Promethazine, a first-generation antihistamine, has gained significant recognition for its diverse pharmacological properties, including its utility in anesthesia. This phenothiazine derivative, best known for its antiemetic and sedative effects, is used in various medical settings to enhance the efficacy of anesthetic protocols. Promethazine has antihistamine, antiemetic, sedative, and anticholinergic properties, making it a valuable adjunct in perioperative care.
In the preoperative phase, promethazine is often administered to reduce anxiety and induce sedation. Its sedative effects are attributed to its central nervous system depressant activity, which is beneficial in calming patients prior to surgery. This preoperative sedation reduces the required dose of primary anesthetics, thereby minimizing potential side effects and improving overall patient safety (1). In addition, promethazine’s antiemetic properties are critical in preventing postoperative nausea and vomiting (PONV), a common complication of anesthesia. By blocking histamine H1 receptors and dopaminergic receptors in the chemoreceptor trigger zone, promethazine effectively reduces the incidence of PONV, improving patient comfort and recovery outcomes (2).
Promethazine’s antiemetic properties are particularly beneficial in certain patient populations, such as those undergoing chemotherapy or radiation therapy, who are at higher risk for nausea and vomiting. By proactively managing these symptoms with promethazine, clinicians can improve patient adherence to treatment regimens and overall quality of life (3). In addition, its use in pediatric anesthesia has been studied, where it can help manage anxiety and reduce the need for multiple anesthetic agents, thereby minimizing potential drug interactions and side effects (1).
Furthermore, promethazine’s anticholinergic activity contributes significantly to its utility in anesthesia. By inhibiting muscarinic receptors, promethazine reduces secretions, including saliva and airway mucus, which is particularly beneficial during surgical procedures requiring intubation and mechanical ventilation. This reduction in secretions not only allows for a clearer surgical field, but also reduces the risk of aspiration, thereby improving patient safety (3).
Promethazine also plays a critical role in synergizing with opioid analgesics. When used in combination with opioids, promethazine enhances analgesia, allowing lower doses of opioids to achieve the desired effect. In the context of the ongoing opioid crisis, this opioid-sparing effect helps reduce the risks associated with opioid use, such as respiratory depression and potential for abuse (4). The combination of promethazine with opioids represents a strategic approach to pain management in the perioperative setting.
Despite its many benefits, the use of promethazine in anesthesia is not without potential drawbacks. Adverse effects such as excessive sedation, hypotension, and anticholinergic side effects must be carefully monitored. In addition, promethazine’s potential to cause extrapyramidal symptoms, especially at high doses or in vulnerable populations, requires cautious use (1). Therefore, a thorough understanding of the pharmacokinetics and pharmacodynamics of promethazine is essential for its optimal use in anesthesia.
In summary, promethazine serves as a versatile adjunct in anesthesia, providing sedative, antiemetic, anticholinergic, and opioid-sparing benefits. Its ability to improve patient comfort, reduce anesthetic requirements, and mitigate PONV underscores its value in perioperative care. However, careful consideration of its potential side effects and individual patient assessment are essential to ensure safe and effective use. Continued research and clinical experience will further elucidate the optimal use of promethazine in the evolving field of anesthesia.
References
- Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill Education; 2013.
- Gan TJ. Risk factors for postoperative nausea and vomiting. Anesth Analg. 2006;102(6):1884-1898. doi:10.1213/01.ANE.0000219597.16143.4D
- Watcha MF, White PF. Postoperative nausea and vomiting. Its etiology, treatment, and prevention. Anesthesiology. 1992;77(1):162-184. doi:10.1097/00000542-199207000-00023
- Trescot AM, Helm S, Hansen H, et al. Opioids in the management of chronic non-cancer pain: an update of American Society of the Interventional Pain Physicians’ (ASIPP) Guidelines. Pain Physician. 2008;11(2 Suppl):S5-S62.