Adjunctive anesthetic agents complement hypnotics and neuromuscular blockers by providing analgesia, sedation, and autonomic stability, thereby forming the cornerstone of balanced anesthesia. Among these, opioids remain the most widely used class, exerting their effects primarily through μ-opioid receptor activation to produce potent analgesia and attenuate sympathetic responses to surgical stimulation. The perioperative selection of specific opioids is guided by their pharmacokinetic properties: fentanyl, remifentanil, and sufentanil are preferred for intraoperative use due to their rapid onset and titratability, whereas hydromorphone and morphine provide prolonged postoperative analgesia. Methadone, with its long duration of action and multimodal mechanism, offers sustained analgesia and may reduce the development of opioid tolerance. Common opioid-related adverse effects include respiratory depression, constipation, pruritus, chest wall rigidity, and, in some cases, serotonin syndrome, particularly when combined with other serotonergic medications. Dexmedetomidine, a highly selective α2-adrenergic agonist, provides cooperative sedation resembling natural sleep, modest analgesia, and reduced opioid requirements without significant respiratory depression. It is particularly valuable for awake fiberoptic intubation, procedural sedation, and potential intensive care unit (ICU) delirium reduction. Its main limitations are bradycardia, blood pressure changes (both hypertension and hypotension), and insufficient amnestic or hypnotic depth to serve as a sole anesthetic agent. Local anesthetics act by blocking voltage-gated sodium channels, interrupting nerve conduction, and producing targeted analgesia. Amide agents such as lidocaine, ropivacaine, and bupivacaine are widely used in regional and neuraxial techniques, while intravenous lidocaine infusions offer systemic analgesic and anti-inflammatory benefits. Their major risk is local anesthetic systemic toxicity (LAST), classically presenting with seizures and cardiovascular collapse. Management of LAST should focus on supportive resuscitative efforts (e.g., airway support, hemodynamic support), lipid rescue therapy, and, in refractory cases, extracorporeal support modalities (e.g., VA extracorporeal membrane oxygenation (ECMO)). Together, opioids, dexmedetomidine, and local anesthetics allow anesthesiologists to reduce reliance on volatile agents, tailor analgesia to patient needs, and enhance recovery. For internists, familiarity with these agents explains perioperative analgesic strategies, postoperative complications such as delirium or respiratory depression, and the rationale for multimodal pain management.

Pharmacological Adjuncts and Special Medications: Opioids, Dexmedetomidine, and Local Anesthetics

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发表日期：

2026年

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Aibek Mirrakhimov

摘要

Adjunctive anesthetic agents complement hypnotics and neuromuscular blockers by providing analgesia, sedation, and autonomic stability, thereby forming the cornerstone of balanced anesthesia. Among these, opioids remain the most widely used class, exerting their effects primarily through μ-opioid receptor activation to produce potent analgesia and attenuate sympathetic responses to surgical stimulation. The perioperative selection of specific opioids is guided by their pharmacokinetic properties: fentanyl, remifentanil, and sufentanil are preferred for intraoperative use due to their rapid onset and titratability, whereas hydromorphone and morphine provide prolonged postoperative analgesia. Methadone, with its long duration of action and multimodal mechanism, offers sustained analgesia and may reduce the development of opioid tolerance. Common opioid-related adverse effects include respiratory depression, constipation, pruritus, chest wall rigidity, and, in some cases, serotonin syndrome, particularly when combined with other serotonergic medications. Dexmedetomidine, a highly selective α2-adrenergic agonist, provides cooperative sedation resembling natural sleep, modest analgesia, and reduced opioid requirements without significant respiratory depression. It is particularly valuable for awake fiberoptic intubation, procedural sedation, and potential intensive care unit (ICU) delirium reduction. Its main limitations are bradycardia, blood pressure changes (both hypertension and hypotension), and insufficient amnestic or hypnotic depth to serve as a sole anesthetic agent. Local anesthetics act by blocking voltage-gated sodium channels, interrupting nerve conduction, and producing targeted analgesia. Amide agents such as lidocaine, ropivacaine, and bupivacaine are widely used in regional and neuraxial techniques, while intravenous lidocaine infusions offer systemic analgesic and anti-inflammatory benefits. Their major risk is local anesthetic systemic toxicity (LAST), classically presenting with seizures and cardiovascular collapse. Management of LAST should focus on supportive resuscitative efforts (e.g., airway support, hemodynamic support), lipid rescue therapy, and, in refractory cases, extracorporeal support modalities (e.g., VA extracorporeal membrane oxygenation (ECMO)). Together, opioids, dexmedetomidine, and local anesthetics allow anesthesiologists to reduce reliance on volatile agents, tailor analgesia to patient needs, and enhance recovery. For internists, familiarity with these agents explains perioperative analgesic strategies, postoperative complications such as delirium or respiratory depression, and the rationale for multimodal pain management.