Epidural naloxone reduces intestinal hypomotility but not analgesia of epidural morphine

Naloxone prolongs cutaneous nociceptive block by lidocaine in rats

We aimed to investigate the local anesthetic properties of naloxone alone or as an adjunct for the local anesthetic lidocaine. After the block of the cutaneous trunci muscle reflex (CTMR) with drugs delivery by subcutaneous infiltration, cutaneous nociceptive block was tested on the ratsꞌ backs. We demonstrated that naloxone, as well as lidocaine, elicited cutaneous analgesia dose-dependently. The relative potency in inducing cutaneous analgesia was lidocaine [22.6 (20.1 - 25.4) μmol/kg] > naloxone [43.2 (40.3 - 46.4) μmol/kg] (P < 0.05). On an equianesthetic basis [50% effective dose (ED₅₀ ), ED₂₅ , and ED₇₅ ], naloxone displayed a greater duration of cutaneous analgesic action than lidocaine (P < 0.01). Coadministration of lidocaine (ED₉₅ or ED₅₀ ) and ineffective-dose naloxone (13.3 μmol/kg) intensifies sensory block (P < 0.01) with prolonged duration of action (P < 0.001) compared with lidocaine (ED₉₅ or ED₅₀ ) alone or naloxone (13.3 μmol/kg) alone on infiltrative cutaneous analgesia. The preclinical data showed that naloxone is less potent than lidocaine as an infiltrative anesthetic, but its analgesic duration was longer than that of lidocaine. Furthermore, naloxone prolongs lidocaine analgesia, acting synergistically for nociceptive block.

Naloxone added to bupivacaine or bupivacaine-fentanyl prolongs motor and sensory block during supraclavicular brachial plexus blockade: a randomized clinical trial

BACKGROUND

In this study, the effect of naloxone on duration of supraclavicular brachial plexus block was evaluated. It was hypothesized that naloxone can increase the duration of neural blockade.

METHODS

Sixty-eight patients scheduled for surgery under supraclavicular brachial plexus block were randomly assigned to receive 30 ml bupivacaine (Group C); 30 ml bupivacaine with 100 μg of fentanyl (Group F); 30 ml bupivacaine with 100 ng naloxone (Group N); or 30 ml bupivacaine with 100 μg of fentanyl and 100 ng naloxone (Group N + F). Sensory and motor blockade were recorded at 5, 15, and 30 min following the block, and every 10 min following the end of surgery. Duration of sensory and motor block was considered to be the time interval between the complete block and the first postoperative pain and complete recovery of motor functions.

RESULTS

Sensory and motor onset times were the same in all groups. The duration of sensory and motor block in Group C (11.3 ± 1.7 h and 4.56 ± 1.0 h) and Group F (12.8 ± 3.3 h and 5.1 ± 2.0 h) were less than in the other groups (18.1 ± 2.2 h and 6.18 ± 1.0 h in Group N, and 15.8 ± 2.9 h and 6.53 ± 1.1 h in Group N + F, P < 0.0001).

CONCLUSION

Addition of naloxone to bupivacaine in supraclavicular brachial plexus block prolonged the duration of the neural blockade.

Management of postoperative ileus

Postoperative ileus is an abnormal pattern of gastrointestinal motility that is common after both abdominal and nonabdominal surgeries. There are many causes of ileus, including postoperative pain and the use of narcotics for analgesia, electrolyte imbalances, and manipulation of the bowel during surgery. Despite its prevalence, there is still no reliable treatment to prevent ileus or shorten its course. This article discusses the causes of postoperative ileus and the treatment options currently available. The literature on early refeeding, gum chewing, and the use of tube feeds is reviewed. In addition, new and experimental drugs currently in development are discussed.

An ultra-low dose of naloxone added to lidocaine or lidocaine-fentanyl mixture prolongs axillary brachial plexus blockade

INTRODUCTION

In this prospective, randomized, double-blind study, we evaluated the effect of an ultra-low dose of naloxone added to lidocaine and fentanyl mixture on the onset and duration of axillary brachial plexus block.

METHODS

One hundred twelve patients scheduled for elective forearm surgery under axillary brachial plexus block were randomly allocated to receive 34 mL lidocaine 1.5% with 3 mL of isotonic saline chloride (control group, n = 28), 34 mL lidocaine 1.5% with 2 mL (100 microg) of fentanyl and 1 mL of isotonic saline chloride (fentanyl group, n = 28), 34 mL lidocaine 1.5% with 2 mL saline chloride and 100 ng (1 mL) naloxone (naloxone group, n = 28), or 34 mL lidocaine 1.5% with 2 mL (100 microg) of fentanyl and 100 ng (1 mL) naloxone (naloxone + fentanyl group, n = 28). A multiple stimulation technique was used in all patients. After performing the block, sensory and motor blockades of radial, median, musculocutaneous, and ulnar nerves were recorded at 5, 15, and 30 min. The onset time of the sensory and motor blockades was defined as the time between the last injection and the total abolition of the pinprick response and complete paralysis, respectively. The duration of sensory and motor blocks was considered as the time interval between the complete block and the first postoperative pain and complete recovery of motor functions.

RESULTS

Sensory and motor onset times were longer in the naloxone (sensory onset time: 15 +/- 3, and motor onset time: 21 +/- 4) and naloxone + fentanyl group than control or fentanyl groups (sensory onset time: 10 +/- 3 min in control group, 10 +/- 4 min in fentanyl group, and 17 +/- 3 min in naloxone + fentanyl group, motor onset time: 15 +/- 5 min in control group, 14 +/- 7 min in fentanyl group, and 17.3 +/- 3.4 min in naloxone + fentanyl group) (P < 0.001). The duration of time to first postoperative pain and motor blockade was significantly longer in the naloxone (92 +/- 10 and 115 +/- 10 min) and naloxone + fentanyl groups (98 +/- 12 and 122 +/- 16 min) than control (68 +/- 7 and 89 +/- 11 min) and fentanyl groups (68 +/- 11 and 90 +/- 12 min) (P < 0.001). The time to first postoperative pain was significantly longer in the naloxone and naloxone + fentanyl groups than in the control or fentanyl groups (P < 0.001).

CONCLUSIONS

The addition of an ultra-low dose of naloxone to lidocaine 1.5% solution with or without fentanyl solution in axillary brachial plexus block prolongs the time to first postoperative pain and motor blockade but also lengthens the onset time.

Efficacy and safety of mu-opioid antagonists in the treatment of opioid-induced bowel dysfunction: systematic review and meta-analysis of randomized controlled trials

CONTEXT

Opioid-induced bowel dysfunction (OBD) is characterized by constipation, incomplete evacuation, bloating, and increased gastric reflux. OBD occurs both acutely and chronically, in multiple disease states, resulting in increased morbidity and reduced quality of life.

OBJECTIVE

To compare the efficacy and safety of traditional and peripherally active opioid antagonists vs conventional interventions for OBD.

DESIGN

We searched MEDLINE, the Cochrane Central Register of Controlled Trials and EMBASE. Additional reports were identified from the reference lists of retrieved articles.

STUDY SELECTION

Studies were included if they were randomized controlled trials that investigated the efficacy of mu-opioid antagonists for OBD.

DATA EXTRACTION

Data were extracted by two independent investigators and included demographic variables, diagnoses, interventions, efficacy, and adverse events.

RESULTS OF DATA SYNTHESIS

Twenty-two articles met inclusion criteria and provided data on 2,352 opioid antagonist-treated patients. The opioid antagonist investigated was alvimopan (eight studies), methylnaltrexone (six), naloxone (seven), and nalbuphine (one). Meta-analysis demonstrated that methylnaltrexone and alvimopan are efficacious in reversing opioid-induced increased gastrointestinal transit time and constipation, and that alvimopan is safe and efficacious in treating postoperative ileus. The incidence of adverse events with opioid antagonists was similar to placebo and generally reported as mild-to-moderate.

CONCLUSIONS

Insufficient evidence exists for the safety or efficacy of naloxone or nalbuphine in the treatment of OBD. Long-term efficacy and safety of any of the opioid antagonists is unknown, as is the incidence or nature of rare adverse events. Alvimopan and methylnaltrexone both show promise in treating OBD, but further data will be required to fully assess their place in therapy.

Mu-opioid antagonists for opioid-induced bowel dysfunction

BACKGROUND

Opioid-induced bowel dysfunction (OBD) is characterized by constipation, incomplete evacuation, bloating, and increased gastric reflux. OBD occurs both acutely and chronically, in multiple disease states, resulting in increased morbidity and reduced quality of life.

OBJECTIVES

To compare the efficacy and safety of traditional and peripherally active opioid antagonists versus conventional interventions for OBD.

SEARCH STRATEGY

We searched MEDLINE, the Cochrane Central Register of Controlled Trials and EMBASE in January 2007. Additional reports were identified from the reference lists of retrieved papers.

SELECTION CRITERIA

Studies were included if they were randomized controlled trials that investigated the efficacy of mu-opioid antagonists for OBD.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent review authors and included demographic variables, diagnoses, interventions, efficacy, and adverse events.

MAIN RESULTS

Twenty-three studies met inclusion criteria and provided data on 2871 opioid antagonist-treated patients. The opioid antagonists investigated were alvimopan (nine studies), methylnaltrexone (six), naloxone (seven), and nalbuphine (one). Meta-analysis demonstrated that methylnaltrexone and alvimopan were better than placebo in reversing opioid-induced increased gastrointestinal transit time and constipation, and that alvimopan appears to be safe and efficacious in treating postoperative ileus. The incidence of adverse events with opioid antagonists was similar to placebo and generally reported as mild-to-moderate.

AUTHORS' CONCLUSIONS

Insufficient evidence exists for the safety or efficacy of naloxone or nalbuphine in the treatment of OBD. Long-term efficacy and safety of any of the opioid antagonists is unknown, as is the incidence or nature of rare adverse events. Alvimopan and methylnaltrexone both show promise in treating OBD, but further data will be required to fully assess their place in therapy.

Enhanced Buprenorphine Analgesia with the Addition of Ultra-low-dose Naloxone in Healthy Subjects

Animal studies have demonstrated that co-administration of an ultra-low-dose opioid antagonist with an opioid agonist may result in enhanced analgesia. Investigation of this effect in humans has been limited and produced inconsistent findings, with previous reports suggesting that dose ratio may be critical to analgesic potentiation. The aim of the current investigation was to determine whether buprenorphine analgesia could be enhanced with the addition of ultra-low-dose naloxone among healthy volunteers, using a range of dose ratios. Tolerance to cold pressor pain was significantly greater with the combination of buprenorphine and naloxone compared to buprenorphine alone, and this effect was dose ratio dependent. Importantly, this enhanced analgesia occurred without an increase in adverse effects; indeed at some ratios, respiratory depression was attenuated. These findings demonstrate that the addition of ultra-low-dose naloxone can enhance the analgesic effect of buprenorphine in humans without a concurrent increase in side effects.

Epidural naloxone reduces postoperative nausea and vomiting in patients receiving epidural sufentanil for postoperative analgesia

BACKGROUND

Epidural opioids have excellent analgesic properties, but their side-effects limit their use in patient-controlled epidural analgesia. This study was designed to evaluate the effect of epidural naloxone on the side-effects of sufentanil, focusing on postoperative nausea and vomiting (PONV) in patients undergoing total knee replacement (TKR).

METHODS

After obtaining Institutional Review Board approval and informed consent, 50 patients undergoing unilateral TKR were randomly assigned to receive either sufentanil in ropivacaine alone (Group C, n = 25) or the same solution with naloxone (Group N, n = 25) for their postoperative epidural analgesia. Episodes of PONV and five-point-scaled nausea scores were evaluated at 6, 12, and 24 h after epidural analgesia was started. Visual analogue scale (VAS) score for pain and the incidence of sedation, pruritus, hypotension, and respiratory depression were also evaluated at each of three time points.

RESULTS

The nausea score in Group N was significantly lower than that in Group C. The VAS pain score at rest and on movement were significantly lower in Group N than in Group C at 24 h. Other opioid-induced side-effects were not significantly different.

CONCLUSIONS

Epidural naloxone was effective in reducing PONV induced by epidural sufentanil and additionally enhanced the analgesic effect. Therefore, concomitant infusion of a small dose of epidural naloxone should be considered to reduce PONV, especially in patients at greater risk for PONV.

Effects of low-dose naloxone on opioid therapy in pediatric patients: a retrospective case-control study

OBJECTIVE

To develop novel therapies that prevent opioid tolerance in critically ill children we examined the effects of low-dose naloxone infusions on patients' needs for analgesia or sedation.

DESIGN AND SETTING

Matched case-control study in a pediatric intensive care unit at a university children's hospital.

PATIENTS

We compared 14 pediatric ICU patients receiving low-dose naloxone and opioid infusions with 12 matched controls receiving opioid infusions.

MEASUREMENTS AND MAIN RESULTS

Opioid analgesia and sedative requirements were assessed as morphine- and midazolam-equivalent doses, respectively. No differences were observed between groups in opioid doses at baseline or during naloxone, but in the postnaloxone period opioid doses tended to be lower in the naloxone group. Compared to baseline the naloxone group required more opioids during naloxone but fewer opioids after naloxone. Total sedative doses were comparable at baseline in both groups, with no differences in the postnaloxone period. The naloxone group required less sedation after naloxone but sedation doses were unchanged in controls. The two groups did not differ in pain scores, sedation scores, or opioid side effects.

CONCLUSIONS

Naloxone did not reduce the need for opioid during the infusion period but tended to reduce opioid requirements in the postnaloxone period without additional need for sedation. Randomized clinical trials may examine the effects of low-dose naloxone on opioid tolerance and side effects in pediatric ICU patients requiring prolonged opioid analgesia.

Analgesia and local anesthesia during invasive procedures in the neonate

BACKGROUND

Preterm and full-term neonates admitted to the neonatal intensive care unit or elsewhere in the hospital are routinely subjected to invasive procedures that can cause acute pain. Despite published data on the complex behavioral, physiologic, and biochemical responses of these neonates and the detrimental short- and long-term clinical outcomes of exposure to repetitive pain, clinical use of pain-control measures in neonates undergoing invasive procedures remains sporadic and suboptimal. As part of the Newborn Drug Development Initiative, the US Food and Drug Administration and the National Institute of Child Health and Human Development invited a group of international experts to form the Neonatal Pain Control Group to review the therapeutic options for pain management associated with the most commonly performed invasive procedures in neonates and to identify research priorities in this area.

OBJECTIVE

The goal of this article was to review and synthesize the published clinical evidence for the management of pain caused by invasive procedures in preterm and full-term neonates.

METHODS

Clinical studies examining various therapies for procedural pain in neonates were identified by searches of MEDLINE (1980-2004), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2004), the reference lists of review articles, and personal files. The search terms included specific drug names, infant-newborn, infant-preterm, and pain, using the explode function for each key word. The English-language literature was reviewed, and case reports and small case series were discarded.

RESULTS

The most commonly performed invasive procedures in neonates included heel lancing, venipuncture, IV or arterial cannulation, chest tube placement, tracheal intubation or suctioning, lumbar puncture, circumcision, and SC or IM injection. Various drug classes were examined critically, including opioid analgesics, sedative/hypnotic drugs, nonsteroidal anti-inflammatory drugs and acetaminophen, injectable and topical local anesthetics, and sucrose. Research considerations related to each drug category were identified, potential obstacles to the systematic study of these drugs were discussed, and current gaps in knowledge were enumerated to define future research needs. Discussions relating to the optimal design for and ethical constraints on the study of neonatal pain will be published separately. Well-designed clinical trials investigating currently available and new therapies for acute pain in neonates will provide the scientific framework for effective pain management in neonates undergoing invasive procedures.

Adverse responses: sedation, analgesia and neuromuscular blocking agents in critically ill children

Advanced practice nurses (APNs) prescribe sedation, analgesia, and neuromuscular blocking agents in the management of critically ill children. Although most children are unscathed from the use of the medications, some suffer adverse responses. This article elucidates adverse responses to these medications for the APN, including withdrawal syndrome, muscle weakness, decreased gastric motility, corneal abrasions, and costs associated with these morbidities.

Methods for decreasing postoperative gut dysmotility

Postoperative disturbances of gastrointestinal function (postoperative ileus) are among the most significant side-effects of abdominal surgery for cancer. Without specific treatment, major abdominal surgery causes a predictable gastrointestinal dysfunction which endures for 4-5 days and results in an average hospital stay of 7-8 days. Ileus occurs because of initially absent and subsequently abnormal motor function of the stomach, small bowel, and colon. This disruption results in delayed transit of gastrointestinal content, intolerance of food, and gas retention. The aetiology of ileus is multifactorial, and includes autonomic neural dysfunction, inflammatory mediators, narcotics, gastrointestinal hormone disruptions, and anaesthetics. In the past, treatment has consisted of nasogastric suction, intravenous fluids, correction of electrolyte abnormalities, and observation. Currently, the most effective treatment is a multimodal approach. Median stays of 2-3 days after removal of all or part of the colon (colectomy) are now achievable. Recent discoveries have the potential to significantly reduce postoperative ileus in patients with cancer who have had abdominal surgery.

Endogenous opiates and behavior: 2001

This paper is the twenty-fourth installment of the annual review of research concerning the opiate system. It summarizes papers published during 2001 that studied the behavioral effects of the opiate peptides and antagonists. The particular topics covered this year include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology(Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

New concepts in acute and extended postoperative pain management in children

Increased knowledge of the pathophysiology of pain in children and an improved understanding of the pharmacology and pharmacodynamics of multiple agents have provided the clinician with a wide variety of tools to treat postoperative pain in children. The interest in a multimodal approach is kindled by the realization that the combination of a number of therapies can enhance analgesia with fewer untoward side effects. The expertise of other health care professionals should be tapped to open new avenues of treatment. Many therapies still require critical evidence-based evaluations to assess how well they work in larger patient populations. Dedication to research, compassionate patient care, and a willingness to teach the next generation of clinicians will bring us closer to the goal of safe and pain-free surgery.