a patient’s memory of the event is warranted.
Define anterograde amnesia.
After receiving a drug
Define retrograde.
Before giving the drug
Benzos will _______ the GABA (A) receptor’s affinity for GABA
increase
Define an allosteric modulator
the binding of a substance(called an allosteric modulator) to a certain site on a receptor in a way that alters the conformation of other sites on the receptor, thereby increasing or decreasing the affinity of the receptor for other molecules.
γ-Aminobutyric acid type A (GABAA) receptors are inhibitory or excitatory
inhibitory CNS receptors in neurons, and major targets of general anesthetics such as etomidate and propofol.
What do GABAa receptors contain?
five subunits arranged around a chloride-conducting pore
_____ subunits account for the anxiolysis, whereas _______ account for the sedative, amnestic and anticonvulsive
α2; a1
States of _______ and ______ can increase bioavailability.
Hypoalbumenia/liver disease
What are the common side effects of benzos?
Fatigue, drowsiness (most common)
What is of concern with elderly taking benzos?
Concern with cognitive disturbances postoperative in the elderly.
What are some physiological changes that make the elderly more sensitive to benzos (6)?
aging brain with memory impairment and age related changes in CNS receptors. Decreased metabolism and clearance of drugs. Also increase in body fat and age-related decreases in serum albumin (more unbound drug available)
What other agents can produced synergistic sedative effects in combo with benzos?
ETOH, inhaled and injected anesthetics, opioids, and alpha2 agonists
What can happen with benzos and ETOH?
Life threatening CNS depression when used in conjunction with ETOH (they have cross tolerance).
What meds are used to treat alcohol withdrawal?
Lorazepam (Ativan) and valium
Do you have a burning sensation with midazolam?
No, easily well tolerated
What is true regarding midazolam and pregnancy?
Teratogenic concerns (cleft palate): Pregnancy test on all childbearing woman before administering (or waiver)
What is the pKa of midazolam?
6.2
What is the metabolite produced by midazolam biotransformation?
1-hydroxymidazolam: ½ activity of parent
What is an imidazole ring?
Imidazole ring: midazolam exists with both an “open structure” that is protonated to allow for aqueous suspension and the “closed structure” that is physiologic active, highly lipophilic. Structure changes with pH of environment (gastric or IV) favoring the more “closed” form
What effect dose increased vd have on infusion rate?
Increased Vd may require a higher initial infusion rate at initiation
Where is midazolam metabolized?
CYP 3A4
What dose of midazolam can cause transient apnea, especially in the presence of opioid?
> 0.05 mg/kg
What phases of biotransformation will midazolam undergo?
Glucuronamide conjugation and oxidative hydroxylation
What is the pediatric dosing of midazolam?
0.25-0.5mg/kg
How often before induction should midazolam be given prior to induction, in pediatrics?
20-30 minutes
What is the IV sedation adult dose of midazolam ?
1.0-2.5mg IV
What is the half-time peak effect of midazolam?
5.6 minutes
What is the duration of IV sedation midazolam?
15-80 minutes
What is the anesthesia induction dose of midazolam?
0.1-0.2mg/kg IV
What is the loading and maintenance dose of postop midazolam sedation?
- 0.5-4.0 mg IV loading dose
- Maintenance 1-7 mg/hour IV (for postop intubated patients)
What is the adult dosing range of paradoxical vocal cord motion (postop stridor)?
0.5-1 mg IV
Onset IV (min of midazolam)
0.5-1 min
Onset IV (min of Diazepam)
1-5 min
Onset IV (min of lorazepam)
1-3 min
pKa (midazolam)
6.57
pKa (diazepam)
3.4
pKa (Lorazepam)
11.5
vD (midazolam)
1.1 L/Kg
vD (Diazepam) L/Kg
1.1 L/Kg
vD (Lorazepam) L/Kg
1.3 L/Kg
Clearance (midazolam) mL/kg/min
1.6 mL/kg/min
Clearance (Diazepam) mL/kg/min
0.38 mL/kg/min
Clearance (Lorazepam) mL/kg/min
1.1 mL/kg/min
Midazolam (Elimination 1/2 time)
1.9 hours
Diazepam (Elimination 1/2 time)
43 hours
Lorazepam (Elimination 1/2 time)
14 hours
Define elimination half-life
isthe length of time required for the concentration of a drug to decrease to half of its starting dose in the body
What is produced from the metabolism of Diazepam? What clinical significance does this have?
- Prolonged duration of action
- Active metabolite: desmethyldiazepam
What is the elimination half-time in healthy patients for diazepam?
40 hours
What is the MOA of flumazenil?
Specific BZO GABAA receptor antagonist (competitive)
What is the initial dose of flumanezil?
Recommended initial dose 0.2mg IV (8-15mcg/kg IV)
What is the recommended additional dose of flumazenil?
If needed, additional doses of 0.1mg IV (total dose of 1 mg) at 60 second intervals
What is the duration of action of Flumazenil?
30-60 minutes
Peak effects of Flumazenil can be seen in ______ minutes. What is the approximate half life?
1-3 minutes; 1 hr
What is the drug classification for demedetomidine?
Potent, highly selective alpha 2-adrenergic receptor agonist
What is the site of action that dexmedtomidine exerts its effects?
Pontine Locus Coeruleus (brainstem)
What is clonidine?
Clonidine is partial agonist with less selectivity for alpha 2 as compared to Dex which is a full agonist with much higher selectively
What is the elimination half-time of dexmedetomidine?
2-3 hours
How is dexmedetomidine metabolized?
Undergoes extensive hepatic metabolism (slightly inhibits enzymes): N-glucuronidation
& P450 Hydroxylation
Does dexmedetomidine suppress respiratory function?
No
What are the major cardiovascular side effects of dexmedetomidine?
Bradycardia and hypotension
What is formed through the biotransformation of Flumazenil?
Inactive metabolites
What is the main goal of induction agents?
IV medications that lead to rapid loss of consciousness
What is TIVA?
TIVA: total intravenous anesthesia- a technique for providing anesthesia
What is the steps to induction?
Provide sedation, Induce (start) general anesthesia - usually in combination w/ other drugs, Used as the sole anesthetic drug for some procedures, Maintain a state of anesthesia for longer procedures via infusion.