Pharmacokinetics
- Absorption: Via lungs → alveoli → blood → brain
- Distribution: Depends on blood-gas partition coefficient
- Low B/G coefficient = faster induction/recovery (e.g., Desflurane)
- High B/G coefficient = slower induction/recovery (e.g., Halothane)
- Elimination: Mostly exhaled unchanged; some undergo hepatic metabolism (e.g., Halothane)
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Potency – Minimum Alveolar Concentration (MAC)
- MAC: Concentration required to prevent movement in 50% of patients in response to surgical stimulus
- Lower MAC = higher potency
- Halothane MAC ≈ 0.75% (high potency)
- Nitrous oxide MAC ≈ 105% (low potency, can’t produce surgical anesthesia alone)
Inhalational Anesthetics
| Agent | Characteristics | Advantages | Disadvantages |
| Halothane | Potent, non-irritant, slow induction | Suitable for children | Hepatotoxicity, arrhythmias |
| Isoflurane | Pungent, stable cardiovascular profile | Good muscle relaxant | Respiratory tract irritation |
| Sevoflurane | Pleasant odor, rapid induction | Ideal for pediatric use | Risk of nephrotoxicity (Compound A) |
| Desflurane | Very fast induction/recovery | Outpatient surgeries | Pungent, airway irritation |
| Nitrous Oxide | Weak anesthetic, strong analgesic | Fast onset, safe | Diffusion hypoxia, B12 inactivation |
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