Spotlight on naldemedine in the treatment of opioid-induced constipation in adult patients with chronic noncancer pain: design, development, and place in therapy

Management of Opioid-induced Constipation in Older Adults

Opioid-induced constipation (OIC) is a common condition in older adults who may not be responsive to traditional laxative therapy. OIC is defined as new or worsening constipation symptoms that occur with initiation of or altering the dose of opioid analgesia. For adult patients with OIC and noncancer pain, we recommend considering nonpharmacologic interventions (eg, dietary measures, increased physical activity, and biofeedback training) and over-the-counter laxatives, followed by prescription opioid receptor antagonists (methylnaltrexone, naloxegol, and naldemedine) if traditional over-the-counter laxatives fail. Other options may include lubiprostone, linaclotide, plecanatide, and prucalopride; however, these are not indicated for OIC specifically or studied in older adults. Because of the complex nature of absorption, distribution, metabolism, and excretion in the aging population, all agents used to treat OIC must be evaluated individually and reevaluated as patients continue to age. This review will serve as a guide to managing OIC in older adults.

Naldemedine for the treatment of opioid-induced constipation in adults with chronic noncancer pain

This review aims to summarize the efficacy data for naldemedine, a member of the novel peripherally acting μ-opioid receptor antagonists (PAMORAs), which gained US FDA approval for the treatment of opioid-induced constipation in adults with chronic noncancer pain-related syndromes in 2017. In Phase III trials, patients receiving naldemedine were significantly more likely to meet the primary end point ≥3 spontaneous bowel movements/week and an increase of ≥1 spontaneous bowel movement/week from baseline for at least 9/12 weeks compared to placebo (p < 0.0001). The most frequent adverse events were abdominal pain (8%) and diarrhea (7%). Based on available data, naldemedine appears to be an effective and safe first-line therapy for the treatment of opioid-induced constipation in adults with chronic noncancer pain.

Clinical Drug-Drug Interaction Studies to Evaluate the Effects of a P-Glycoprotein Inhibitor, CYP3A Inhibitors, and a CYP3A Inducer on the Pharmacokinetics of Naldemedine in Healthy Subjects

Background

Naldemedine is a peripherally acting μ-opioid receptor antagonist that is indicated to treat opioid-induced constipation.

Objectives

To assess the potential for drug-drug interactions between a single oral dose of naldemedine and the oral P-glycoprotein inhibitor cyclosporine, cytochrome P450 (CYP) 3A inhibitors itraconazole and fluconazole, and CYP3A inducer rifampin.

Methods

Three Phase 1, open-label studies were conducted in healthy subjects. In the P-glycoprotein inhibitor study, subjects received naldemedine 0.4 mg alone or coadministered with cyclosporine 600 mg. In the CYP3A inhibitors study, subjects in separate cohorts received naldemedine 0.2 mg alone or with itraconazole or fluconazole. In the CYP3A inducer study, subjects received naldemedine 0.2 mg alone or with rifampin 600 mg. Geometric mean ratios and 90 % confidence intervals were used to evaluate the effects of coadministered drugs on naldemedine maximum plasma concentration (C_max) and the area under the concentration-time curve (AUC). Safety assessments included occurrence of adverse events (AEs), laboratory parameters, vital signs, and electrocardiography results.

Results

A total of 56 subjects were enrolled (n = 14 in each cohort). Cyclosporine increased naldemedine AUC_0–inf 1.78-fold and C_max 1.45-fold. Itraconazole and fluconazole increased naldemedine AUC_0–inf 2.91-fold and 1.90-fold, and C_max 1.12-fold and 1.38-fold, respectively. Rifampin decreased naldemedine AUC_0–inf by 83% and C_max by 38%. Across studies, AEs were generally mild. Laboratory, vital sign, or electrocardiogram assessments produced no clinically significant findings.

Conclusions

Coadministration of naldemedine with a P-glycoprotein inhibitor or a strong/moderate CYP3A inhibitor increases naldemedine exposure; coadministration with a strong CYP3A inducer decreases its exposure. Coadministration of naldemedine with cyclosporine, itraconazole, fluconazole, or rifampin was generally safe and well tolerated.

Naldemedine is a targeted medication approved in the USA, Europe, and Japan for the treatment of opioid-induced constipation. Symptoms of constipation may include passing fewer stools than usual, having lumpy or hard stools, and/or straining to have bowel movements. In some cases, these symptoms are side effects of regular opioid use, which is often medically necessary for the management of moderate-to-severe pain. For naldemedine to be prescribed safely, doctors must know what other medications a patient is taking and how these medications may affect one another. This is commonly known as drug-drug interactions. Some drug-drug interactions may decrease how well a medication works, while other drug-drug interactions may increase the side effects experienced by a patient. In this paper, researchers report the results of three Phase 1 studies in healthy subjects examining how naldemedine interacts with other drugs. The drugs chosen for investigation are commonly evaluated in DDI studies and may affect the transport or metabolic pathway of naldemedine, including the P-glycoprotein inhibitor cyclosporine, the CYP3A inhibitors itraconazole and fluconazole, and the CYP3A inducer rifampin. These studies demonstrate that co-administration of naldemedine with each of these drugs impacted the pharmacokinetics of naldemedine. Cyclosporine, itraconazole, or fluconazole all increased naldemedine exposure, while rifampin decreased naldemedine exposure. For all drug combinations, observed side effects were generally mild and well tolerated. Additional testing, including vital signs and heart monitoring, did not reveal any other safety concerns. In conclusion, these findings support the cautious use of naldemedine in combination with cyclosporine, itraconazole or fluconazole. Concomitant use with rifampin should be avoided.

Incidence of opioid-induced constipation in Japanese patients with cancer pain: A prospective observational cohort study

This multicenter, prospective, observational cohort study assessed opioid induced constipation (OIC) in Japanese patients with cancer. Eligible patients had stable cancer and an ECOG PS of 0-2. OIC incidence based on the Rome IV diagnostic criteria was determined by patient diary entries during the first 14 days of opioid therapy. The proportion of patients with OIC was calculated for each 1-week period and the overall 2-week study period. Secondary measurements of OIC included the Bowel Function Index (BFI) score (patient assessment administered by physician), spontaneous bowel movements (SBMs) per week (patient assessment), and physician assessments. Medication for constipation was allowed. Two hundred and twenty patients were enrolled. The mean morphine-equivalent dose was 22 mg/day. By Rome IV criteria, the cumulative incidence of OIC was 56% (95% CI: 49.2%-62.9%); week 1, 48% (95% CI: 40.8%-54.6%); week 2, 37% (95% CI: 30.1%-43.9%). The cumulative incidence of OIC was lower in patients who received prophylactic agents for constipation (48% [95% CI: 38.1%-57.5%]) than in patients who did not (65% [95% CI: 55.0%-74.2%]). The cumulative incidences of OIC were 59% (95% CI: 51.9%-66.0%), 61% (95% CI: 54.3%-68.1%), and 45% (95% CI: 38.0%-51.8%) based on BFI scores, physician assessments, and SBM frequency, respectively. Frequency of BMs/week before starting opioids was the most influential factor for the occurrence of OIC. Utilization of prophylactic agents for constipation was associated with a modest effect on reducing the incidence of OIC. The incidences of OIC reported were variable depending on the diagnostic tool involved.

A meta-analysis of naldemedine for the treatment of opioid-induced constipation

INTRODUCTION

Opioid-induced constipation (OIC) is a common adverse effect in patients under long-term opioid therapy. Naldemedine is a novel peripherally acting μ-opioid receptor antagonists being developed for the treatment of OIC without affecting central analgesia. This meta-analysis is to assess the current evidence for efficacy and safety of naldemedine for the treatment of OIC. Areas covered: We searched through MEDLINE, EMBASE, Web of Science and Cochrane Library, 'ISRCTN Register' and'ClinicalTrials.gov' (up to Aug 2018). Our final review included five randomized clinical trials (1751 participants in total), three trials observed naldemedine for the treatment of OIC in non-cancer patients and two trials in cancer patients. A Random Effects model was used for all comparisons. Subgroup analyses for the following subgroups were carried out: naldemedine 0.1 mg; 0.2 mg; 0.4 mg; cancer patients; non-cancer patients. Expert opinion: Naldemedine improved the proportion of responders and spontaneous bowel movements frequency. The incidence of serious adverse effects (AEs) in naldemedine group was higher than placebo, especially in cancer patient subgroup. The AEs occurred in participants with naldemedine were mild to moderate and well tolerated during treatment. The results of this network meta-analysis will guide the future researchers in evaluating naldemedine for the treatment of OIC.

Absorption, distribution, metabolism, and excretion of radiolabeled naldemedine in healthy subjects

1. Naldemedine is a peripherally acting μ-opioid receptor antagonist for the treatment of opioid-induced constipation. 2. This phase 1 study investigated the absorption, distribution, metabolism and excretion of naldemedine, following a single oral 2-mg dose of [oxadiazole-¹⁴C]-naldemedine or [carbonyl-¹⁴C]-naldemedine to 12 healthy adult male subjects. Pharmacokinetic assessments were performed on blood, urine and fecal samples collected at defined intervals. 3. Naldemedine was the major circulating component in plasma with a median T_max of approximately 0.8-0.9 h and a geometric mean t_1/2,z of approximately 11 h. Total systemic exposures, AUC, of metabolites nor-naldemedine were less abundant than those of naldemedine (9% or 13% of AUC of naldemedine) and 16.2% or 18.1% of naldemedine was excreted as unchanged in urine after administration of [oxadiazole-¹⁴C]-naldemedine or [carbonyl-¹⁴C]-naldemedine, respectively, and benzamidine was the major radioactive component after administration of [oxadiazole-¹⁴C]-naldemedine (32.5% of administered dose). Overall, the recovery of total radioactivity was 92% (57.3% in urine; 34.8% in feces) after administration of [oxadiazole-¹⁴C]-naldemedine and 85% (20.4% in urine; 64.3% in feces) after administration of [carbonyl-¹⁴C]-naldemedine. 4. Our findings suggest that naldemedine is mainly metabolized to nor-naldemedine. Naldemedine was rapidly absorbed and well tolerated, with no major safety signals observed.