General Anesthetics

Question 1

MoA of Anesthetic drugs

Answer 1

1) Inhibition of nicotinic receptor isoforms at moderate to high concentrations → most inhaled anesthetics
2) GABA-mediated inhibition at GABAA
receptors → inhaled anesthetics, barbiturates, benzodiazepines, etomidate, and propofol
3) Antagonising with glutamic acid on the NMDA receptors (e.g.ketamine).

Question 2

Give examples of inhaled Anesthetics

Answer 2

1) Nitrous Oxide (pediatric/Adult dental procedures)
2) Halothane (General An.)
3) Sevoflurane, Desflurane, Isoflurane
-ane

note: Sevoflurane is well tolerated by children with rapid onset

Question 3

Indication of Halothane

Answer 3

Inhaled General Anesthetic

Question 4

Adverse effects of Inhaled Anesthetics

Answer 4

1) CNS effects :
–> ↓ brain metabolic rate
–> ↓ vascular resistance and thus ↑ cerebral blood flow → ↑ intra-cranial pressure

2) Cardiovascular effects:
* ↓ arterial BP moderately
* Some can ↓ cardiac output
* ↓ blood flow to liver and kidney

3) Respiratory:
Decreased ventilatory response to hypoxia (most inhaled anesthetics are bronchodilators)

4) Toxicity
* Renal insufficiency and hepatitis (halothane)
* Susceptible patients → malignant hyperthermia (muscle rigidity, tachycardia, hyperthermia, and metabolic acidosis)
–> Treat with supportive measurements + muscle relaxant: dantrolene

Question 5

Adverse effects of Halothane

Answer 5

• Renal insufficiency
• Hepatitis

Question 6

PK/PD of Halothane

Answer 6

1. Metabolized by CYP450.
2. Tolerated by children.
3. Bronchodilator
4. high blood and lipid solubility, high
   potency, slow induction

Question 7

Indications of Nitrous Oxide

Answer 7

Inhaled Anesthetic used in:
1. Pediatric/ Adult dental procedures

Question 8

MoA of Inhaled Anesthetics

Answer 8

Effects on ion channeles by interaction w/ membrane lipids

Question 9

PK/PD of Nitrous Oxide

Answer 9

1. Reduce pain sensation.
2. Induce amnesia.

Question 10

Adverse effects of Nitrous Oxide

Answer 10

1) Postoperative Nasuea and vomiting
2) Induces sleepniess
3) Shivering and sweating

Question 11

Administration of Parenteral Anesthetics?

Answer 11

Via IV route

Question 12

Give examples of Parenteral Anesthetics

Answer 12

1) Thiopental (Barbi)
2) Proprofol (GABA receptor agonist)
3) Etomidate (GABAa receptor agonist)
4) Ketamine (NMDA glutamate antagonsit)

Question 13

Indication of Thiopental

Answer 13

Inducing agent for surgical anesthesia

Question 14

MoA of Thiopental

Answer 14

increases Chloride ion channel openning duration by acting on GABAa ion channel complex

Question 15

PK/PD of Thiopental

Answer 15

1. only barbi used in anesthetics
2. Very high lipid solubility –> fast onset.
3. Redistribution occurs –> tissues with large blood supply; then muscles.

Question 16

AE of Thiopental

Answer 16

Profound respiratory depression

Question 17

Indication of Propofol

Answer 17

Maintenance anesthetic in inpatient & outpatient surgery

Question 18

Category of Propfolol

Answer 18

GABAa receptor Agonist

Question 19

PK/PD of Propofol

Answer 19

1. Rapid anesthesia (induction agent).
2. Rapid recovery

Question 20

AE of Propofol

Answer 20

CNS & Cardiac depressant –> causes hypotension (↓ Peripheral Resistance)

Question 21

Indication of Ketamine

Answer 21

Regional or Local anesthetic procedures.

Question 22

Category of Ketamine

Answer 22

NMDA glutamate antagonist

Question 23

MoA of Ketamine

Answer 23

Inhibits excitation by glutamate at NMDA
receptors.

Question 24

AE of Ketamine

Answer 24

1. Disorientation.
2. Excitation.
3. Hallucinations.

Question 25

PK/PD of Ketamine

Answer 25

1. **Cardiovascular stimulant --> ↑ intracranial pressure** 2. **Slow recovery**. 3. Patients may be conscious but has marked catatonia, analgesia and amnesia

Question 26

Indication of Etomidate

Answer 26

1. Used for General anesthesia. 2. Sedation for **short procedures**. 3. Preferred in **patients with circulatory failures.**

Question 27

Category of Etomidate

Answer 27

GABAa receptor Agonist

Question 28

PK/PD of Etomidate

Answer 28

1. Rapid induction. 2. **Short duration of action** 3. no analgesic properties. 4. Less likely of prolonged hangover (metabolism). 5. **minimal change in cardiac and resp. functions**.

Question 29

PK/PD of Etomidate

Answer 29

1. Rapid induction. 2. Short duration of action. 3. no analgesic properties. 4. Less likely of prolonged hangover (↑ metabolism). 5. minimal change in cardiac and resp. functions.

Question 30

Vital sign monitoring → assessing depth of anesthesia during surgery → --------------------

Answer 30

eyelash reflex.