Pharm - Gen Anesthetics - Kisby

Question 1

What are the 2 general classes of GA?

Answer 1

1. Inhalation - can be halogenated or non-halogenated

2. Intravenous

Question 2

What are some pharmacokinetic factors of inhalation GAs that affect depth of anesthesia?

Answer 2

1. Partial pressure = conc in blood or other tissues
2. Minimal alveolar concentration (inversely related to oil/gas coefficient)
3. Blood/gas partition coefficient (lower coefficient = faster induction & recovery and vice versa)
4. Oil/gas partition coefficient = lipid solubility (higher coefficient, more potent GA)

Question 3

What determines uptake and distribution of inhalation GAs?

Answer 3

• Uptake of GA into tissues is based on their perfusion & solubility
• Highly perfused tissues are the first to encounter inhaled GAs
• Solubility & small volume limit GA capacity

Question 4

What is the MOA of GAs?

Answer 4

• Enhance inhibitory postsynaptic channel activity (GABA & Glycine)
• Inhibit excitatory synaptic channel activity (nicotinic receptors & Glutamate)

Question 5

Nitrous Oxide

Answer 5

• Non-halogenated inhalation GA
• Weak anesthetic & good analgesic
• MOA: NMDA antagonist
• Caution: can cause diffusional hypoxia
• Abuse can lead to neuropathies & magaloblastic anemia

Question 6

Volatile Halogenated Agents

Answer 6

• Drugs: Isoflurane, Desflurane, Sevoflurane
• Reduce BP by assign N2O
• Depress ventilation
• SE: life-threatening malignant hyperthermia

Question 7

What are some general characteristics of IV GAs?

Answer 7

• Used to induce anesthesia & reduce the amount of inhalation anesthetics
• Rapid onset, short half-life, recovery due to redistribution
• Advantage: less CV depression

Question 8

Ketamine

Answer 8

• IV GA
• Dissociative anesthetic = catatonia, analgesia, w/o LOC
• Use: diagnostic & minor surgeries
• MOA: reduces excitation by blocking glutamate receptors (NMDA)
• SE: increases catecholamine release

Question 9

Propofol

Answer 9

• IV GA
• Most commonly used IV GA for induction & maintenance
• MOA: enhances inhibition by binding to GABA receptor

Question 10

What are some pre-anesthetic medications and what SE do they address?

Answer 10

1. Relieve anxiety - benzodiazepines
2. Provide analgesia - opioids
3. Prevent allergic reactions - antihistamines
4. Prevent nausea & vomiting - anti-emetics
5. Prevent muscle contractions - SM relaxants