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Clinical pharmacology of opioids: basic pharmacology
Published in Nigel Sykes, Michael I Bennett, Chun-Su Yuan, Clinical Pain Management, 2008
Sangeeta R Mehendale, Chun-Su Yuan
The existence of different types of opioid receptors, i.e. the mu, delta, and kappa receptors, makes the concept of an agonist–antagonist possible. These compounds are agonists to one type of opioid receptor, while an antagonist to another type. As an example, drugs in this class antagonize mu receptors, but act as agonists at kappa receptors. Semisynthetic: – phenanthrene derivatives: nalbuphine;– thebaine derivatives: buprenorphine.Synthetic: – benzomorphan derivatives: pentazocine, dezocine;– morphinan derivatives: butorphanol.
Advantages and feasibility of intercostal nerve block in uniportal video-assisted thoracoscopic surgery (VATS)
Published in Postgraduate Medicine, 2023
Analgesic drugs commonly used after chest surgery include NSAIDs, opioid analgesics, and acetaminophen. NSAIDs inhibit the synthesis of cyclooxygenase (COX) and prostaglandin (PG). Ketorolac tromethamine is a nonselective COX inhibitor administered intravenously. While it can reduce opioid dosage and related adverse effects such as nausea, vomiting, and excessive sedation, its main side effects include gastrointestinal bleeding and an increased risk of postoperative bleeding. In contrast, acetaminophen inhibits PG synthesis by acting on the central nervous system and has fewer side effects than NSAIDs. Acetaminophen is effective for mild to moderate pain and can enhance the analgesic effects of opioids or NSAIDs when used in combination, but high doses may lead to liver damage [25]. Opioids activate opioid receptors in the peripheral and central nervous systems, producing analgesia. Dezocine, an opioid receptor agonist, has a similar analgesic effect to morphine, but has a ceiling effect on both analgesic and side effects [26]. Dose escalation beyond a certain point does not increase analgesia but may increase the risk of side effects, such as respiratory depression. Combining dezocine with other types of analgesic drugs can have a synergistic effect. Ropivacaine is an amide local anesthetic that can enhance postoperative analgesia when combined with epinephrine. However, accidental injection into the bloodstream may cause immediate acute systemic toxicity. Therefore, caution must be exercised during administration to prevent iatrogenic collateral injury.