The effect of naloxone-3-glucuronide on colonic transit time in healthy men after acute morphine administration: a placebo-controlled double-blinded crossover preclinical volunteer study

Current overview of opioids in progression of inflammatory bowel disease; pharmacological and clinical considerations

Inflammatory bowel diseases (IBD) belong to a subgroup of persistent, long-term, progressive, and relapsing inflammatory conditions. IBD may spontaneously develop in the colon, resulting in tumor lesions in inflamed regions of the intestine, such as invasive carcinoma. The benefit of opioids for IBD treatment is still questionable, thereby we investigated databases to provide an overview in this context. This review demonstrates the controversial role of opioids in IBD therapy, their physiological and pharmacological functions in attenuating the IBD symptoms, and in improving inflammatory, oxidative stress, and the quality of life factors in IBD subjects. Data were extracted from clinical, in vitro, and in vivo studies in English, between 1995 and 2019, from PubMed, Google Scholar, Scopus, and Cochrane library. Based on recent reports, there are promising opportunities to target the opioid system and control the IBD symptoms. This study suggests a novel approach for future treatment of functional and inflammatory disorders such as IBD.

Opioid-Induced Constipation and Bowel Dysfunction: A Clinical Guideline

OBJECTIVE

To formulate timely evidence-based guidelines for the management of opioid-induced bowel dysfunction.

SETTING

Constipation is a major untoward effect of opioids. Increasing prescription of opioids has correlated to increased incidence of opioid-induced constipation. However, the inhibitory effects of opioids are not confined to the colon, but also affect higher segments of the gastrointestinal tract, leading to the coining of the term "opioid-induced bowel dysfunction."

METHODS

A literature search was conducted using Medline, EMBASE, and EMBASE Classic, and the Cochrane Central Register of Controlled Trials. Predefined search terms and inclusion/exclusion criteria were used to identify and categorize relevant papers. A series of statements were formulated and justified by a comment, then labeled with the degree of agreement and their level of evidence as judged by the Strength of Recommendation Taxonomy (SORT) system.

RESULTS

From a list of 10,832 potentially relevant studies, 33 citations were identified for review. Screening the reference lists of the pertinent papers identified additional publications. Current definitions, prevalence, and mechanism of opioid-induced bowel dysfunction were reviewed, and a treatment algorithm and statements regarding patient management were developed to provide guidance on clinical best practice in the management of patients with opioid-induced constipation and opioid-induced bowel dysfunction.

CONCLUSIONS

In recent years, more insight has been gained in the pathophysiology of this "entity"; new treatment approaches have been developed, but guidelines on clinical best practice are still lacking. Current knowledge is insufficient regarding management of the opioid side effects on the upper gastrointestinal tract, but recommendations can be derived from what we know at present.

Pharmacokinetics of Sublingual Buprenorphine and Naloxone in Subjects with Mild to Severe Hepatic Impairment (Child-Pugh Classes A, B, and C), in Hepatitis C Virus-Seropositive Subjects, and in Healthy Volunteers

BACKGROUND AND OBJECTIVES

Suboxone(®) is a sublingual tablet of buprenorphine/naloxone, approved for the treatment of opioid dependence. The objective of this study was to quantify the impact of hepatic impairment or hepatitis C virus infection on the pharmacokinetics of buprenorphine or naloxone and their major metabolites.

METHODS

Forty-three subjects received a single dose of a Suboxone 2.0/0.5-mg tablet. Blood samples were collected up to 168 h and pharmacokinetic parameters were calculated using non-compartmental analysis. Statistical analysis was performed using analysis of covariance.

RESULTS

Pharmacokinetic parameters were derived from 33 subjects. Compared with healthy subjects, for patients with severe hepatic impairment, total and peak exposures increased to 281.4 % [90 % confidence interval 187.1-423.3] and 171.8 % [117.9-250.2] for buprenorphine, 1401.9 % [707.6-2777.5] and 1129.8 % [577.2-2211.4] for naloxone. For moderate hepatic impaired subjects, naloxone total and peak exposure increased to 317.6 % [164.9-611.5] and 270.0  % [141.9-513.9]. For buprenorphine, only total exposure increased to 163.9 % [110.8-242.3]. Changes in maximum observed plasma concentration, area under the plasma concentration-time curve from time zero to time of the last quantifiable concentration, and area under the plasma concentration-time curve from time zero to infinity of buprenorphine or naloxone in subjects with mild hepatic impairment or with hepatitis C virus infection were within twofold of those of healthy subjects. Serious adverse events were not observed.

CONCLUSIONS

Severe and moderate hepatic impairment significantly increased exposure of naloxone and to a lesser extent of buprenorphine. Therefore, buprenorphine/naloxone combination products should generally be avoided in patients with severe hepatic impairment and may not be appropriate for patients with moderate hepatic impairment. However, buprenorphine/naloxone products may be used with caution for maintenance treatment in patients with moderate hepatic impairment who have initiated treatment on a buprenorphine product without naloxone [Registered at ClinicalTrials.gov as NCT01846455].

Physiology, signaling, and pharmacology of opioid receptors and their ligands in the gastrointestinal tract: current concepts and future perspectives

Opioid receptors are widely distributed in the human body and are crucially involved in numerous physiological processes. These include pain signaling in the central and the peripheral nervous system, reproduction, growth, respiration, and immunological response. Opioid receptors additionally play a major role in the gastrointestinal (GI) tract in physiological and pathophysiological conditions. This review discusses the physiology and pharmacology of the opioid system in the GI tract. We additionally focus on GI disorders and malfunctions, where pathophysiology involves the endogenous opioid system, such as opioid-induced bowel dysfunction, opioid-induced constipation or abdominal pain. Based on recent reports in the field of pharmacology and medicinal chemistry, we will also discuss the opportunities of targeting the opioid system, suggesting future treatment options for functional disorders and inflammatory states of the GI tract.

The optimal dose of prophylactic intravenous naloxone in ameliorating opioid-induced side effects in children receiving intravenous patient-controlled analgesia morphine for moderate to severe pain: a dose finding study

BACKGROUND

Opioid-induced side effects, such as pruritus, nausea, and vomiting are common and may be more debilitating than pain itself. A continuous low-dose naloxone infusion (0.25 μg/kg/h) ameliorates some of these side effects in many but not all patients without adversely affecting analgesia. We sought to determine the optimal dose of naloxone required to minimize opioid-induced side effects and to measure plasma morphine and naloxone levels in a dose escalation study.

METHODS

Fifty-nine pediatric patients (24 male/35 female; average age 14.2 ± 2.2 years) experiencing moderate to severe postoperative pain were started on IV patient-controlled analgesia morphine (basal infusion 20 μg/kg/h, demand dose 20 μg/kg, 5 doses/h) and a low-dose naloxone infusion (initial cohort: 0.05 μg/kg/h; subsequent cohorts: 0.10, 0.15, 0.25, 0.40, 0.65, 1, and 1.65 μg/kg/h). If 2 patients developed intolerable nausea, vomiting, or pruritus, the naloxone infusion was increased for subsequent patients. Dose/treatment success occurred when 10 patients had minimal side effects at a naloxone dose. Blood samples were obtained for measurement of plasma morphine and naloxone levels after initiation of the naloxone infusion, processed, stored, and measured by tandem mass spectrometry with electrospray positive ionization.

RESULTS

The minimum naloxone dose at which patients were successfully treated with a <10% side effect/failure rate was 1 μg/kg/h; cohort size varied between 4 and 11 patients. Naloxone was more effective in preventing pruritus than nausea and vomiting. Concomitant use of supplemental medicines to treat opioid-induced side effects was required at all naloxone infusion rates. Plasma naloxone levels were below the level of assay quantification (0.1 ng/mL) for infusion rates ≤0.15 μg/kg/h. At rates >0.25 μg/kg/h, plasma levels increased linearly with increasing infusion rate. In each dose cohort, patients who failed therapy had comparable or higher plasma naloxone levels than those levels measured in patients who did not fail treatment. Plasma morphine levels ranged between 3.52 and 172 ng/mL, and >90% of levels ranged between 10.2 and 61.6 ng/mL. Plasma morphine levels were comparable between patients who failed therapy and those patients who achieved symptom control.

CONCLUSIONS

Naloxone infusion rates ≥1 μg/kg/h significantly reduced, but did not eliminate, the incidence of opioid-induced side effects in postoperative pediatric patients receiving IV patient-controlled analgesia morphine. Patients who failed therapy generally had plasma naloxone and morphine levels that were comparable to those who had good symptom relief suggesting that success or failure to ameliorate opioid-induced side effects was unrelated to plasma levels.

Development and validation of a sensitive LC/MS/MS method for the simultaneous determination of naloxone and its metabolites in mouse plasma

A rapid, specific, and reliable LC-MS/MS based bioanalytical method was developed and validated for the simultaneous determination of naloxone (NLX) and its two metabolites, 6β-naloxol (NLL) and naloxone-3β-D-glucuronide (NLG) in mouse plasma. The optimal chromatographic behavior of these analytes was achieved on an Aquasil C18 column (50 mm × 2.1 mm, 5 μm) using reversed phase chromatography. The total LC analysis time per injection was 2.5 min with a flow rate of 1.0 mL/min with gradient elution. Sample preparation via protein precipitation with acetonitrile in a 96-well format was applied for analyses of these analytes. The analytes were monitored by electrospray ionization in positive ion multiple reaction monitoring (MRM) mode. Modification of collision energy besides chromatographic separation was applied to further eliminate interference peaks for NLL and NLG. The method validation was conducted over the curve range of 0.200/0.400/0.500 to 100/200/250 ng/mL for NLX/NLL/NLG, respectively, using 0.0250 mL of plasma sample. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels showed ≤ 6.5% relative standard deviation (RSD) and -8.3 to -2.5% relative error (RE). The method was successfully applied to determine the concentrations of NLX, NLL, and NLG in incurred mouse plasma samples.

What we have learned about colonic motility: normal and disturbed

PURPOSE OF REVIEW

Disorders of colonic motor and sensory function are common among children and adults and pose significant diagnostic and therapeutic challenges; the purpose of this review, therefore, was to critically assess the recent literature on this topic.

RECENT FINDINGS

Considerable progress has been made at the ultrastructural, molecular and electrophysiological level in understanding the normal functions of the muscles, nerves and interstitial cells that generate and control colonic motility. Furthermore, abnormalities in these cell types and in the interstitial cells of Cajal, in particular, have been identified in a number of disease states. Testing of colonic motor and sensory function in clinical practice continues to be a challenge due, in part, not only to the technical issues presented by accessing the organ but also to the intrinsic variability of its physiology. These have not been auspicious times for advances in the therapy of disturbed colonic motility; new agents or new applications for 'old' agents continue to be explored as are more innovative approaches such as those based on neural stimulation and cell therapy.

SUMMARY

Considerable progress has been made in understanding the basic pathophysiology of colonic dysmotility; clinical diagnostics and therapeutics continue to lag behind.

Endogenous opiates and behavior: 2008

This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (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).