Neuro - Pharmacology (Anesthetics)

Question 1

CNS drugs must have either of what 2 properties?

Answer 1

CNS drugs must be lipid soluble (cross the blood-brain barrier) or be actively transported.

Question 2

Which property of drugs lead to rapid induction? What other effect can this property have?

Answer 2

Drugs with decreased solubility in blood = rapid induction and recovery times

Question 3

Which property of drugs causes increased potency? How does this potency relate to MAC?

Answer 3

Drugs with increased solubility in lipids = increase potency = 1/MAC

Question 4

What is MAC?

Answer 4

MAC = Minimal Alveolar Concentration (of inhaled anesthetic) required to prevent 50% of subjects from moving in response to noxious stimulus (e.g., skin incision)

Question 5

Give an example of a drug that has low blood and lipid solubility. What kind of induction and potency does it have?

Answer 5

N2O has low blood and lipid solubility, and thus fast induction and low potency

Question 6

Give an example of a drug that has high blood and lipid solubility. What kind of induction and potency does it have?

Answer 6

Halothane, in contrast, has high lipid and blood solubility, and thus high potency and slow induction

Question 7

What are 6 examples of inhaled anesthetics?

Answer 7

(1) Halothane (2) Enflurane (3) Isoflurane (4) Sevoflurane (5) Methoxyflurane (6) Nitrous oxide

Question 8

What is the mechanism of inhaled anesthetics?

Answer 8

Mechanism unknown.

Question 9

What are 4 effects of inhaled anesthetics?

Answer 9

(1) Myocardial depression (2) Respiratory depression (3) Nausea/Emesis (4) Increased cerebral blood flow (decreased cerebral metabolic demand)

Question 10

What is the name and definition of the life-threatening toxicity that can be caused by inhaled anesthetics? What other drug can cause this? Which inhaled anesthetic does NOT cause this?

Answer 10

Can cause malignant hyperthermia - rare, life-threatening hereditary condition in which inhaled anesthetics (except nitrous oxide) and succinylcholine induce fever and severe muscle contractions

Question 11

Again, what 2 substances can cause malignant hyperthermia? What is the treatment for malignant hyperthemia?

Answer 11

Inhaled anesthetics and succinylcholine; Treatment: Dantrolene

Question 12

What kind of drug is halothane? What toxicity is associated with it?

Answer 12

Inhaled anesthetic; Hepatotoxicity (halothane)

Question 13

What kind of drug is methoxyfurane? What toxicity is associated with it?

Answer 13

Inhaled anesthetic; Nephrotoxicity (Methoxyfurane)

Question 14

What kind of drug is enflurane? What toxicity is associated with it?

Answer 14

Inhaled anesthetic; Proconvulsant (enflurane)

Question 15

What kind of drug is nitrous oxide? What toxicity is associated with it?

Answer 15

Expansion of trapped gas in a body cavity (nitrous oxide)

Question 16

What are 5 examples of intravenous anesthetics?

Answer 16

(1) Barbiturates (2) Benzodiazepines (3) Arylcyclohexylamines (Ketamine) (4) Opioids (5) Propofol; Think: “B. B. King on OPIOIDS PROPOses FOOLishly”

Question 17

Which barbiturate is known as an intravenous anesthetic? What kind of potency, lipid solubility, and entry into the brain does it have?

Answer 17

Thiopental - high potency, high lipid solubility, rapid entry into brain.

Question 18

What type of drug is thiopental? What are 2 clinical uses for Thiopental?

Answer 18

Barbiturates; Used for induction of anesthesia and short surgical procedures

Question 19

How is the effect of thiopental terminated?

Answer 19

Effect terminated by rapid redistribution into tissue (i.e., skeletal muscle) and fat

Question 20

What effect does thiopental have on cerebral blood flow?

Answer 20

Decreases cerebral blood flow

Question 21

What is the most common drug used for endoscopy? What kind of drug is this? With what is it used adjunctively?

Answer 21

Midazolam most common drug used for endoscopy; IV anesthetic, Benzodiazepines; Used adjunctively with gaseous anesthetics and narcotics.

Question 22

What are 3 side effects of Benzodiazepines used as IV anesthestics?

Answer 22

May cause severe severe postoperative respiratory depression, low BP (treat overdose with flumazenil), and anterograde amnesia

Question 23

What type of drugs are Arylcyclohexylamines (Ketamine), and what is their mechanism?

Answer 23

PCP analogs that act as dissociative anesthetics. Block NMDA receptors.

Question 24

What effect do Arycyclohexylamines have on the cardiovascular system?

Answer 24

Cardiovascular stimulants

Question 25

What are 3 side effects of Arylcyclohexylamines (Ketamine)?

Answer 25

Cause (1) disorientation, (2) hallucination, and (3) bad dreams

Question 26

What effect do Arylcyclohexylamines (Ketamine) have on cerebral blood flow?

Answer 26

Increased cerebral blood flow

Question 27

What are 2 examples of opioids? With what are they used clinically, and for what purpose?

Answer 27

Morphine, fentanyl used with other CNS depressants during anesthesia

Question 28

What are 3 clinical uses for propofol?

Answer 28

Used for sedation in ICU, rapid anesthesia induction, and short procedures

Question 29

How does propofol compare to thiopental?

Answer 29

Less postoperative nausea than thiopental

Question 30

What receptor does propofol act on, and how?

Answer 30

Potentiates GABAa

Question 31

What are 3 examples of local anesthetics that are esters?

Answer 31

Esters - (1) Procaine, (2) Cocaine, (3) Tetracaine

Question 32

What are 3 examples of local anesthetics that are amides?

Answer 32

Amides - (1) LIdocaIne, (2) mepIvacaIne, (3) bupIvacIne (amIdes have 2 I's in name).

Question 33

What is the mechanism of local anesthetics? What do they bind preferentially, and what effect does this have?

Answer 33

Block Na+ channels by binding to specific receptors on inner portion of channel; Preferentially bind to activated Na+ channels, so most effective in rapidly firing neurons

Question 34

Describe the form of tertiary amine changes in penetration versus receptor binding.

Answer 34

Tertiary amines local anesthetics penetrate membrane in uncharged form, then bind to ion channels as charged form

Question 35

What are 2 clinical uses for local anesthetics?

Answer 35

(1) Minor surgical procedures (2) Spinal anesthesia

Question 36

What kind of local anesthetics are given if patient has an allergy to main kind? What is the main kind of local anesthetics?

Answer 36

If allergic to esters, give amides

Question 37

What are the 3 main toxicities of local anesthetics?

Answer 37

CNS excitation, Hypertension, Hypotension

Question 38

What type of drug is Bupivacaine? What is a toxicity associated with it?

Answer 38

Amide local anesthetics; Severe cardiovascular toxicity (bupivacaine)

Question 39

What type of drug is Cocaine? What is a toxicity associated with it?

Answer 39

Ester local anesthetics; Arrhythmias (cocaine)

Question 40

With what other drugs can local anesthetics be given? What effect(s) does (do) this have?

Answer 40

Can be given with vasoconstriction (usually epinephrine) to enhance local action - decreased bleeding, increased anesthesia by decreased systemic circulation

Question 41

What is the challenge of anesthetics in infected tissue, and why? What is the solution for this?

Answer 41

In infected (acidic) tissue, alkaline anesthetics are charged and cannot penetrate membrane effectively --> need more anesthetic.

Question 42

What is the order of the nerve blockade due to local anesthetics? Which factor predominates in determining this order?

Answer 42

Order of nerve blockade: small-diameter fibers > large diameter >. Myelinated fibers > unmyelinated fibers. Overall, size factor predominates over myelination such that small myelinated fibers > small unmyelinated fibers > large myelianted fibers > large unmyelianted fibers.

Question 43

What is the order of sensory loss upon use of local anesthetics?

Answer 43

Order of loss: (1) pain (2) temperature (3) touch (4) pressure

Question 44

A patient overdoses on Benzodiazepines and has a low BP as a result. How is this treated?

Answer 44

Treat overdose with flumazenil