Local Anesthetics - Local anesthetic agents prevent nerve impulses without causing unconsciousness. - They bind to sodium channels within nerve fibers, preventing sodium from entering and stabilizing the cell membrane. - Local anesthetics can be ester-based (e.g., procaine, benzocaine) or amide-based (e.g., lidocaine, bupivacaine). - Ester local anesthetics are fast-acting but unstable in solution, while amide local anesthetics have a slower onset and longer duration. - Preservative-free local anesthetics are used for intrathecal injections.

General Anesthetics - General anesthetics induce a reversible loss of consciousness. - Inhaled agents, such as isoflurane and sevoflurane, are commonly used for induction and maintenance of general anaesthesia. - Volatile agents should be non-flammable, non-explosive, and lipid-soluble. - Nitrous oxide is a common adjuvant gas, while halothane has been largely discontinued due to shortcomings. - Inhaled anesthetics can be used alone or in combination with other medications to maintain anaesthesia.

Intravenous Agents - Barbiturates like thiopental and methohexital are ultra-short-acting and used to induce and maintain anaesthesia. - Benzodiazepines can be used for sedation before or after surgery and to induce and maintain general anaesthesia. - Propofol is commonly used intravenously to induce and maintain general anaesthesia. - Etomidate is primarily used in sick patients due to its favorable physiological effects. - Ketamine is infrequently used in anaesthesia but commonly used in emergency settings and with sick patients.

Comparison of Volatile Agents - Volatile agents are compared in terms of potency and blood/gas partition coefficient. - Potency is inversely proportional to the minimum alveolar concentration. - Lower blood/gas partition coefficient allows for faster titration of anaesthesia depth and emergence from anaesthesia. - Isoflurane, desflurane, sevoflurane, and nitrous oxide are agents in widespread current use. - Enflurane has not gained widespread popularity due to side effects.

Intravenous Opioid Analgesic Agents - Opioids are rarely used to induce anaesthesia due to unreliability and significant side effects. - They can produce unconsciousness but lack pain relief properties. - Intravenous opioids are commonly used for pain management during anaesthesia. - Examples of intravenous opioids include morphine, fentanyl, and hydromorphone. - Opioids should be used with caution due to the risk of respiratory depression.

Muscle Relaxants - Muscle relaxants are used after a patient is rendered unconscious to facilitate intubation or surgery. - Hyperkalemia can occur in burn patients, neuromuscular disease, and paralyzed patients, causing life-threatening arrhythmia. - Muscle aches are common in young muscular patients who mobilize soon after surgery. - Bradycardia may occur, especially with repeat doses of muscle relaxants. - Malignant hyperthermia is a potentially life-threatening condition in susceptible patients. - Suxamethonium apnea is a rare genetic condition that can lead to prolonged neuromuscular blockade. - Anaphylaxis is a potential complication of muscle relaxant use. - Histamine release can occur with certain muscle relaxants, such as Atracurium and Mivacurium. - Anaesthesia awareness is a disturbing complication where patients paralyzed may awaken during anaesthesia. - Neurological monitors can help decrease the incidence of anaesthesia awareness.

Intravenous Reversal Agents - Flumazenil reverses the effects of benzodiazepines. - Naloxone reverses the effects of opioids. - Neostigmine helps to reverse the effects of non-depolarizing muscle relaxants. - Sugammadex helps to reverse the effects of non-depolarizing muscle relaxants.