Nalbuphine an equally effective intrathecal adjuvant as fentanyl for spinal anesthesia

For lower limb procedures, local anesthetic medications like bupivacaine and ropivacaine are widely utilized through intrathecal route to give good analgesia and sensory block. Among traditional local anesthetics, hyperbaric bupivacaine has the added benefit of a longer period of effective blockage and pain reduction, as well as improved control over the amount of blockade accomplished. When added to local anesthetics, adjuvants such as opioids and alpha 2 agonists increase the duration of block and offer postoperative pain relief while limiting the usage of high doses of local anesthetic. Intrathecal adjuvants are used in conjunction with local anesthetics to extend the length of the procedure and give postoperative pain relief while reducing the local anesthetic dosage.

Fentanyl is a regularly used intrathecal adjuvant, with doses ranging from 10 to 50 micrograms. It has been shown to be a good way to extend the duration of sensory block and postoperative analgesia. Nausea, vomiting, pruritus, muscular stiffness, and respiratory depression are among adverse effects of fentanyl.

Nalbuphine is an agonist-antagonist opioid that delivers long-lasting analgesia with less fentanyl-related adverse effects such itching, nausea, and vomiting. Recently published study evaluated the safety and advantages of Nalbuphine via intrathecal route.

Sixty-six patients from the American Society of Anesthesiology (ASA) classes I and II who were scheduled for orthopedic lower limb surgery were included in the study. Patients were given 15 mg of hyperbaric bupivacaine intrathecally, along with 1 mg nalbuphine (group N), 25mcg fentanyl (group F), or 0.9 percent normal saline (group C). When compared to patients who received fentanyl, those who received intrathecal nalbuphine (group N) exhibited a considerably delayed onset of sensory and motor block (group F). When comparing group F (122.05+/- 10.65 minutes) to group N (114.55 +/- 10.90 minutes), the time to two segment regression was substantially longer in group F (122.05 +/- 10.65 minutes). [0.05] [P 0.05] [P 0.05] [P 0.05] [P The average length of motor blockage in group F (197.73+/- 15.09 minutes) was substantially longer than in group N (180.68 +/- 15.68 minutes). [P<0.05]. Group N (323.18 +/- 57.39 minutes) and group F (287.05 +/- 78.87 minutes) had similar spinal analgesia durations, both substantially longer than group C (224.32+/- 42.54 minutes). The hemodynamic effects, the need for 24-hour rescue analgesics, and the frequency of side effects were similar in groups N and F.

In terms of intramuscular and intravenous dose, nalbuphine is analgesic to morphine, with a comparable onset and duration of analgesia. Although nalbuphine suppresses respiration as effectively as an equianalgesic dosage of morphine, it has a ceiling impact on both analgesic and respiratory effects. The equivalent doses of nalbuphine and fentanyl are 2.5 mg and 25 mcg, respectively. There is no agreement on the dosage of nalbuphine should be given intrathecally for effective analgesia. When nalbuphine is employed as an adjuvant in subarachnoid block, the findings show that the analgesia it provides is comparable to that of fentanyl. In terms of duration of analgesia, postoperative analgesia needs, and incidence of adverse effects, it may be stated that nalbuphine is an equally effective intrathecal adjuvant as fentanyl.

Reference -

Sharma, Ankit,; Chaudhary, Sujata; Kumar, Mahendra; Kapoor, Ruchi Comparison of nalbuphine versus fentanyl as intrathecal adjuvant to bupivacaine for orthopedic surgeries: A randomized controlled double-blind trial, Journal of Anaesthesiology Clinical Pharmacology: Oct–Dec 2021 - Volume 37 - Issue 4 - p 529-536. doi: 10.4103/joacp.JOACP_270_18