Pharmacological control of opioid-induced pruritus: a quantitative systematic review of randomized trials:

Refractory pruritus caused by sintilimab and its clinical management: A case report

Several immune related adverse events (irAEs) were reported with the wide application of immune checkpoint inhibitors (ICIs) in tumors. ICI-related skin reactions are the most common, which are manifested as maculopapules, rash, pruritus, vitiligo, psoriasis, and lichenoid rash.Among them, the incidence of pruritus is second only to maculopapule/rash, but both often co-exist. The severity of pruritus is mostly mild to moderate and can be relieved after symptomatic treatment with antihistamines. Symptoms are slightly relieved after conventional treatment in patients with severe pruritus, but it easily recurs and eventually develops into refractory pruritus.The patient's quality of life may be affected and may also be life-threatening. We report a case of a patient with postoperative recurrence of gallbladder neuroendocrine carcinoma,who developed refractory pruritus after sintilimab use, which was relieved after naloxone infusion after unsuccessful conventional drug therapy. By analyzing the treatment plan of this typical case of immune-related refractory pruritus after using sintilimab, this report discusses how clinical pharmacists can provide individualized treatment of patients by using their expertise and clinicians' cooperation and complementation in treating clinically difficult cases. This case report may be used as a reference in treating patients with refractory pruritus after the clinical use of sintilimab.

Mechanisms and treatment of opioid-induced pruritus: Peripheral and central pathways

BACKGROUND AND OBJECTIVE

Pruritus (also known as itch) is defined as an unpleasant and irritating sensation of the skin that provokes an urge to scratch or rub. It is well known that opioid administration can cause pruritus, which is paradoxical as itch and pain share overlapping sensory pathways. Because opioids inhibit pain but can cause itching. Significant progress has been made to improve our understanding of the fundamental neurobiology of itch; however, much remains unknown about the mechanisms of opioid-induced pruritus. The prevention and treatment of opioid-induced pruritus remains a challenge in the field of pain management. The objective of this narrative review is to present and discuss the current body of literature and summarize the current understanding of the mechanisms underlying opioid-induced pruritus, and its relationship to analgesia, and possible treatment options.

RESULTS

The incidence of opioid-induced pruritus differs with different opioids and routes of administration, and the various mechanisms can be broadly divided into peripheral and central. Especially central mechanisms are intricate, even at the level of the spinal dorsal horn. There is evidence that opioid receptor antagonists and mixed agonist and antagonists, especially μ-opioid antagonists and κ-opioid agonists, are effective in relieving opioid-induced pruritus. Various treatments have been used for opioid-induced pruritus; however, most of them are controversial and have conflicting results.

CONCLUSION

The use of a multimodal analgesic treatment regimen combined with a mixed antagonist and κ agonists, especially μ-opioid antagonists, and κ-opioid agonists, seems to be the current best treatment modality for the management of opioid-induced pruritus and pain.

SIGNIFICANCE

Opioids remain the gold standard for the treatment of moderate to severe acute pain as well as cancer pain. It is well known that opioid-induced pruritus often does not respond to regular antipruritic treatment, thereby posing a challenge to clinicians in the field of pain management. We believe that our review makes a significant contribution to the literature, as studies on the mechanisms of opioid-induced pruritus and effective management strategies are crucial for the management of these patients.

Opioid toxicity: histamine, hypersensitivity, and MRGPRX2

Insights into the pathophysiology of many non-immune-mediated drug reactions referred to as toxicities, sensitivities, intolerances, or pseudoallergies have resulted from research identifying the mastocyte-related G-protein-coupled receptor (GPCR) member X2 (MRGPRX2), a human mast cell receptor mediating adverse reactions without the involvement of antibody priming. Opioid-induced degranulation of mast cells, particularly morphine, provoking release of histamine and other preformed mediators and causing hemodynamic and cutaneous changes seen as flushing, headache and wheal and flare reactions in the skin, is an example of results of MRGPRX2 activation. Opioids including morphine, codeine, dextromethorphan and metazocine as well as endogenous prodynorphin opioid peptides activate MRGPRX2 at concentrations causing mast cell degranulation. Unlike the canonical opioid receptors, MRGPRX2 shows stereochemical recognition preference for dextro rather than levo opioid enantiomers. Opioid analgesic drugs (OADs) display a range of histamine-releasing potencies from the strong releaser morphine to doubtful releasers like hydromorphone and the non-releaser fentanyl. Whether there is a correlation between histamine release by individual OADs, MRGPRX2 activation, and presence or absence of adverse cutaneous effects is not known. To investigate the question, ongoing research with recently pursued methodologies and strategies employing basophil and mast cell tests resulting from MRGPRX2 insights should help to elucidate whether or not an opioid's histamine-releasing potency, and its property of provoking an adverse reaction, are each a reflection of its activation of MRGPRX2.

Preventing nausea and vomiting after gynecological laparoscopic surgery by patient-controlled intravenous analgesia with a naloxone admixture: A randomized controlled trial

BACKGROUND

Opioid-induced nausea and vomiting are common side effects of patient-controlled intravenous analgesia (PCIA). This study aimed to explore the inhibitory effect of a naloxone admixture on the incidence of sufentanil-induced postoperative nausea and vomiting (PONV).

METHODS

A total of 132 Uyghur American Society of Anesthesiologists I and II patients scheduled to undergo elective gynecological laparoscopic surgery were recruited; among these, 120 patients were enrolled and randomly allocated into 4 groups: patients receiving PCIA but no naloxone were included in the control group (group A); patients receiving PCIA with a low-dose naloxone admixture at 0.2 μg·kg-1·h-1 were included in group B; patients receiving PCIA with naloxone admixture at 0.4 μg·kg-1·h-1 were included in group C; patients receiving PCIA with naloxone admixture at 0.6 μg·kg-1·h-1 were included in group D. All patients were administered sufentanil at 0.04 kg-1·h-1, butorphanol at 2 kg-1·h-1, and dexmedetomidine at 0.08 kg-1·h-1 using a PCIA device within 2 days of surgery. The occurrence of nausea and vomiting, visual analogue scores for pain intensity, mean arterial pressure, heart rate, oxygen saturation, pruritus, lethargy, respiratory depression, etc, was recorded at 2, 8, 12, 24, and 48 hours postoperatively.

RESULTS

There was a significant difference in the PONV scores between the groups at 8, 12, and 24 hours after surgery (P < 0.01). At 8 and 12 hours, the score of group C/D was significantly lower than that of group A/B (P < 0.01). At 24 hours after surgery, the PONV score of group B/C/D was significantly lower than that of group A (P < 0.01). No significant difference was observed in the general data and visual analogue scores for postoperative pain between the 4 groups.

CONCLUSION

Naloxone admixture administered at 0.4 to 0.6 μg·kg-1·h-1 can exert an effective inhibitory effect on the incidence and intensity of PONV in gynecological laparoscopic surgery.

Neuraxial labor analgesia: Initiation techniques

The ideal technique for labor analgesia would have a quick onset, predictable quality, and adjustable depth and duration. Moreover, it would be easy to perform and have minimal maternal and fetal side effects. A catheter-based neuraxial approach encompasses these desirable characteristics and includes the epidural, combined spinal epidural, dural puncture epidural, and intrathecal catheter techniques. In this review, we outline the unique technical considerations, analgesic characteristics, and side effect profiles for each technique that can ultimately impact the maternal-fetal dyad. The selection of neuraxial analgesia techniques should consider the patient and team's goals and expectations, the clinical context, and the institutional culture. Labor analgesic techniques that initiate with an intentional dural puncture component have a faster onset, greater bilateral and sacral spread, and lower rates of epidural catheter failure. Further elucidation of the mechanisms, benefits, and risks of each neuraxial initiation technique will continue to benefit patients and care providers.

The use of topical nalbuphine in different concentrations to control pain after photorefractive keratectomy

PURPOSE

This is a randomized controlled study aiming to evaluate the safety and efficacy of two different concentrations of topical nalbuphine hydrochloride, when used to relieve pain in the first days following photorefractive keratectomy (PRK).

METHODS

This is a prospective double blinded randomized clinical trial that included 189 patients who had PRK for correction of low and moderate refractive errors. Patients were randomly assigned to three groups according to the eye drops given to relieve pain in the first three postoperative days; the first group received topical nalbuphine with a concentration of 2 mg/ml (Group A = 64 patients), the second group received topical nalbuphine in a concentration of 1 mg/ml (Group B = 69 patients) and the third group received topical artificial tears only (Group C = 56 patients).The patients were asked to rate their pain daily using a numeric rating scale and to record the number of drops instillation times/day. The time needed for complete epithelial healing, best-corrected visual acuity (BCVA) and spherical equivalent after three months were recorded in each group.

RESULTS

In the first three days, there was a statistically significant difference in pain score among the three groups with lower values in the two topical nalbuphine groups when compared with the control group receiving artificial tears. Moreover, the higher concentration group showed significantly lower pain score and less number of drops used /day in comparison with the lower concentration group.There were no statistically significant differences in epithelial healing time, BCVA and spherical equivalent after three months among the three groups.

CONCLUSION

The use of topical nalbuphine is effective in relieving pain in the first few days following PRK and this pain relief is not associated with any compromise regarding epithelial healing nor refractive outcome. The pain control with 2 mg/ml concentration is significantly higher than that with 1 mg/ml concentration of nalbuphine. Trial registration numberISRCTN21394752 https://doi.org/10.1186/ISRCTN21394752 The trial is retrospectively registered in ISRCTN registry at March 08, 2021.

MRGPRX2 and Adverse Drug Reactions

Many adverse reactions to therapeutic drugs appear to be allergic in nature, and are thought to be triggered by patient-specific Immunoglobulin E (IgE) antibodies that recognize the drug molecules and form complexes with them that activate mast cells. However, in recent years another mechanism has been proposed, in which some drugs closely associated with allergic-type events can bypass the antibody-mediated pathway and trigger mast cell degranulation directly by activating a mast cell-specific receptor called Mas-related G protein-coupled receptor X2 (MRGPRX2). This would result in symptoms similar to IgE-mediated events, but would not require immune priming. This review will cover the frequency, severity, and dose-responsiveness of allergic-type events for several drugs shown to have MRGPRX2 agonist activity. Surprisingly, the analysis shows that mild-to-moderate events are far more common than currently appreciated. A comparison with plasma drug levels suggests that MRGPRX2 mediates many of these mild-to-moderate events. For some of these drugs, then, MRGPRX2 activation may be considered a regular and predictable feature after administration of high doses.

Evaluation of Therapies for Peripheral and Neuraxial Opioid-induced Pruritus based on Molecular and Cellular Discoveries

Opioids are a mainstay of treatment for pain worldwide. Pruritus, a common side effect of opioids, is a patient dissatisfier that limits their use in many clinical settings. Both parenteral and neuraxial administration of opioids frequently evoke pruritus. The ability of opioids to suppress pain while causing itch continues to perplex clinicians and researchers alike. Several mechanisms have been proposed to explain how opioids can give rise to pruritus, but specific knowledge gaps perpetuate debate. This review summarizes the clinical burden of opioid-induced pruritus and emphasizes recent discoveries of peripheral and central mechanisms for opioid-induced pruritus, particularly with respect to scientific and conceptual advances in spinal cord circuitry and mast cell biology. The mechanisms and effectiveness of existing medications used for clinical management of pruritus will be evaluated, and we will highlight the emerging preclinical utility of selective κ-opioid receptor agonists, such as nalfurafine, for the management of opioid-induced pruritus.

A comparative study of three concentrations of intravenous nalbuphine combined with hydromorphone for post-cesarean delivery analgesia

Background:

Nalbuphine has been suggested to be used for post-cesarean section (CS) intravenous analgesia. However, ideal concentration of nalbuphine for such analgesia remains unclear. The present study was conducted to explore an ideal concentration of nalbuphine for post-CS intravenous analgesia by evaluating the analgesic effects and side-effects of three different concentrations of nalbuphine combined with hydromorphone for post-CS intravenous analgesia in healthy parturients.

Methods:

One-hundred-and-fourteen parturients undergoing elective CS were randomly allocated to one of three groups (38 subjects per group) according to an Excel-generated random number sheet to receive hydromorphone 0.05 mg/mL + nalbuphine 0.5 mg/mL (group LN), hydromorphone 0.05 mg/mL + nalbuphine 0.7 mg/mL (group MN), and hydromorphone 0.05 mg/mL + nalbuphine 0.9 mg/mL (group HN) using patient-controlled analgesia (PCA) pump. Visual analog scale (VAS) for pain, PCA bolus demands, cumulative PCA dose, satisfaction score, Ramsay score, and side-effects such as urinary retention were recorded.

Results:

The number of PCA bolus demands and cumulative PCA dose during the first 48 h after CS were significantly higher in group LN (21 ± 16 bolus, 129 ± 25 mL) than those in group MN (15 ± 10 bolus, 120 ± 16 mL) (both P < 0.05) and group HN (13 ± 9 bolus, 117 ± 13 mL) (both P < 0.01), but no difference was found between group HN and group MN (both P > 0.05). VAS scores were significantly lower in group HN than those in group MN and group LN for uterine cramping pain at rest and after breast-feeding within 12 h after CS (all P < 0.01) and VAS scores were significantly higher in group LN than those in group MN and group HN when oxytocin was intravenously infused within 3 days after CS (all P < 0.05), whereas VAS scores were not statistically different among groups for incisional pain (all P > 0.05). Ramsay sedation scale score in group HN was significantly higher than that in group MN at 8 and 12 h after CS (all P < 0.01) and group LN at 4, 8, 12, 24 h after CS (all P < 0.05).

Conclusions:

Hydromorphone 0.05 mg/mL + nalbuphine 0.7 mg/mL for intravenous PCA could effectively improve the incisional pain and uterine cramping pain management and improve comfort in patients after CS.

Trial registration number:

ChiCTR1800015014, http://www.chictr.org.cn/ Chinese Clinical Trial Registry.

Naloxone Continuous Infusion for Spinal Cord Protection in Endovascular Aortic Surgery Leads to Higher Opioid Administration and More Pain

OBJECTIVE

Compare total perioperative opioid use in patients receiving naloxone continuousinfusion (NCI) for spinal cord ischemia prophylaxis, versus patients not receiving NCI, in endovascular aortic repair.

DESIGN

Single-center, retrospective cohort review.

SETTING

Academic medical center.

PARTICIPANTS

Patients undergoing elective thoracic, thoracoabdominal, or abdominal aortic endovascular repair.

INTERVENTIONS

Patients were separated based on the use of naloxone continuous infusion as part of a spinal protection protocol. Primary endpoint was opioid requirements, in milligram morphine equivalents (MME), during the first 48 hours or during NCI. Secondary endpoints included: postoperative pain scores during the same interval; opioid requirements during hours 48 to 72; and pain scores during hours 48 to 72.

MEASUREMENTS AND MAIN RESULTS

Ninety-five procedures were included; 43 received naloxone continuous infusion and 52 patients were in the non-naloxone group. Opioid use from a linear mixed model was elevated across the entire continuum in the naloxone group (18 MMEs, 95% CI 13-24), with the greatest difference seen at the 24-to-48-hour interval (51 MMEs, 95% CI 26-75) after adjustment for age, incisions, and prehospital opioid use. In the naloxone group, pain score estimates were elevated at each postoperative interval of evaluation, with similar adjustment. Across the continuum this was 0.7 higher (95% CI 0.2-1.3); the zero-six-hour and six-to-12-hour intervals were 0.9 (95% CI 0.4-1.4) and 1.2 higher (95% CI 0.7-1.7).

CONCLUSIONS

Patients receiving anloxone continuous infusion to prevent spinal cord ischemia required greater quantities of opioids and had higher postoperative pain, compared with patients not requiring naloxone.

Itching as the onset of pain (part 3)

Itchy skin is an extremely unpleasant symptom that can provoke insomnia, depression, irritability, loss of appetite. There are several theories of itching. According to one of them, itching is a modified pain caused by a slight irritation of the nerve endings in the skin. According to the second, itching is an independent symptom, in the formation of which nervous, humoral and vascular mechanisms are involved. Other theories consider itching as a reaction of the autonomic nervous system or a hereditary pathological condition. According to recent studies, itchy skin is characterized by the absence of a universal peripheral mediator of itching. The trigger for itching is the action of pruritogen – a mechanical, chemical, thermal or electrical stimulant directly or indirectly through mediators. Free ends of type A delta fibers and type C fibers play a crucial role in itching and pain. If this was previously confirmed only by clinical observations, now there are neurophysiological studies that support the theory that itching and pain fibers are one with different activity thresholds. Today, it is unacceptable that there are separate specific receptors for different sensations. It is now assumed that there are mixed receptors for heat, cold, pain, itching and touch [95]. Systematic use of substances included in the list of drugs and manifested by mental and physical dependence on them – drug addiction, one of the diseases of society. But drug addiction is sometimes forced, according to medical indications, in cases of palliative conditions. Depending on the stage of the person after taking the drug or in the interval between drug use, one of the signs of use may be severe itching of the skin. And after excluding both the main diseases that cause itching and other secondary causes of itching, it can be assumed that a person has idiopathic generalized pruritus (itching) of unknown origin (GPOU). The itching of the elderly, which is quite common in the elderly, as a manifestation of concomitant, often combined, somatic pathology, but may also be due to physiological changes, both on the skin and on the physiological aging of nerve endings.

Strategies of analgesic treatment after cesarean delivery. Current state and new alternatives

The number of caesarean sections performed worldwide is increasing, and with it, the need for the optimal analgesia strategies. Deficient postoperative analgesia increases the need for opioids, delays recovery, and is associated with chronic pain and postpartum depression. It is essential to find good postoperative pain control strategies that facilitate early mobility, early recovery, and early hospital discharge with minimal side effects on the mother and infant. Multimodal analgesia based on neuroaxial anaesthesia with morphine in combination with non-opioids such as non-steroidal anti-inflammatory drugs and paracetamol, gives the best post-caesarean analgesia outcome, and allows anaesthesiologists to reserve opioids, corticoids, gabapentin, magnesium or ketamine for situations where neuroaxial anaesthesia cannot be performed, for high-risk patients, or when pain is difficult to control. Peripheral nerve block techniques can also be added, such as transverse abdominis plane block, erector spinae block, or continuous wound infiltration.

Nalbuphine Reduces Opioid-Associated Urinary Retention in Pediatric Patients

OBJECTIVES

To evaluate the effect of nalbuphine administration on urine output in critically ill children with opioid-associated urinary retention.

DESIGN

Institutional review board approved, single center, retrospective medical chart review.

SETTING

Large medical-surgical PICU within a free-standing, tertiary care children's hospital.

PATIENTS

Patients admitted to the PICU between October 1, 2014, and February 29, 2016, who received IV nalbuphine after meeting criteria for opioid-associated oliguria (defined as urine output below 1 mL/kg/hr and received at least one dose of opioid therapy within the preceding 12 hr).

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Seventeen patients who received 21 doses of nalbuphine were analyzed. The median age and weight of patients were 6 years (interquartile range, 3-11.5 yr) and 18 kg (interquartile range, 12-35 kg), respectively. Two distinct dosing strategies became evident, specifically 0.05 mg/kg (n = 11 doses) and 0.1 mg/kg (n = 10 doses). Urine output increased significantly from baseline (median, 0 mL/kg/hr; interquartile range, 0-0.53 mL/kg/hr) to 6 hours post nalbuphine administration (median, 1.48 mL/kg/hr; interquartile range, 0-2 mL/kg/hr; p = 0.0002). Patients who received 0.1 mg/kg/dose had a greater urine output response compared with those who received 0.05 mg/kg/dose. Five patients (29%) had a catheter inserted into their bladder after administration of nalbuphine. Pain scores (grouped 6 hr before and after nalbuphine administration and single pain scores documented immediately before and after nalbuphine administration) were unchanged.

CONCLUSIONS

Nalbuphine administration, at a dose of 0.1 mg/kg, improved urine output in a cohort of children with opioid-associated urinary retention. Pain control did not appear influenced by the provision of nalbuphine. Additional studies are needed to determine the influence of nalbuphine on urinary catheter insertion rates and catheter-associated urinary tract infections.

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.

The application of nalbuphine in patient-controlled intravenous analgesia for patients undergoing subtotal gastrectomy

The aim of the present study was to investigate the analgesic effect and safety of the application of different doses of nalbuphine in patient-controlled intravenous analgesia (PCIA) for patients undergoing subtotal gastrectomy. A total of 120 patients, who underwent subtotal gastrectomy at our hospital between May, 2015 and January, 2017 under combined spinal epidural combined anesthesia, were selected. The patients received PCIA after surgery. The patients were randomly divided into four groups, including the morphine (MOP group), nalbuphine 60 mg (N60 group), nalbuphine 80 mg (N80 group) and nalbuphine 100 mg (N100 group). The first dose of PCIA treatment was 2 ml, the background dose was 2 ml/h, PCIA dose was 0.5 ml, and the lockout time was 15 min. Postoperative vital signs and adverse reactions (bleeding, fullness and aching of upper abdomen and vomiting) were recorded. The visual analogue scale (VAS) and Ramsay sedation score of patients were evaluated. The number of PCIA and analgesia-related complications during analgesia were recorded. No significant differences in general data were found among the four groups (P>0.05). The VAS score of the three nalbuphine groups was lower than that of the MOP group, but the differences were not significant. All postoperative Ramsay sedation scores of the four groups showed appropriate sedation, but no significant differences were found between the groups. Compared with the MOP group, the use of postoperative PCIA was significantly delayed and the number of PCIA was significantly smaller in the three nalbuphine groups (P<0.05). The results show that the analgesic effect and safety of the use of PCIA for patients undergoing subtotal gastrectomy were satisfactory.

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.

Harms associated with taking nalmefene for substance use and impulse control disorders: A systematic review and meta-analysis of randomised controlled trials

Importance

Nalmefene is a newly approved drug for alcohol use disorder, but the risk of harms has not been evaluated from empirical trial evidence.

Objective

To assess the harm of nalmefene administered to individuals diagnosed with substance use or impulse control disorders by performing a systematic review and meta-analysis of randomised controlled trials.

Data sources

A search was performed in Cochrane Central Register of Controlled Trials (CENTRAL, 2014), MEDLINE via PubMed (1950), EMBASE via Ovid (1974), and Clinicaltrials.gov through December 2014.

Study selection

This study included only randomised controlled trials with placebo or active controls that administered nalmefene to adult individuals for treating impulse control and/or substance use disorders. Both published and unpublished randomised controlled trials were eligible for inclusion.

Data extraction and synthesis

Internal validity was assessed using the Cochrane risk-of-bias tool. Published information from the trials was supplemented by contact between reviewers and industry sponsor. Data were combined using two meta-approaches in fixed effects models; Peto Odds Ratios and risk differences were reported with 95% confidence intervals (95%CIs).

Main outcomes and measures

Number of patients with serious adverse events, including specific psychiatric serious adverse events and withdrawals due to adverse events.

Results

Of 20 potentially relevant studies, 15 randomised controlled trials met the inclusion criteria, and 8 of these provided data enabling the meta-analysis. Overall, serious adverse events did not occur more often in the nalmefene group than in the placebo group (Peto Odds Ratio = 0.97 [95% CI 0.64–1.44]; P = 0.86). Risk of psychiatric serious adverse events was slightly elevated, albeit not at a statistically significant level (Peto Odds Ratio = 1.32 [95% CI 0.62, 2.83]; P = 0.47). Withdrawals due to adverse events were significantly more likely to occur with nalmefene compared to placebo (Peto Odds Ratio = 3.22 [95% CI 2.46–4.22]; P<0.001)

Conclusions and relevance

The three-fold increased risk of withdrawal from treatment on nalmefene due to adverse events is a matter of safety concern. The nature of these adverse events cannot be elucidated further without access to individual patients data.

Comparison of intrathecal morphine and surgical-site infusion of ropivacaine as adjuncts to intravenous patient-controlled analgesia in living-donor kidney transplant recipients

INTRODUCTION

This prospective observational study compared the postoperative analgesic effectiveness of intrathecal morphine (ITM) and surgical-site infusion (SSI) of ropivacaine as adjuncts to intravenous (IV) patient-controlled analgesia (PCA) (fentanyl) in living-donor kidney transplant recipients.

METHODS

Patients undergoing living-donor kidney transplantation who received ITM or SSI in addition to IV PCA were included. Rescue analgesia was achieved with IV meperidine as required. The primary outcome, measured using the Numeric Pain Rating Scale (NRS), was pain at rest and when coughing. Patients were assessed for 48 hours after surgery.

RESULTS

A total of 53 patients (32 ITM, 21 SSI) were included in the study. The ITM group showed significantly lower NRS scores, at rest and when coughing, for up to 12 and eight hours. NRS scores were comparable between the groups at other times. The ITM group had significantly less postoperative systemic opioid requirement in the first 24 hours, but there was no significant difference between the systemic opioid consumption of the groups on postoperative Day 2. In the ITM group, 3 (9.4%) patients presented with bradypnoea and 1 (3.1%) with excessive sedation in the first 12 postoperative hours. More patients in the ITM group developed pruritus requiring treatment during the first 24 hours. There were no differences between the groups in other outcomes (e.g. nausea/vomiting, change in pulmonary or kidney functions).

CONCLUSION

Compared with SSI, ITM reduced immediate postoperative pain and IV opioid consumption on postoperative Day 1 after living-donor kidney transplantation, but at the cost of increased pruritus and respiratory depression.

Optimal Pain Management After Cesarean Delivery

Cesarean delivery rates are increasing worldwide, and effective postoperative pain management is a key priority of women undergoing cesarean delivery. Inadequate pain management in the acute postoperative period is associated with persistent pain, greater opioid use, delayed functional recovery, and increased postpartum depression. In addition to pain relief, optimal management of patients after cesarean delivery should address the goals of unrestricted maternal mobility, minimal maternal and neonatal side effects, rapid recovery to baseline functionality, and early discharge home. Multimodal analgesia should include neuraxial morphine in conjunction with nonopioid adjuncts, with additional oral or intravenous opioids reserved for severe breakthrough pain.

The effect of naloxone treatment on opioid-induced side effects: A meta-analysis of randomized and controlled trails

BACKGROUND

To evaluate the effects of naloxone on opioid-induced side effects, the present meta-analysis was constructed.

METHODS

Electronic databases including PubMed, EMBASE, and CNKI (China National Knowledge Internet) were used for literature search. Studies on comparison of opioid-side effects between naloxone-treated group and placebo or normal saline-related group were included in the meta-analysis. Heterogeneity analysis was performed with Chi-square and I test. Pooled analysis was based on fixed-effects model, if heterogeneity between the eligible studies was negligible (I < 50%, P > 0.05), otherwise, random-effects model was used. Sensitivity analysis was applied to assess the robustness of the results and publication bias was evaluated by Begg and Egger test.

RESULTS

Thirteen studies including 1138 patients were included in the meta-analysis. Pooled analysis indicated that naloxone could significantly reduce the occurrence of pruritus (RR [risk ratio] = 0.252, 95% CI [confidence interval] = 0.137-0.464), nausea (RR = 0.323, 95% CI = 0.245-0.428), and vomiting (RR = 0.338, 95% CI = 0.192-0.593) which were induced by opioids. However, naloxone did not relieve pain (standardized mean difference [SMD] = -0.052, 95% CI = -0.453 to 0.348) and somnolence (RR = 0.561, 95% CI = 0.287 to 1.097) in patients received opioid treatment. Additionally, there were no significant publication bias between the included studies (Begg test, P = 0.602; Egger test, P = 0.388).

CONCLUSION

Addition of naloxone might act as an effective treatment for prophylaxis of opioid-induced pruritus, nausea, and vomiting in clinical practice.

Intravenous nalbuphine 50 µg·kg(-1) is ineffective for opioid-induced pruritus in pediatrics

PURPOSE

This investigation evaluated the efficacy of nalbuphine in treating postoperative opioid-induced pruritus (Pr) in pediatric patients.

METHODS

After Ethics Board approval, the dual site, tertiary care teaching centre study recruited 212 subjects, age ≥ seven years, who received opioid analgesia postoperatively. A modified, self-report colour analogue scale (CAS) scored pruritus intensity (PrI). Subjects who reported PrI score ≥ 5/10 were randomized to treatment with nalbuphine 50 µg·kg(-1) iv (max 5 mg) or saline placebo. A pruritus intensity difference (PrID) ≥ 50% was considered a positive outcome.

RESULTS

Of 260 subjects approached, 212 consented and 184 received opioids. Median age was 13 yr (range 7-19) and median weight was 51 kg (range 19.6-134.8 kg). Pruritus intensity ≥ 5/10 occurred in 37 (20.1%) subjects. Intravenous morphine [patient-controlled analgesia (PCA)/continuous infusion] was associated with Pr in 68% of subjects over a wide dose range (9.4-63.2 µg·kg(-1)·hr(-1)). Pruritis occurred in 36% of patients in the PCA group compared to continuous opioid infusion (27%) and epidural administration (27%). Pruritus intensity difference ≥ 50% was achieved in 55.6% of nalbuphine and 57.9% of saline-treated subjects.

CONCLUSION

This preliminary report suggests that nalbuphine 50 µg·kg(-1) iv is not effective in treating postoperative opioidinduced pruritus in pediatric patients. The modified CAS score and PrID warrant further investigation.

OBJECTIF

Évaluer l'efficacité de la nalbuphine contre le prurit (Pr) postopératoire induit par les opioïdes chez des patients pédiatriques. MéTHODE: Nous avons recruté 212 sujets de ≥ sept ans qui ont reçu une analgésie opioïde postopératoire. Une échelle analogique de couleur (EAC) modifiée pour l'auto-évaluation a mesuré les scores d'intensité du prurit (IPr). Répartis au hasard, les sujets dont les scores d'IPr étaient ≥ 5/10 ont reçu de la nalbuphine à 50 µg·kg(-1) iv (5 mg maximal) ou un placebo salin. Une différence d'intensité de prurit (DIPr) ≥50% était considérée positive. RéSULTATS: Des 260 sujets rencontrés, 212 ont participé à l'étude et 184 ont reçu des opioïdes. L'âge moyen a été de 13 ans (7-19) et le poids moyen de 51 kg (19,6-134,8 kg). Un prurit ≥ 5/10 a été noté chez 37 (20,1 %) des sujets. De la morphine intraveineuse [en analgésie auto-contrôlée (AAC) ou en perfusion continue] a été associée à du Pr chez 68 % des sujets pour un grand éventail de doses (9,4-63,2 µg·kg(-1)·h(-1)). Le prurit s'est manifesté chez 36 % des patients avec l'AAC comparée à la perfusion d'opioïde continue (27 %) et à l'administration péridurale (27 %). Une différence d'intensité du prurit ≥ 50 % a été atteinte chez 55,6 % des sujets qui recevaient la nalbuphine et 57,9 % de ceux qui avaient le placebo.

CONCLUSION

La nalbuphine iv à 50 µg·kg(-1) n'est pas efficace pour traiter le prurit postopératoire induit par les opioïdes chez des patients pédiatriques. Le score modifié à l'EAC et la DIPr devront être étudiés plus à fond.

Comparison of droperidol and ondansetron prophylactic effect on subarachnoid morphine-induced pruritus

BACKGROUND AND OBJECTIVES

The prophylactic effect of ondansetron on subarachnoid morphine-induced pruritus is controversial, while evidence suggests that droperidol prevents pruritus. The aim of this study is to compare the effects of droperidol and ondansetron on subarachnoid morphine-induced pruritus.

METHODS

180 ASA I or II patients scheduled to undergo cesarean sections under subarachnoid anesthesia combined with morphine 0.2mg were randomized to receive, after the child's birth, metoclopramide 10mg (Group I - control), droperidol 2.5mg (Group II) or ondansetron 8mg (Group III). Postoperatively, the patients were assessed for pruritus (absent, mild, moderate or severe) or other side effects by blinded investigators. Patients were also blinded to their group allocation. The tendency to present more severe forms of pruritus was compared between groups. NNT was also determined.

RESULTS

Patients assigned to receive droperidol [Proportional odds ratio: 0.45 (95% confidence interval 0.23-0.88)] reported less pruritus than those who received metoclopramide. Ondansetron effect was similar to metoclopramide [Proportional odds ratio: 0.95 (95% confidence interval 0.49-1.83)]. The NNT for droperidol and ondansetron was 4.0 and 14.7, respectively.

CONCLUSIONS

Ondansetron does not inhibit subarachnoid morphine-induced pruritus.

Association of lipophilic opioids and hyperbaric bupivacaine in spinal anesthesia for elective cesarean section. Randomized controlled study

PURPOSE

To evaluate the efficacy and side-effects of fentanyl and sufentanil combined with hyperbaric spinal bupivacaine in elective cesarean section.

METHODS

A prospective, randomized, double-blind study with 64 term parturients, distributed into 2 groups according to the opioid combined with hyperbaric bupivacaine 0.5% (10mg): GF - fentanyl (25 µg) and GS - sufentanil (5.0 µg). The latency and maximum sensory block level; degree and duration of motor block; duration and quality of analgesia; maternal-fetal repercussions were evaluated. This was an intention-to-treat analysis with a 5% significance level.

RESULTS

The latency period, maximum sensory block level, motor block degree and perioperative analgesia were similar in both groups. Motor block and analgesia had a longer duration in the sufentanil group. Maternal adverse effects and neonatal repercussions were similar. The incidence of hypotension was higher in the fentanyl group. In both groups, there was a predominance of patients who were awake and either calm or sleepy.

CONCLUSIONS

The addition of fentanyl and sufentanil to hyperbaric subarachnoid bupivacaine was shown to be effective for the performance of cesarean section, and safe for the mother and fetus. Analgesia was more prolonged with sufentanil.

A comparision of nalbuphine with morphine for analgesic effects and safety : meta-analysis of randomized controlled trials

Although morphine is the standard opioid analgesic for pain control and has been widely used, certain drug-induced adverse effects have been reported as intolerable and need to be addressed. Nalbuphine may have a few advantages over morphine in this respect. We aimed to describe the effect of nalbuphine as well as its saftey compared to morphine by analyzing published randomized controlled trials (RCTs) with meta-analysis approach. We analysed 15 trials (820 patients). Overall, there was no evidence to show that the effect of pain relief had any difference between nalbuphine and morphine (pooled relative risks [RRs], 1.01; 95% CI, 0.91 to 1.11; P = 0.90). On the other hand, the incidences of pruritus, nausea, vomiting, respiratory depression were significantly lower in nalbuphine group compared with morphine group, and the pooled RRs were 0.78(95%CI, 0.602–0.997; P = 0.048) for nausea, 0.65(95%CI, 0.50–0.85; P = 0.001) for vomiting, 0.17(95%CI, 0.09–0.34; P < 0.0001) for pruritus, and 0.27(95%CI, 0.12–0.57; P = 0.0007) for respiratory depression. The analgesic efficacy of nalbuphine is comparable to morphine, but nalbuphine provides a better safety profile than morphine in the aspect of certain side-effects, especially related to pruritus and respiratory depression.

A naloxone admixture to prevent opioid-induced pruritus in children: a randomized controlled trial

PURPOSE

Morphine administered by continuous opioid infusion (COI) or by patient-controlled analgesia (PCA) is associated with opioid-induced pruritus (OIP). Intravenous naloxone administered separately to the morphine infusion at a dose of 0.25-1.65 μg·kg(-1)·hr(-1) can provide effective prevention from OIP. Nevertheless, this strategy requires a dedicated intravenous line and an additional infusion pump. The purpose of this study was to determine whether an admixture of naloxone with morphine in normal saline administered via COI or PCA would also prevent OIP in children without attenuation of analgesia or increased opioid utilization.

METHODS

In this randomized controlled trial, children meeting the inclusion criteria (aged 8-18 yr, American Society of Anesthesiologists physical status I-III, normal developmental profile and prescribed COI/PCA morphine for postoperative analgesia) were randomized to receive an infusion containing a naloxone, opioid, and saline admixture (NOSA) of 12 μg naloxone per 1 mg morphine per 1 mL normal saline or morphine only (control). The severity of opioid-induced pruritus was assessed by self-report using a modified colour analogue scale (mCAS; score 0-10). The groups were also compared for opioid utilization, pain scores, and administration of antipruritic medications, which were recorded for up to 48 hr or until the COI/PCA was discontinued.

RESULTS

Ninety-two participants were enrolled in the study. The median [interquartile range] dose of naloxone administered to the NOSA participants was 0.37 [0.30-0.48] μg·kg(-1)·hr(-1). The incidence of OIP, determined by self-report and treatment, was not different between groups: 22% in the NOSA group vs 36% in the control group (mean difference, -15%; 95% confidence interval [CI], -33 to 4; P = 0.164). The severity of opioid-induced pruritus was similar in the two groups, with a median difference in the participants' mean mCAS score of -0.29 (95% CI, -0.75 to 0.26; P = 0.509). Opioid utilization did not differ between groups, with a median difference of -1.35 μg·kg(-1)·hr(-1) (95% CI, -5.85 to 7.55; P = 0.518), and pain scores did not differ, with a median difference of 0.0 (95% CI, -1.0 to 1.5; P = 0.659).

CONCLUSION

This admixture of naloxone and morphine in normal saline did not decrease the incidence or severity of OIP in this sample. Separate administration of naloxone may be the more effective strategy for prevention of OIP. This trial was registered at ClinicalTrials.gov (NCT01071057).

[Comparison of droperidol and ondansetron prophylactic effect on subarachnoid morphine-induced pruritus]

BACKGROUND AND OBJECTIVES

The prophylactic effect of ondansetron on subarachnoid morphine-induced pruritus is controversial, while evidence suggests that droperidol prevents pruritus. The aim of this study is to compare the effects of droperidol and ondansetron on subarachnoid morphine-induced pruritus.

METHODS

180 ASA I or II patients scheduled to undergo cesarean sections under subarachnoid anesthesia combined with morphine 0.2mg were randomized to receive, after the child's birth, metoclopramide 10mg (Group I - control), droperidol 2.5mg (Group II) or ondansetron 8mg (Group III). Postoperatively, the patients were assessed for pruritus (absent, mild, moderate or severe) or other side effects by blinded investigators. Patients were also blinded to their group allocation. The tendency to present more severe forms of pruritus was compared between groups. NNT was also determined.

RESULTS

Patients assigned to receive droperidol [Proportional odds ratio: 0.45 (95% confidence interval 0.23-0.88)] reported less pruritus than those who received metoclopramide. Ondansetron effect was similar to metoclopramide [Proportional odds ratio: 0.95 (95% confidence interval 0.49-1.83)]. The NNT for droperidol and ondansetron was 4.0 and 14.7, respectively.

CONCLUSIONS

Ondansetron does not inhibit subarachnoid morphine-induced pruritus.

Prophylactic administration of ondansetron in prevention of intrathecal morphine-induced pruritus and post-operative nausea and vomiting in patients undergoing caesarean section

Background

Intrathecal morphine is commonly used for post caesarean analgesia. However, their use is frequently associated with the incidence of troublesome side effects such as nausea, vomiting and pruritus. Various mechanisms have been postulated for the opioid-induced pruritus, with a variety of medications with different mechanisms of actions formulated for the prevention and treatment. But, the results are inconsistent and hence the prevention and treatment of opioid-induced pruritus still remains a challenge. Ondansetron which is antiemetic, non-sedative and has no antianalgesic effect is an antagonist to 5-HT3 receptor, the receptor with which opioids interacts and imparts its effects. Ondansetron, thus, would be an attractive treatment strategy for both opioid-induced pruritus and post-operative nausea and vomiting.

Methods

After the approval from institutional review committee and written consent received from the patient, 50 healthy parturients of ASA I and II physical status undergoing caesarean section under spinal anaesthesia were enrolled for the study. They were randomly categorized into placebo group (2 ml normal saline) and treatment group (2 ml of 4 mg ondansetron), each group containing 25 patients. Pruritus and post-operative nausea and vomiting scores were recorded up to 24 hours after the administration of intrathecal morphine. Statistical analysis was performed using chi-square test.

Results

The incidence, severity and necessity of treatment for pruritus in the treatment group was significantly reduced compared to the placebo group (16% vs 88%). Similarly, the risk of post-operative nausea and vomiting in the treatment group was less compared to the placebo group (8% vs 56%).

Conclusion

Prophylactic administration of ondansetron to parturients receiving intrathecal morphine for post-operative analgesia provides a significant reduction of intrathecal morphine-induced pruritus and nausea and vomiting.

Trial registration

CTRI/2015/01/005362 registered on 07/01/2015 in Clinical Trials Registry – India (ctri.nic.in).

Anesthetic premedication: new horizons of an old practice

The practice of anesthetic premedication embarked upon soon after ether and chloroform were introduced as general anesthetics in the middle of the 19(th) century. By applying opioids and anticholinergics before surgery, the surgical patients could achieve a less anxious state, and more importantly, they would acquire a smoother course during the tedious and dangerous induction stage. Premedication with opioids and anticholinergics was not a routine practice in the 20(th) century when intravenous anesthetics were primarily used as induction agents that significantly shorten the induction time. The current practice of anesthetic premedication has evolved into a generalized scheme that incorporates several aspects of patient care: decreasing preoperative anxiety, dampening intraoperative noxious stimulus and its associated neuroendocrinological changes, and minimizing postoperative adverse effects of anesthesia and surgery. Rational use of premedication in modern anesthesia practice should be justified by individual needs, the types of surgery, and the anesthetic agents and techniques used. In this article, we will provide our readers with updated information about premedication of surgical patients with a focus on the recent application of second generation serotonin type 3 antagonist, antidepressants, and anticonvulsants.

Nalbuphine-induced psychosis treated with naloxone

PURPOSE

A case of nalbuphine-induced psychosis, which resolved after the administration of naloxone, is described.

SUMMARY

A 25-year-old African-American woman with a history of systemic lupus erythematosus was admitted to the hospital for management of cholecystitis. A laparoscopic cholecystectomy was performed, and the patient received multiple doses of i.v. hydromorphone for postoperative pain management. Four days later, shortly after receiving a dose of i.v. nalbuphine for opioid-induced pruritus, she experienced an acute psychotic event, with symptoms including intense headache, akathisia, altered mental status, and formication (a hallucinatory sensation of insects crawling on the skin). The neuropsychiatric symptoms abated within 5 minutes of two consecutively administered doses of i.v. naloxone. During this event, which lasted 25-30 minutes, there was no evidence of metabolic abnormalities and were no signs of infection. The patient did not have a history of mental illness or substance abuse. The patient did not receive further doses of nalbuphine and did not experience similar events during her hospital stay; she was discharged home 10 days later without further complications. According to the algorithm of Naranjo et al., the case was assigned a score of 6, indicating a probable adverse reaction to nalbuphine.

CONCLUSION

A patient developed an acute psychotic reaction that was probably secondary to administration of i.v. nalbuphine for opioid-induced pruritus. Evidence supporting this diagnosis included correlation between the timing of administration of nalbuphine and symptom onset and the marked improvement in mentation following the administration of naloxone.

Prophylaxis and treatment of the side-effects of neuraxial morphine analgesia following cesarean delivery

PURPOSE OF REVIEW

Neuraxial morphine is commonly used for analgesia after cesarean delivery, but is frequently associated with postoperative nausea and vomiting (PONV) and pruritus. This review describes the recent advances in the management of those side-effects.

RECENT FINDINGS

Neuraxial-morphine-induced side-effects are dose related; therefore, the minimum effective dose should be used. Dexamethasone, 5HT3 receptor antagonists, antihistamines, and anticholinergics reduce the incidence of PONV, whereas metoclopramide 10 mg does not appear to be effective for PONV prophylaxis in this patient population. Combination antiemetic therapy provides improved prophylaxis compared with monotherapy, but has seldom been studied in women undergoing cesarean delivery with neuraxial morphine. Studies of P6 acupressure reported inconsistent results. Polymorphism of the μ-opioid receptor may affect the severity of neuraxial-morphine-induced pruritus. Opioid antagonists and mixed agonist/antagonists appear to be the most useful for the management of opioid-induced pruritus. Prophylactic 5HT3 receptor antagonists and dexamethasone do not seem to be effective for reducing the incidence of pruritus. In contrast, ondansetron, pentazocine, and dimenhydrinate may be useful for treating established pruritus.

SUMMARY

PONV and pruritus are frequent side-effects of neuraxial morphine. Future studies investigating combination antiemetic therapy, long-acting antiemetics, and strategies to manage pruritus are needed.

Comparison of clinical effects according to the dosage of sufentanil added to 0.5% hyperbaric bupivacaine for spinal anesthesia in patients undergoing cesarean section

Background

Subarachnoid block is a widely used technique for cesarean section. To improve the quality of analgesia and prolong the duration of analgesia, addition of intrathecal opioids to local anesthetics has been encouraged. We compared the effects of sufentanil 2.5 µg and 5 µg, which were added to intrathecal hyperbaric bupivacaine.

Methods

We enrolled 105 full term parturients were randomly divided into 3 groups: Group 1 (control), Group 2 (sufentanil 2.5 µg), and Group 3 (sufentanil 5 µg). In every group, 0.5% heavy bupivacaine was added according to the adjusted dose regimen. We determined the maximum level of sensory block and motor block, the quality of intraoperative analgesia, the duration of effective analgesia and side effects.

Results

There were no significant differences among the 3 groups in the maximum level of the sensory block and motor block. Recovery rate of the sensory block, however, was significantly slower in Group 3 than Group 1. Quality of intraopertive analgesia, muscle relaxation, and duration of effective analgesia were enhanced by increasing the dosage of intrathecal sufentanil. Frequencies of hypotension, maximum sedation level, and pruritus were directly related to the dosage of intrathecal sufentanil, whereas nausea and vomiting occurred only in the groups using sufentanil.

Conclusions

The addition of sufentanil 2.5 µg for spinal anesthesia provides adequate intraoperative analgesia and good postoperative analgesia with minimal adverse effects on the mother.

Comparison of fentanyl and sufentanil added to 0.5% hyperbaric bupivacaine for spinal anesthesia in patients undergoing cesarean section

BACKGROUND

Subarachnoid block is widely used for cesarean section due to the rapid induction, the complete analgesia, the low failure rate and the prevention of aspiration pneumonia. The addition of intrathecal opioids to local anesthetics seems to improve the quality of analgesia & prolong the duration of analgesia. Therefore we compared the effects of fentanyl 20 µg and sufentanil 2.5 µg, which were added to intrathecal hyperbaric bupivacaine.

METHODS

SEVENTY TWO HEALTHY TERM PARTURIENTS WERE RANDOMLY DIVIDED INTO THREE GROUPS: Group C (control), Group F (fentanyl 20 µg) and Group S (sufentanil 2.5 µg). In every group, 0.5% heavy bupivacaine was added according to the adjusted dose regimen by Harten et al. We observed the maximal level of the sensory block and motor block, the quality of intraoperative analgesia, the duration of effective analgesia and the side effects.

RESULTS

There were significant differences between the control and the fentanyl 20 µg and sufentanil 2.5 µg groups for the degree of muscle relaxation, the quality of intraoperative analgesia, the maximal sedation level and the duration of effective analgesia. The frequencies of side effects such as nausea and pruritis in the opioid groups were higher than those in the control group. But there were no differences between fentanyl 20 µg and sufentanil 2.5 µg for the frequencies of nausea and pruritis.

CONCLUSIONS

The addition of fentanyl 20 µg or sufentanil 2.5 µg for spinal anesthesia provides adequate intraoperative analgesia without significant adverse effects on the mother and neonate.

Therapy of pruritus

IMPORTANCE OF THE FIELD

Pruritus is the predominant symptom of skin disease. Owing to the poorly understood pathophysiology, the development of effective treatment modalities for pruritus has proven to be particularly difficult. At present, there is no universally accepted therapy for itch. The purpose of this review is to provide an update on the treatment of pruritus.

AREAS COVERED IN THIS REVIEW

An overview of current, emerging and possible future therapies for pruritus is provided.

WHAT THE READER WILL GAIN

Insights into possible treatment regimes for pruritus in different clinical scenarios.

TAKE HOME MESSAGE

The therapy of pruritus is challenging and at present takes on an individualistic approach. Recent advancements in the mechanisms that underlie this distressing symptom have identified new targets for future therapy.

Postoperative pain management in the elderly undergoing thoracic surgery

The management of postoperative pain in the elderly represents a considerable challenge because these patients are generally at higher risk for postoperative complications. There are several analgesic options, some of which may influence perioperative morbidity in this high-risk group of patients. Although use of regional analgesia, particularly epidural analgesia is associated with some benefits, including a decrease in perioperative morbidity, there are side effects and complications (eg, medication-related side effects, epidural hematoma, infection) from these and other techniques, and the clinician should evaluate the benefits and risks of each technique on an individual basis. Nevertheless, the available data suggest that use of regional analgesic techniques (ie, epidural and paravertebral catheters) is associated with a decrease in perioperative pulmonary complications.

[Opioid-induced pruritus. Mechanisms and treatment regimens]

Substantial progress has been achieved in recent years in research on the interaction between pain and pruritus. Over and above the known inhibition of pruritus by painful stimuli (e.g. scratching), a foundation for the explanation of opioid-induced pruritus was laid through the discovery of pruritus-specific neuronal processing channels. Although traditionally the degranulating effect of opioids on mast cells was assumed to be the essential mechanism, it is now clear that opioids can also induce itching at the spinal level. Neurons of the dorsal horn of the pain system inhibit spinal itch neurons. If this inhibition is weakened by opioids, the disinhibited itch neurons become active and mediate itching, without stimulation of the primary afferent peripheral nerves. Spinal triggering of itching is observed in particular by activation of mu-opioid receptors (mu-OR), while kappa-OR surprisingly suppress itch. The therapeutic implications of this interaction will be described.

Prophylactic mirtazapine reduces intrathecal morphine-induced pruritus

BACKGROUND

Activation of the serotonergic system is an important factor in the pathogenesis of intrathecal morphine-induced pruritus. Mirtazapine is a new antidepressant that selectively blocks 5-HT(2) and 5-HT(3) receptors. We therefore tested the hypothesis that preoperative mirtazapine would reduce the incidence of intrathecal morphine-induced pruritus.

METHODS

One hundred and ten ASA I patients undergoing lower limb surgery under spinal anaesthesia were randomly allocated into two equal groups and received either mirtazapine 30 mg or an orally disintegrating placebo tablet 1 h before operation in a prospective, double-blinded trial. All patients received an intrathecal injection of 15 mg of 0.5% isobaric bupivacaine and 0.2 mg preservative-free morphine. The occurrence and the severity of pruritus were assessed at 3, 6, 9, 12, and 24 h after intrathecal morphine.

RESULTS

Pruritus was significantly more frequent in the placebo group compared with the mirtazapine group (75% vs 52%, respectively; P=0.0245). The time to onset of pruritus in the two groups was also significantly different. The patients who experienced pruritus in the placebo group had a faster onset time than that in the mirtazapine group [mean (sd): 3.2 (0.8) vs 7.2 (4.1) h, P<0.0001].

CONCLUSIONS

Mirtazapine premedication prevents pruritus induced by intrathecal morphine in patients undergoing lower limb surgery with spinal anaesthesia.

Histamine-induced itch and its relationship with pain

Itch is one of the major complications of skin diseases. Although there are various substances that induce itch or pruritus, it is evident that histamine is the best known endogenous agent that evokes itch. Even though histamine-induced itch has been studied for some time, the underlying mechanism of itch is just beginning to emerge. Although various downstream signaling pathways of histamine receptors have been revealed, more studies are required to determine the cause of histamine-induced itch. It appears that itch and pain involve different neuronal pathways. Pain generally inhibits itch, which indicates an inter-communication between the two. Complex interactions between itch and pain may be expected based on reports on disease states and opioids. In this review, we discuss the molecular mechanism and the pharmacological aspects of histamine-induced itch. Especially, the underlying mechanism of TRPV1 (an anti-pruritus target) has been determined to some extent.

Effect of prophylactic 5-HT3 receptor antagonists on pruritus induced by neuraxial opioids: a quantitative systematic review

Pruritus is a frequent adverse event observed after neuraxial administration of opioids. Central 5-hydroxytryptamine subtype 3 (5-HT3) receptors may be activated in this process. This systematic review aimed to evaluate the efficacy of prophylactic 5-HT3 receptor antagonists on neuraxial opioid-induced pruritus. We searched Medline, Embase, and Cochrane Collaboration Library databases. Studies were evaluated with the Oxford Validity Scale. Studies with a score of 3 or more and reporting prophylactic administration of 5-HT3 receptor antagonists vs placebo were included. Fifteen randomized double-blind controlled trials (n=1337) were selected. 5-HT3 antagonists (n=775) significantly reduced pruritus [odds ratio (OR) 0.44 (95% confidence interval, 95% CI, 0.29-0.68), P=0.0002, number-needed-to-treat (NNT) 6 (95% CI, 4-14)], the treatment request for pruritus [OR 0.58 (95% CI, 0.43-0.78), P=0.0003, NNT 10 (95% CI, 7-20)], the intensity of pruritus [weighted mean difference (WMD) -0.35 (95% CI, -0.59 to -0.10), P=0.007], the incidence and the intensity of postoperative nausea and vomiting (PONV), and the need of rescue treatment [respectively, Peto odds ratio (Peto OR) 0.43 (95% CI, 0.31-0.58), P<0.00001, NNT 7 (95% CI, 6-10); WMD -0.12 (95% CI, -0.24 to 0.00), P=0.05 and OR 0.42 (95% CI, 0.20-0.86), P=0.02, NNT 8 (95% CI, 5-35)]. However, the funnel plot was asymmetric, suggesting a risk of publication bias. 5-HT3 receptor antagonists may be an effective strategy in preventing neuraxial opioid-induced pruritus and PONV. Further large randomized controlled trials are required to confirm these findings.