General Anesthesia: Pharmacological Principles, Mechanisms, Clinical Applications, Safety, and Recent Advances

Abstract

General anesthesia is a controlled, reversible state of unconsciousness produced pharmacologically to facilitate surgical and diagnostic procedures while preventing awareness, pain, movement, and undesirable autonomic responses. Modern general anesthesia is usually achieved through a combination of intravenous and inhalational anesthetic agents, analgesics, neuromuscular blocking drugs, and supportive medications. The pharmacological basis of general anesthesia involves modulation of several molecular targets, particularly γ-aminobutyric acid type A (GABA_A), N-methyl-D-aspartate (NMDA), glycine, nicotinic acetylcholine, potassium, and other ion channels. Rather than acting through a single mechanism, anesthetic agents produce distinct components of the anesthetic state—including unconsciousness, amnesia, analgesia, and immobility—through actions at different sites within the central and peripheral nervous systems. Common intravenous agents include propofol, etomidate, ketamine, and barbiturates, whereas sevoflurane, desflurane, and isoflurane are important inhalational agents. Safe anesthesia requires appropriate preoperative assessment, airway management, cardiovascular and respiratory monitoring, temperature management, and postoperative surveillance. Recent advances include improved understanding of neural circuits, target-specific anesthetic development, pharmacokinetic-guided drug delivery, processed electroencephalographic monitoring, and development of rapidly metabolized “soft” anesthetic agents. This review summarizes the pharmacological principles, mechanisms, clinical applications, safety considerations, and emerging developments in general anesthesia.