Nalbuphine is an intravenous medication that is used for analgesia or as an adjuvant to anesthesia [1]. It is often used as an alternative to opioids, owing to its robust analgesic and sedative effects and its avoidance of side effects – including vomiting, nausea, and itching – commonly observed following opioid use [1]. Currently, the FDA permits the use of nalbuphine to address moderate to severe pain that would otherwise demand opioid use, or when other analgesic treatments have failed to assuage pain sufficiently [2]. Beyond these official uses, physicians have administered nalbuphine to treat pains associated with childbirth, surgical abortion, and other significant procedures [2].
By activating the kappa opioid receptor, nalbuphine produces analgesia in its recipients [2]. However, nalbuphine is also a partial mu opioid receptor antagonist, which explains its comparatively lower incidence of respiratory depression, nausea, and pruritus than morphine and other opioids [2]. Nalbuphine also exhibits a capping effect, signifying that after surpassing a certain dosage , respiratory depression does not increase further [1]. It is fast-acting: analgesic effects are felt within two to three minutes following intravenous injection, or fifteen minutes after intramuscular or subcutaneous administration [2]. These effects typically persist for three to six hours [2].
Several studies have documented the safety and efficacy of nalbuphine compared to other analgesic medications, particularly in novel settings. For instance, Yu et al. conducted a meta-analysis on the efficacy of nalbuphine as an adjuvant to local spinal anesthetics [1]. By aggregating eighteen studies that included a total of 1,633 patients, Yu et al. found that nalbuphine was not significantly more effective than opioids when used as an adjuvant in this context, but did result in fewer occurrences of itching, low blood pressure, and shivering [1]. However, nalbuphine did result in longer-lasting analgesia and 2-segment sensory regression time in comparison to a control group without adjuvant [1].
As an adjuvant to spinal anesthesia, nalbuphine appears to be similarly satisfactory in managing labor pain. Sun and colleagues studied the differential effects of sufentanil and nalbuphine when provided as patient-controlled intravenous analgesia (PCIA) [3]. Patients in the nalbuphine group reported higher satisfaction scores, as well as improved pain scores at rest and uterine cramping scores 6, 12, and 24 hours after the surgery [3]. Adverse events and PCIA drug consumption did not differ significantly between the two groups [3]. Ultimately, these results indicate the suitability of nalbuphine in place of sufentanil when treating cesarean-section patients.
Fang et al. reported similar results in the context of surgical abortions in a 2021 study [4]. While the medications were comparable for multiple metrics, among them hemodynamic fluctuation and intraoperative analgesia, nalbuphine was superior in terms of intensity and incidence of pain following propofol injection, as well as patient satisfaction [4].
An interesting question that arises, especially after considering the Sun and Fang studies, is whether nalbuphine operates differently on male and female patients. A recent experiment analyzed the analgesic effects of intravenous nalbuphine on patients undergoing major abdominal surgery [5]. It indicated that female patients exhibit greater levels of analgesia than male patients after taking nalbuphine, which could support administering different dosages based on sex [5].
In conclusion, nalbuphine is a powerful medication that can effectively provide pain relief in several contexts. Because of its analgesic efficacy and relative safety compared to medications such as sufentanil, it should be an option considered by anesthetists when administering care.
References
[1] P. Yu, J. Zhang, and J. Wang, “Nalbuphine for spinal anesthesia: A systematic review and meta-analysis,” Pain Practice, vol. 22, no. 1, p. 91-106, April 2021. [Online]. Available: https://doi.org/10.1111/papr.13021.
[2] D. Larsen and C. V. Maani, “Nalbuphine,” StatPearls, Updated May 8, 2022. [Online]. Available: https://www.ncbi.nlm.nih.gov/books/NBK534283/.
[3] S. Sun et al., “Analgesic Effect Comparison Between Nalbuphine and Sufentanil for Patient-Controlled Intravenous Analgesia After Cesarean Section,” Frontiers in Pharmacology, vol. 11, p. 1-7, November 2020. [Online]. Available: https://doi.org/10.3389/fphar.2020.574493.
[4] P. Fang et al., “Comparison of Analgesic Effects between Nalbuphine and Sufentanil in First-Trimester Surgical Abortion: A Randomized, Double-Blind, Controlled Trial,” Pain and Therapy, vol. 11, p. 121-132, November 2021. [Online]. Available: https://doi.org/10.1007/s40122-021-00334-0.
[5] A. E. Ayad et al., “Influences of Gender on Intravenous Nalbuphine Actions After Major Abdominal Surgery: A Multicenter Study,” Pain and Therapy, vol. 10, p. 1215-1233, June 2021. [Online]. Available: https://doi.org/10.1007/s40122-021-00277-6.