Ondansetron for neuraxial morphine-induced pruritus: A meta-analysis of randomized controlled trials

Ondansetron for the Prevention of Pruritus in Women Undergoing Cesarean Delivery With Intrathecal Opioid: A Systematic Review and Meta-Analysis

BACKGROUND

Pruritus is a frequently reported and unpleasant side effect following intrathecal opioid use with frequency further increased among parturients. We have performed a systematic review to assess the overall efficacy of ondansetron for the prevention of pruritus in patients receiving intrathecal opioid as part of spinal anesthesia for cesarean delivery.

METHODS

A literature search of MEDLINE, Embase, Cochrane, and Web of Science databases was conducted from date of inception to September 2022. Studies that included patients undergoing cesarean delivery with spinal anesthesia using intrathecal opioid were included. The primary outcome was the presence of pruritus, and the secondary outcome was time to onset of pruritus. Data from included studies were pooled for analysis using an appropriately determined random-effects model. Outcomes were presented using forest plots and 95% confidence intervals. Additional sensitivity and subgroup analysis were performed. Trial sequential analysis was conducted for the primary outcome.

RESULTS

Twenty-three randomized controlled trials with a total of 2586 patients were included: 1219 received ondansetron, 1030 received a placebo, and a further 337 received a different study drug and were excluded from analysis. Opioids used in the included studies were morphine, fentanyl, and sufentanil. Patients who received ondansetron showed a significant reduction in the incidence of pruritus compared to the control group (RR, 0.81; 95% confidence interval [CI], 0.71-0.92; I 2 = 64%). There was no significant difference in pruritus onset between the groups (mean difference [MD], 17.54 minutes; 95% CI, -2.18 to 37.26; I 2 = 83%). The overall Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessment of quality of evidence was low.

CONCLUSIONS

This systematic review has demonstrated a significant reduction in the incidence of pruritus following the use of ondansetron. This is in contrast to previously published meta-analyses. Studies included were of varying quality and some at high risk of bias with a high degree of statistical heterogeneity. Furthermore, high-quality and well-powered studies are required to confirm these findings.

Prevention and Treatment of Neuraxial Morphine-Induced Pruritus: A Scoping Review

The addition of morphine to neuraxial anaesthesia leads to improved postoperative analgesia and lower opioid consumption, but is often accompanied by pruritus. Studies on preventing or treating pruritus show contradictory results. Our objective was to identify effective drugs for the prevention or treatment of pruritus by a scoping review of clinical trials. A systematic literature search was conducted in PubMed, Embase and Web of Science. We identified clinical trials investigating the prevention or treatment of neuraxial morphine-induced pruritus in adults. Systematic reviews and meta-analyses were screened for eligible studies. One-hundred-and-four articles were included covering 13 pharmacological groups. We conclude that dopamine antagonists, µ-opioid agonist/antagonists and neuraxial or orally administered µ-opioid antagonists prevent pruritus caused by neuraxial morphine regardless of the timing of administration. In the reviewed literature, 5HT3-antagonists prevent neuraxial morphine-induced pruritus when administered before morphine administration. For the treatment of neuraxial morphine-induced pruritus, only nalbuphine appears to be consistently effective. More research is needed to find the most effective doses and the optimal timing of the effective medication.

Uremic Pruritus: From Diagnosis to Treatment

Uremic pruritus, or chronic kidney disease-associated pruritus, is common, bothersome, and sometimes debilitating in patients with chronic kidney disease or end-stage renal disease. Due to its variable clinical manifestations, the diagnosis of uremic pruritus requires exquisite evaluation. Excluding itch resulting from other dermatological causes as well as other systemic conditions is essential for a proper diagnosis. The pathophysiology of uremic pruritus remains uncertain. Hypotheses including toxin deposition, immune system dysregulation, peripheral neuropathy, and opioid imbalance are supposed. This review summarizes the way to accurately diagnose uremic pruritus and describes the latest treatment options.

In Vitro Inhibition of Renal OCT2 and MATE1 Secretion by Antiemetic Drugs

The organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1) mediate the renal secretion of drugs. Recent studies suggest that ondansetron, a 5-HT₃ antagonist drug used to prevent nausea and vomiting, can inhibit OCT2- and MATE1-mediated transport. The purpose of this study was to test the ability of five 5-HT₃ antagonist drugs to inhibit the OCT2 and MATE1 transporters. The transport of the OCT2/MATE1 probe substrate ASP⁺ was assessed using two models: (1) HEK293 kidney cells overexpressing human OCT2 or MATE1, and (2) MDCK cells transfected with human OCT2 and MATE1. In HEK293 cells, the inhibition of ASP⁺ uptake by OCT2 listed in order of potency was palonosetron (IC₅₀: 2.6 μM) > ondansetron > granisetron > tropisetron > dolasetron (IC₅₀: 85.4 μM) and the inhibition of ASP⁺ uptake by MATE1 in order of potency was ondansetron (IC₅₀: 0.1 μM) > palonosetron = tropisetron > granisetron > dolasetron (IC₅₀: 27.4 μM). Ondansetron (0.5–20 μM) inhibited the basolateral-to-apical transcellular transport of ASP⁺ up to 64%. Higher concentrations (10 and 20 μM) of palonosetron, tropisetron, and dolasetron similarly reduced the transcellular transport of ASP⁺. In double-transfected OCT2-MATE1 MDCK cells, ondansetron at concentrations of 0.5 and 2.5 μM caused significant intracellular accumulation of ASP⁺. Taken together, these data suggest that 5-HT₃ antagonist drugs may inhibit the renal secretion of cationic drugs by interfering with OCT2 and/or MATE1 function.

Acupuncture for reducing pruritus induced by intrathecal morphine at elective cesarean delivery: a placebo-controlled, randomized, double-blind trial

BACKGROUND

Intrathecal morphine is a standard postoperative analgesic administered after cesarean delivery, but frequently causes pruritus. Acupuncture reportedly resolves refractory pruritus in certain patients. The aim of the study was to investigate the effectiveness of acupuncture in preventing pruritus induced by intrathecal morphine.

METHODS

Thirty parturients received intrathecal hyperbaric bupivacaine (12 mg), fentanyl (10 µg), and morphine (150 µg) for spinal anesthesia at elective cesarean delivery at term. Patients were randomly divided into the acupuncture group (n=15) and the control group (n=15). In the acupuncture and control groups, certified acupuncturists inserted either indwelling press needles or sham needles, into Hegu (LI4), Neiguan (PC6), Quchi (LI11), and Zhigou (SJ6) on both arms the day before surgery. Needles were removed 48 hours postoperatively. The primary outcome was the incidence of postoperative pruritus. Adverse effects including nausea and vomiting were also investigated.

RESULTS

There were no significant differences between the acupuncture group and the control group in the incidence of pruritus (67% vs. 67%, P=1.000, RR 1.0 [95% CI 0.60 to 1.66]) or the requirement for antipruritic therapy (6.7% vs. 20.0%, P=0.283, RR 0.33 [95% CI 0.04 to 2.85]). The incidence of postoperative nausea in the acupuncture group versus control group was 40.0% vs. 13.3%, P=0.099, RR 3.0 [95% CI 0.72 to 12.6]). The postoperative analgesic effect was comparable.

CONCLUSION

Preoperatively administered acupuncture using press needles did not decrease intrathecal morphine-induced pruritus or the requirement for treatment.

Is There a Role for 5-HT3 Receptor Antagonists in the Treatment of Opioid-Induced Pruritus?

Pruritus is an unpleasant irritation symptom that can be related to various systemic and dermatological conditions. Although underreported, pruritus is a common adverse event noted after use of opioid pain medications. This article reviews the current understanding of the mechanism of opioid-induced pruritus (OIP) and various pharmacological therapies. 5-Hydroxytryptamine 3 (5-HT₃) receptor antagonists are potentially effective for treating OIP and may be a valuable treatment option if further controlled studies are encouraging.