Efficacy and tolerability of oral oxycodone and oxycodone/naloxone combination in opioid-naïve cancer patients: a propensity analysis

Managing Severe Cancer Pain with Oxycodone/Naloxone Treatment: A Literature Review Update

Severe cancer pain substantially affects patients' quality of life, increasing the burden of the disease and reducing the disability-adjusted life years. Although opioid analgesics are effective, they may induce opioid-induced bowel dysfunction (OIBD). Oxycodone/naloxone combination therapy has emerged as a promising approach to mitigate opioid-induced constipation (OIC) while providing effective pain relief. This review provides an updated analysis of the literature of the last decade regarding the use of oxycodone/naloxone in the management of severe cancer pain. Through a comprehensive search of databases, studies focusing on the efficacy, safety, and patient experience of oxycodone/naloxone's prolonged release in severe cancer pain management were identified. Furthermore, the literature discusses the mechanism of action of naloxone in mitigating OIC without compromising opioid analgesia. Overall, the evidence suggests that oxycodone/naloxone combination therapy offers a valuable option for effectively managing severe cancer pain while minimizing opioid-induced constipation, thereby improving patients' quality of life. However, further research is needed to optimize dosing regimens, evaluate long-term safety, and assess patient outcomes in diverse cancer populations.

Pharmacological prevention and treatment of opioid-induced constipation in cancer patients: A systematic review and meta-analysis

BACKGROUND

Cancer-related pain often requires opioid treatment with opioid-induced constipation (OIC) as its most frequent gastrointestinal side-effect. Both for prevention and treatment of OIC osmotic (e.g. polyethylene glycol) and stimulant (e.g. bisacodyl) laxatives are widely used. Newer drugs such as the peripherally acting µ-opioid receptor antagonists (PAMORAs) and naloxone in a fixed combination with oxycodone have become available for the management of OIC. This systematic review and meta-analysis aims to give an overview of the scientific evidence on pharmacological strategies for the prevention and treatment of OIC in cancer patients.

METHODS

A systematic search in PubMed, Embase, Web of Science and the Cochrane Library was completed from inception up to 22 October 2022. Randomized and non-randomized studies were systematically selected. Bowel function and adverse drug events were assessed.

RESULTS

Twenty trials (prevention: five RCTs and three cohort studies; treatment: ten RCTs and two comparative cohort studies) were included in the review. Regarding the prevention of OIC, three RCTs compared laxatives with other laxatives, finding no clear differences in effectivity of the laxatives used. One cohort study showed a significant benefit of magnesium oxide compared with no laxative. One RCT found a significant benefit for the PAMORA naldemedine compared with magnesium oxide. Preventive use of oxycodone/naloxone did not show a significant difference in two out of three other studies compared to oxycodone or fentanyl. A meta-analysis was not possible. Regarding the treatment of OIC, two RCTs compared laxatives, of which one RCT found that polyethylene glycol was significantly more effective than sennosides. Seven studies compared an opioid antagonist (naloxone, methylnaltrexone or naldemedine) with placebo and three studies compared different dosages of opioid antagonists. These studies with opioid antagonists were used for the meta-analysis. Oxycodone/naloxone showed a significant improvement in Bowel Function Index compared to oxycodone with laxatives (MD -13.68; 95 % CI -18.38 to -8.98; I2 = 58 %). Adverse drug event rates were similar amongst both groups, except for nausea in favour of oxycodone/naloxone (RR 0.51; 95 % CI 0.31-0.83; I2 = 0 %). Naldemedine (NAL) and methylnaltrexone (MNTX) demonstrated significantly higher response rates compared to placebo (NAL: RR 2.07, 95 % CI 1.64-2.61, I2 = 0 %; MNTX: RR 3.83, 95 % CI 2.81-5.22, I2 = 0 %). With regard to adverse events, abdominal pain was more present in treatment with methylnaltrexone and diarrhea was significantly more present in treatment with naldemedine. Different dosages of methylnaltrexone were not significantly different with regard to both efficacy and adverse drug event rates.

CONCLUSIONS

Magnesium oxide and naldemedine are most likely effective for prevention of OIC in cancer patients. Naloxone in a fixed combination with oxycodone, naldemedine and methylnaltrexone effectively treat OIC in cancer patients with acceptable adverse events. However, their effect has not been compared to standard (osmotic and stimulant) laxatives. More studies comparing standard laxatives with each other and with opioid antagonists are necessary before recommendations for clinical practice can be made.

A Multicenter Retrospective Observational Study Analyzing the Effect of Polypharmacy on Oxycodone Tolerability

Polypharmacy is becoming increasingly troublesome in the treatment of cancer. The aim of this study was to explore the effects of concomitant polypharmacy comprising drugs that inhibit CYP3A4 and/or CYP2D6 on the oxycodone tolerability in patients with cancer. We conducted a multicenter retrospective study encompassing 20 hospitals. The data used for the study were obtained during the first 2 wk of oxycodone administration. The incidence of oxycodone discontinuation or dose reductions due to side effects and oxycodone-induced nausea and vomiting (OINV) were compared between patients not treated with either inhibitor and those treated with concomitant CYP3A4 or CYP2D6 inhibitors. The incidence of oxycodone discontinuation or dose reductions in patients treated with ≥3 concomitant CYP2D6 inhibitors (18.2%) tended to be higher than that in patients without this treatment (8.2%; p = 0.09). Moreover, the incidence of OINV in patients treated with 2 concomitant CYP3A4 inhibitors (29.8%) was significantly higher than that in patients without this treatment (15.5%; p = 0.049). Multivariate analysis showed that more than two concomitant CYP3A4 inhibitors and no concomitant use of naldemedine were independent risk factors for OINV. Concomitant polypharmacy involving CYP3A4 inhibitors increases the risk of OINV. Therefore, medications concomitantly used with oxycodone should be optimized.

Hydrocodone, Oxycodone, and Morphine Metabolism and Drug-Drug Interactions

Awareness of drug interactions involving opioids is critical for patient treatment as they are common therapeutics used in numerous care settings, including both chronic and disease-related pain. Not only do opioids have narrow therapeutic indexes and are extensively used, but they have the potential to cause severe toxicity. Opioids are the classical pain treatment for patients who suffer from moderate to severe pain. More importantly, opioids are often prescribed in combination with multiple other drugs, especially in patient populations who typically are prescribed a large drug regimen. This review focuses on the current knowledge of common opioid drug-drug interactions (DDIs), focusing specifically on hydrocodone, oxycodone, and morphine DDIs. The DDIs covered in this review include pharmacokinetic DDI arising from enzyme inhibition or induction, primarily due to inhibition of cytochrome p450 enzymes (CYPs). However, opioids such as morphine are metabolized by uridine-5'-diphosphoglucuronosyltransferases (UGTs), principally UGT2B7, and glucuronidation is another important pathway for opioid-drug interactions. This review also covers several pharmacodynamic DDI studies as well as the basics of CYP and UGT metabolism, including detailed opioid metabolism and the potential involvement of metabolizing enzyme gene variation in DDI. Based upon the current literature, further studies are needed to fully investigate and describe the DDI potential with opioids in pain and related disease settings to improve clinical outcomes for patients. SIGNIFICANCE STATEMENT: A review of the literature focusing on drug-drug interactions involving opioids is important because they can be toxic and potentially lethal, occurring through pharmacodynamic interactions as well as pharmacokinetic interactions occurring through inhibition or induction of drug metabolism.

A Retrospective Observational Study of Factors Affecting the Efficacy of Concurrent Prescription of Naldemedine for Opioid-Induced Constipation Caused by Oxycodone Tablets

Naldemedine is indicated for the treatment of opioid-induced constipation (OIC), but reports on its efficacy in preventing OIC are few. Therefore, we retrospectively investigated factors affecting the efficacy of concurrent prescription of naldemedine on OIC. Outpatients with cancer who were started on oxycodone 10 mg/d were included in the study. The eligible patients were classified by their physicians into the following three groups: Group A used regular laxatives before the introduction of oxycodone and initiated naldemedine treatment simultaneously with oxycodone administration, Group B did not take laxatives before the introduction of oxycodone and started naldemedine simultaneously with oxycodone administration, and Group C had been administering regular laxatives before the introduction of oxycodone and were not prescribed naldemedine simultaneously with oxycodone treatment. The Support Team Assessment Schedule Japanese edition score for constipation, frequency of defecation, Bristol Stool Form Scale, sense of incomplete rectal evacuation, and development or worsening of straining to pass bowel movements were compared among the three groups before and after oxycodone administration. In Group B, there was significant worsening of the four parameters except for the sense of incomplete rectal evacuation, whereas Groups A and C did not present any changes. In logistic regression analysis, body weight ≥51.8 kg was a factor significantly decreasing the preventive effect of naldemedine on OIC, and regular use of laxatives was a factor significantly increasing the preventive effect of naldemedine on OIC. Thus, the initiation of naldemedine should be considered depending on the body weight and regular laxative use.

Effects of Electroacupuncture on Opioid-Induced Constipation in Patients With Cancer: Study Protocol for a Multicenter Randomized Controlled Trial

Background

Opioid-induced constipation (OIC) is one of the most prevalent adverse events associated with cancer patients who receive opioid analgesics for moderate to severe pain. Acupuncture may be an effective treatment for OIC. We designed this trial to assess the efficacy and safety of electroacupuncture for OIC in cancer patients.

Methods

This is a multicenter, sham-controlled, parallel-group, subject- and assessor-blinded randomized trial. A total of 100 cancer patients with OIC will be randomly assigned to either the electroacupuncture group or the sham electroacupuncture group at a ratio of 1:1. Patients in each group will receive a total of 24-session treatment over 8 weeks, three sessions a week and 30 min each session. Thereafter, patients will be followed up for another 8 weeks. The primary outcome will be the proportion of responders, defined as a patient who has ≥3 spontaneous bowel movements (SBMs)/wk and ≥ increase of 1 SBM from baseline simultaneously for at least 6 out of 8 weeks of the treatment period. The secondary outcomes will include the mean weekly SBMs and complete spontaneous bowel movements, the mean Bristol Stool Form Scale score for stool consistency, the mean score for straining of SBM, the total and subscale scores of Patient Assessment of Constipation-Symptom questionnaires, and the total and subscale scores of Patient Assessment of Constipation-Quality of Life questionnaire. Patients' global assessment of treatment effectiveness, patients' expectation toward the effectiveness of acupuncture and safety of acupuncture will also be assessed. All efficacy analyses will be performed in the intention-to-treat population.

Discussion

To improve the adherence to intervention protocols, the majority of the participants will be recruited from an inpatient setting. The results will help to determine the clinical effects and safety of electroacupuncture for the treatment of OIC among patients with cancer.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: NCT03797586, registered on 4 January 2019, https://clinicaltrials.gov/ct2/show/NCT03797586.

Effectiveness of Naldemedine Compared with Magnesium Oxide in Preventing Opioid-Induced Constipation: A Randomized Controlled Trial

Simple Summary

Opioids are used in cancer pain management, however, their continuous use may not be tolerable owing to adverse effects such as constipation, sleepiness, nausea, and respiratory depression. Opioid-induced constipation reduces the quality of life of patients, and osmotic laxatives are conventionally recommended for preventing opioid-induced constipation. Recently, naldemedine, a peripherally acting μ-opioid receptor antagonist, can be used to safely and effectively treat opioid-induced constipation based on its etiological mechanism, without affecting central analgesia. In this study, we compared the effectiveness of magnesium oxide with that of naldemedine in preventing opioid-induced constipation. Naldemedine significantly prevented deterioration in the quality of defecation (the Japanese Patient Assessment of Constipation Quality of Life and complete spontaneous bowel movement) and reduced gastrointestinal adverse effects, mainly nausea, compared with magnesium oxide during 12-week administration.

Abstract

Opioid-induced constipation (OIC) may occur in patients receiving opioid treatment, decreasing their quality of life (QOL). We compared the effectiveness of magnesium oxide (MgO) with that of naldemedine (NAL) in preventing OIC. This proof-of-concept, randomized controlled trial (registration number UMIN000031891) involved 120 patients with cancer scheduled to receive opioid therapy. The patients were randomly assigned and stratified by age and sex to receive MgO (500 mg, thrice daily) or NAL (0.2 mg, once daily) for 12 weeks. The change in the average Japanese version of Patient Assessment of Constipation QOL (JPAC-QOL) from baseline to 2 weeks was assessed as the primary endpoint. The other endpoints were spontaneous bowel movements (SBMs) and complete SBMs (CSBMs). Deterioration in the mean JPAC-QOL was significantly lower in the NAL group than in the MgO group after 2 weeks. There were fewer adverse events in the NAL group than in the MgO group. Neither significant differences in the change in SBMs between the groups nor serious adverse events/deaths were observed. The CSBM rate was higher in the NAL group than in the MgO group at 2 and 12 weeks. In conclusion, NAL significantly prevented deterioration in constipation-specific QOL and CSBM rate compared with MgO.

Efficacy of duloxetine compared with opioid for postoperative pain control following total knee arthroplasty

Background

The purpose of this study was to assess the efficacy of duloxetine as an alternative to opioid treatment for postoperative pain management following total knee arthroplasty (TKA).

Methods

Among 944 patients, 290 (30.7%) of patients received opioid or duloxetine for pain control for 6 weeks when the pain Visual Analogue Scale (VAS) score was greater than 4 out of 10 at the time of discharge. 121 patients in the Opioid group and 118 in the Duloxetine group were followed up for more than one year. Preoperative and postoperative patient reported outcome measures (pain VAS score, Western Ontario and McMaster Universities OA Index (WOMAC) score were compared. The rate of further drug prescription (opioid or duloxetine) after 6 weeks of first prescription, 30-day readmission rate, and side effects were also investigated.

Results

There was no significant difference in pain VAS score, WOMAC Pain and Function score, at each time point between before and after surgery (all p>0.05). Fifteen (9.8%) patients in the opioid group and six (4.4%) patients in the duloxetine group were prescribed additional medication after first 6 weeks, showing no significant (p>0.05) difference in proportion. The 30-day readmission rate and the incidence of side effects were also similar (all p>0.05). There was no difference in the incidence of side effects between the two groups (p>0.05).

Conclusion

Duloxetine and opioid did not show any difference in pain control, function, and side effects for up to one year after TKA. Although large-scale randomized controlled trials are still required to further confirm the side effects of duloxetine, it can be considered as an alternative to opioid for postoperative pain control following TKA.

Oxycodone/naloxone prolonged-release tablets in patients with moderate-to-severe, chronic cancer pain: Challenges in the context of hepatic impairment

Opioids such as oxycodone are recommended in the management of moderate-to-severe, chronic cancer pain. All opioids can potentially cause constipation, which may be a significant barrier to their use. Multiple randomised clinical trials have shown that the use of naloxone as a peripherally acting mu-opioid receptor antagonist, in combination with oxycodone can prevent or reduce opioid-induced constipation while having equivalent analgesic efficacy to oxycodone alone. However, clinical experience has shown that unexpected events may occur in some patients when unrecognized liver impairment is present. We describe the underlying biological reasons and propose simple, but effective steps to avoid this unusual but potentially serious occurrence. In healthy individuals, naloxone undergoes extensive hepatic first pass metabolism resulting in low systemic bioavailability. However, in patients with hepatic impairment, porto-systemic shunting can increase systemic bioavailability of naloxone, potentially compromising the analgesic efficacy of oral naloxone-oxycodone combinations. This reduced first pass effect can occur in a range of settings that may not always be apparent to the treating clinician, including silent cirrhosis, non-cirrhotic portal hypertension and disruption of liver internal vasculature by metastases. Hepatic function test results correlate poorly with presence and extent of liver disease, and are not indicative of porto-systemic shunting. Presence of hepatic impairment should thus be considered when medication-related outcomes with oxycodone-naloxone combination are not as expected, even if liver function test results are normal.

Comparing the effectiveness of magnesium oxide and naldemedine in preventing opioid-induced constipation: a proof of concept, single institutional, two arm, open-label, phase II, randomized controlled trial: the MAGNET study

Background

Patients taking opioids are known to develop opioid-induced constipation (OIC), which reduces their quality of life. The aim of this study is to compare magnesium oxide with naldemedine and determine which is more effective in preventing OIC.

Methods

This proof-of-concept, prospective, randomized controlled trial commenced in Japan in March 2018. Initially, a questionnaire-based survey will be conducted targeting adult patients with cancer who concomitantly commenced opioid treatment and OIC prevention treatment. Patients will then be randomly allocated to a magnesium oxide group (500 mg thrice daily) or a naldemedine group (0.2 mg once daily). Each drug will be orally administered for 12 weeks. The primary endpoint is defined as any improvement in scores on the Japanese version of Patient Assessment of Constipation Quality of Life questionnaire (JPAC-QOL) from baseline to 2 weeks of treatment.

Discussion

The primary endpoint is change in JPAC-QOL score from baseline to 2 weeks of intervention. The key secondary endpoint will be change in spontaneous bowel movements at 2 and 12 weeks of intervention. This study will determine whether magnesium oxide or naldemedine is more effective for the prevention of OIC.

Trial registration

University Hospital Medical Information Network (UMIN) Clinical Trials Registry, UMIN000031891. Registered March 25, 2018.

Pharmacologic effects of naldemedine, a peripherally acting μ-opioid receptor antagonist, in in vitro and in vivo models of opioid-induced constipation

BACKGROUND

Naldemedine (S-297995) is a peripherally acting μ-opioid receptor antagonist developed as a once-daily oral drug for opioid-induced constipation (OIC) in adults with chronic noncancer or cancer pain. This study characterized the pharmacological effects of naldemedine in vitro and in vivo.

METHODS

The binding affinity and antagonist activity of naldemedine against recombinant human μ-, δ-, and κ-opioid receptors were assayed in vitro. Pharmacologic effects of naldemedine were investigated using animal models of morphine-induced inhibition of small and large intestinal transit, castor oil-induced diarrhea, antinociception, and morphine withdrawal.

KEY RESULTS

Naldemedine showed potent binding affinity and antagonist activities for recombinant human μ-, δ-, and κ-opioid receptors. Naldemedine significantly reduced opioid-induced inhibition of small intestinal transit (0.03-10 mg kg^-1 ; P < 0.05) and large intestinal transit (0.3-1 μmol L^-1 ; P < 0.05). Naldemedine (0.03-1 mg kg^-1 ) pretreatment significantly reversed the inhibition of castor oil-induced diarrhea by subcutaneous morphine (P < 0.01). Naldemedine (1-30 mg kg^-1 ) pretreatment (1 or 2 hours) did not alter the analgesic effects of morphine in a model measuring the latency of a rat to flick its tail following thermal stimulation. However, a significant delayed reduction of the analgesic effect of morphine was seen with higher doses of naldemedine (10-30 mg kg^-1 ). Some centrally mediated and peripherally mediated withdrawal signs in morphine-dependent rats were seen with naldemedine doses ≥3 and ≥0.3 mg kg^-1 , respectively.

CONCLUSIONS & INFERENCES

Naldemedine displayed potent binding affinity to, and antagonistic activity against, μ-, δ-, and κ-opioid receptors. Naldemedine tempered OIC in vivo without compromising opioid analgesia.

Oral prolonged-release Oxycodone-Naloxone: analgesic response, safety profile, and factors influencing the response in advanced cancer patients

BACKGROUND

Oxycodone-Naloxone (OXN) aims to reduce opioid-related constipation while being successfully analgesic.

METHODS

We evaluated the analgesic response, prevalence, and severity of side effects in 176 cancer patients with moderate to severe pain and treated with OXN. Patients were followed for 28 days and evaluated every seven. Pain intensity, changes of therapy, and adverse drug reactions were recorded at each visit. The primary efficacy endpoint was the proportion of responders (≥30% reduction of pain intensity from baseline to final) and final average pain score ≤4 on a 0-10 scale.

RESULTS

Average and worst pain intensity, and breakthrough pain (BTP) prevalence decreased over time and 81.3% of patients were responders. The starting daily dose of OXN was raised from 25.1±13.0 mg to 44.1±29.9 mg, and dose escalation >5%/day was observed in 19.4% of patients; 40.8-46.2% and 11.0-17.0% experienced any and severe grade of constipation during the follow-up visit, respectively. Digestive system tumor, thyroid endocrinopathies, psychological irritability, and BTP increased the risk of analgesic non-response.

CONCLUSIONS

OXN had strong analgesic effect in moderate to severe cancer pain patients: the safety profile is in line with the common adverse effects of opioids and severe constipation was uncommon. This article is protected by copyright. All rights reserved.

A randomized, double-blind, non-inferiority study of hydromorphone hydrochloride immediate-release tablets versus oxycodone hydrochloride immediate-release powder for cancer pain: efficacy and safety in Japanese cancer patients

Background

Hydromorphone is a standard opioid analgesic for cancer pain that, prior to this study, was not approved in Japan, where options for opioid switching are limited. We aimed to investigate the efficacy and safety of hydromorphone (DS-7113b) immediate-release tablets in opioid-naïve cancer patients with moderate to severe cancer pain.

Methods

Multicenter, active-controlled, randomized, double-blind, parallel-group, non-inferiority study of 183 cancer patients over 20 years of age at 50 clinical sites in Japan. Hydromorphone tablets or oxycodone hydrochloride powder was orally administered four times daily for 5 days. The initial doses of hydromorphone and oxycodone hydrochloride were 4 mg/day and 10 mg/day, respectively, and adjusted as necessary. Efficacy was evaluated as the intergroup difference (95% confidence interval [CI]) of the least squares mean by analysis of covariance, using the baseline visual analog scale (VAS) as a covariate for change in VAS score at treatment completion/discontinuation in the full analysis set.

Results

Non-inferiority of hydromorphone versus oxycodone was confirmed, with an intergroup difference (95% CI) in the least squares mean of -3.4 mm (-9.8 to 3.1 mm) for change in VAS scores, which was below the upper limit of the 95% CI at 10 mm, the non-inferiority limit determined during study planning. Adverse events occurred in 83.0% (73/88) of patients in the hydromorphone group and 77.4% (65/84) in the oxycodone group. The most frequently observed adverse events were somnolence, constipation, vomiting and nausea.

Conclusions

The efficacy and safety of hydromorphone tablets are equivalent to those of oxycodone immediate-release powder.

Randomized Phase III and Extension Studies of Naldemedine in Patients With Opioid-Induced Constipation and Cancer

Purpose Opioid-induced constipation (OIC) is a frequent and debilitating adverse effect (AE) of opioids-common analgesics for cancer pain. We investigated the efficacy and safety of a peripherally acting μ-opioid receptor antagonist, naldemedine (S-297995), for OIC, specifically in patients with cancer. Patients and Methods This phase III trial consisted of a 2-week, randomized, double-blind, placebo-controlled study (COMPOSE-4) and an open-label, 12-week extension study (COMPOSE-5). In COMPOSE-4, eligible adults with OIC and cancer were randomly assigned on a 1:1 basis to receive once-daily oral naldemedine 0.2 mg or placebo. The primary end point was the proportion of spontaneous bowel movement (SBM) responders (≥ 3 SBMs/week and an increase of ≥ 1 SBM/week from baseline). The primary end point of COMPOSE-5 was safety. Results In COMPOSE-4, 193 eligible patients were randomly assigned to naldemedine (n = 97) or placebo (n = 96). The proportion of SBM responders in COMPOSE-4 was significantly greater with naldemedine than with placebo (71.1% [69 of 97 patients] v 34.4% [33 of 96 patients]; P < .0001). A greater change from baseline was observed with naldemedine than with placebo in the frequency of SBMs/week (5.16 v 1.54; P < .0001), SBMs with complete bowel evacuation/week (2.76 v 0.71; P < .0001), and SBMs without straining/week (3.85 v 1.17; P = .0005). In COMPOSE-4, more patients treated with naldemedine than with placebo reported treatment-emergent AEs (TEAEs) (44.3% [43 of 97 patients] v 26.0% [25 of 96 patients]; P = .01); in COMPOSE-5, 105 (80.2%) of 131 of patients reported TEAEs. Diarrhea was the most frequently reported TEAE in COMPOSE-4 (19.6% [19 of 97 patients] v 7.3% [seven of 96 patients] with naldemedine v placebo) and COMPOSE-5 (18.3% [24 of 131 patients] with naldemedine). Naldemedine was not associated with signs or symptoms of opioid withdrawal and had no notable impact on opioid-mediated analgesia. Conclusion Once-daily oral naldemedine 0.2 mg effectively treated OIC and was generally well tolerated in patients with OIC and cancer.

A comparison between the administration of oral prolonged-release oxycodone-naloxone and transdermal fentanyl in patients with moderate-to-severe cancer pain: a propensity score analysis

BACKGROUND

Opioids are the most important pharmacological treatment for moderate-to-severe cancer pain, but side effects limit their use. Transdermal fentanyl (TDF) and oral prolonged-release oxycodone-naloxone (OXN-PR) are effective in controlling chronic pain, with less constipation compared to other opioids. However, TDF and OXN-PR have never been directly compared.

PATIENTS AND METHODS

Cancer patients with moderate-to-severe chronic pain were consecutively enrolled in two prospective 28-day trials, received either TDF or OXN-PR, and were assessed at baseline and after 7, 14, 21, and 28 days. The primary endpoint was 28-day analgesic response rate (average pain intensity decrease ≥30% from baseline). Other outcome measures included opioid daily dose changes over time; need for adjuvant analgesics; number of switches; premature discontinuation; presence and severity of constipation; and other adverse drug reactions. To compare the efficacy and the safety of TDF and OXN-PR, we used the propensity score analysis to adjust for heterogeneity between the two patient groups.

RESULTS

Three hundred ten out of 336 patients originally treated (119 TDF and 191 OXN-PR) were included in the comparative analysis. The amount of responders was comparable after TDF (75.3%) and OXN-PR administration (82.9%, not significant [NS]). The final opioid daily dose expressed as morphine equivalent was 113.6 mg for TDF and 44.5 mg for OXN-PR (p<0.0001). A daily opioid dose escalation >5% was less common after OXN-PR (19.3%) than after TDS administration (37.9%, p<0.0001). Opioid switches and discontinuation were similar in both groups. Severe constipation in the two groups was comparable (32.6% after TDF vs 24.7% after OXN-PR, NS). Nausea, vomiting, and dry mouth were significantly less frequent in the OXN-PR group than in the TDF group.

CONCLUSION

Despite a similar analgesic activity in moderate-to-severe cancer pain, OXN-PR is characterized by lower daily dosages, less need for drug escalation, and fewer side effects compared to TDF.

Pharmacokinetic Bioequivalence Studies of an Extended-Release Oxycodone Hydrochloride Tablet in Healthy Japanese Subjects Under Fasting and Fed Conditions Without an Opioid Antagonist

Oxycodone is a semisynthetic opioid used for the treatment of moderate to severe pain. Two separate studies were conducted to assess the pharmacokinetic bioequivalence of a newly formulated oxycodone hydrochloride extended-release tablet to a marketed oxycodone product in Japan under fasting and fed conditions. Each study was a randomized, open-label, single-dose, single-center, two-period, two-way crossover study. Healthy male Japanese subjects received the oxycodone 10-mg products under fasting and fed conditions. Blood samples were collected at specified time intervals, and plasma concentrations of oxycodone were analyzed using a validated liquid chromatography tandem mass spectrometry assay method. The pharmacokinetic parameters were determined via non-compartmental analysis. Pharmacokinetic metrics used for bioequivalence assessment were the maximum observed plasma concentration (C max) and the area under the concentration-time curve up to the last sampling time (AUC t ). A total of 24 healthy subjects were enrolled in each study. One subject withdrew after completion of the first sequence under fed conditions. The ratios of geometric least square means for C max and AUC t under fasting conditions were 1.1110 (90% confidence interval [CI] 1.0562-1.1687) and 0.9946 (90% CI 0.9670-1.0231), respectively. The ratios of geometric least square means for C max and AUCt under fed conditions were 1.1417 (90% CI 1.0959-1.1895) and 1.0135 (90% CI 0.9810-1.0470), respectively. The 90% CIs were within the predefined range (0.80-1.25). Both treatments were well tolerated when taken without an opioid antagonist in healthy Japanese subjects. Pharmacokinetic bioequivalence between test and reference formulations under fasting and fed conditions was concluded in terms of both rate and extent of absorption.

A randomized, double-blind study of hydromorphone hydrochloride extended-release tablets versus oxycodone hydrochloride extended-release tablets for cancer pain: efficacy and safety in Japanese cancer patients (EXHEAL: a Phase III study of EXtended-release HydromorphonE for cAncer pain reLief)

BACKGROUND

In Japan, there are limited options for switching opioid analgesics. Hydromorphone is an opioid analgesic that is routinely used instead of morphine for cancer pain; however, it is not yet available in Japan. The aim of this study was to assess the efficacy and safety of hydromorphone (DS-7113b) extended-release tablets in opioid-naïve patients with cancer pain not relieved by non-opioid analgesics.

SUBJECTS AND METHODS

This was a multicenter, randomized, double-blind, parallel-group trial. A double-dummy method was used for blinding. Each randomized subject received either hydromorphone extended-release tablets plus placebo oxycodone hydrochloride extended-release tablets 4 mg/day (n=88) or placebo hydromorphone extended-release tablets plus oxycodone hydrochloride extended-release tablets 10 mg/day (n=93) orally for 7 days (once-daily dosing for hydromorphone and twice-daily dosing for oxycodone). The doses were adjusted as necessary. Efficacy was evaluated by change in visual analog scale (VAS) score from baseline to completion of treatment.

RESULTS

The between-group difference in least squares mean changes in VAS score from baseline to completion or discontinuation of treatment was -0.4 mm (95% CI -5.9 to 5 mm) by analysis of covariance where the baseline VAS score was used as a covariate. The upper limit of the 95% CI was below 10 mm, which was predefined as the noninferiority limit. This verified the noninferiority of hydromorphone tablets relative to oxycodone tablets. The incidence of adverse events was 80.7% (71 of 88) in the hydromorphone group and 83.7% (77 of 93) in the oxycodone group. The most common adverse events were nausea, vomiting, somnolence, diarrhea, and constipation, most of which are commonly observed with opioid analgesics.

CONCLUSION

The efficacy and safety of hydromorphone extended-release tablets were equivalent to those of the oxycodone extended-release formulation.

Naldemedine versus placebo for opioid-induced constipation (COMPOSE-1 and COMPOSE-2): two multicentre, phase 3, double-blind, randomised, parallel-group trials

BACKGROUND

Opioid-induced constipation is a frequent side-effect of opioid treatment, and standard interventions have limited or inconsistent efficacy. This study assessed the efficacy and safety of naldemedine, a peripherally acting μ-opioid receptor antagonist, for the treatment of opioid-induced constipation in patients with chronic non-cancer pain.

METHODS

We report two double-blind, randomised, placebo-controlled trials in adults with chronic non-cancer pain and opioid-induced constipation. The first (COMPOSE-1) was done in 68 outpatient sites in seven countries and the second (COMPOSE-2) at 69 outpatient sites in six countries; both studies were done in Europe and the USA. Eligible patients were aged 18-80 years, did not use laxatives, and had a stable opioid regimen for treatment of chronic non-cancer pain with a total daily dose averaging at least 30 mg (morphine equivalent) for at least 1 month before screening. Patients were randomly assigned (1:1) to receive either oral naldemedine 0·2 mg or matching placebo once a day for 12 weeks. Randomisation was stratified by average total daily opioid dose (30-100 mg and >100 mg equivalents of oral morphine sulphate). The primary endpoint was proportion of responders. A responder had at least three spontaneous bowel movements (SBMs) per week with an increase from baseline of at least one SBM per week for at least 9 weeks of the 12-week treatment period including at least three of the last 4 weeks. Efficacy endpoints were analysed by intention to treat and the safety population included all patients who received at least one dose of study drug. These trials have both been completed and are registered with ClinicalTrials.gov, numbers NCT01965158 and NCT01993940.

FINDINGS

In COMPOSE-1, 547 patients were recruited between Aug 29, 2013, and Jan 22, 2015, and were randomly assigned to receive naldemedine (n=274) or placebo (n=273). Patients for COMPOSE-2 were recruited between Nov 4, 2013, and June 9, 2015; 553 patients were randomly assigned to receive naldemedine (n=277) or placebo (n=276). Five patients were enrolled at more than one site, so were excluded from the intention-to-treat population (COMPOSE-1: one per group; COMPOSE-2: one in the naldemedine group, two from the placebo group), with intention-to-treat group sizes of 273 in the naldemedine group and 272 in the placebo group in COMPOSE-1, and 276 in the naldemedine group and 274 in the placebo group in COMPOSE-2. The proportion of responders in both trials was significantly higher with naldemedine than with placebo in COMPOSE-1 (130 responders [47·6%] of 273 in the naldemedine group vs 94 responders [34·6%] of 272 in the placebo group, difference 13·0% [95% CI 4·8-21·3]; p=0·002) and in COMPOSE-2 (145 [52·5%] of 276 vs 92 [33·6%] of 274, difference 18·9% [10·8-27·0]; p<0·0001). Incidence of adverse events with naldemedine was similar to placebo (COMPOSE-1: 132 [49%] of 271 in the naldemedine group vs 123 [45%] of 272 in the placebo group; COMPOSE-2: 136 [50%] of 271 vs 132 [48%] of 274). Treatment-related adverse events were noted in 59 (22%) of 271 patients in the naldemedine group and 45 (17%) of 272 in the placebo group in COMOPOSE-1, and in 54 (20%) of 271 patients in the naldemedine group and 31 (11%) of 274 in the placebo group of COMPOSE-2; the between-group differences were largely due to gastrointestinal disorders, which were more common with naldemedine than placebo (COMPOSE-1: 40 [15%] patients in the naldemedine group vs 18 [7%] in the placebo group; COMPOSE-2: 42 [16%] vs 20 [7%]).

INTERPRETATION

Naldemedine treatment led to a significantly higher responder rate than did placebo and was generally well tolerated. These results support that naldemedine could be a new option for the treatment of opioid-induced constipation in patients with chronic non-cancer pain.

FUNDING

Shionogi & Co, Ltd.

Phase IIb, Randomized, Double-Blind, Placebo-Controlled Study of Naldemedine for the Treatment of Opioid-Induced Constipation in Patients With Cancer

Purpose This randomized, double-blind, multicenter study aimed to determine the dose of naldemedine, a peripherally-acting μ-opioid receptor antagonist, for future trials by comparing the efficacy and safety of three doses of naldemedine versus placebo in patients with cancer and opioid-induced constipation. Methods Patients ≥ 18 years old with cancer, an Eastern Cooperative Oncology Group performance status ≤ 2, who had been receiving a stable regimen of opioid analgesics for ≥ 2 weeks, had at least one constipation symptom despite laxative use, and no more than five spontaneous bowel movements (SBMs) during the past 14 days, were randomly assigned (1:1:1:1) to oral, once-daily naldemedine 0.1, 0.2, or 0.4 mg, or placebo, for 14 days. The primary end point was change in SBM frequency per week from baseline during the treatment period. Secondary end points included SBM responder rates, change from baseline in the frequency of SBM without straining, and complete SBM. Safety was also assessed. Results Of 227 patients who were randomly assigned, 225 were assessed for efficacy (naldemedine 0.1 mg, n = 55; 0.2 mg, n = 58; 0.4 mg, n = 56; placebo, n = 56) and 226 for safety. Change in SBM frequency (primary end point) was higher with all naldemedine doses versus placebo ( P < .05 for all comparisons), as were SBM responder rates and change in complete SBM frequency. Change in SBM frequency without straining was significantly improved with naldemedine 0.2 and 0.4 (but not 0.1) mg versus placebo (at least P < .05). Treatment-emergent adverse events were more common with naldemedine (0.1 mg: 66.1%; 0.2 mg: 67.2%; 0.4 mg: 78.6%) than placebo (51.8%); the most common treatment-emergent adverse event was diarrhea. Conclusion Fourteen-day treatment with naldemedine significantly improved opioid-induced constipation in patients with cancer and was generally well tolerated. Naldemedine 0.2 mg was selected for phase III studies.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 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, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

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.

Analgesic effectiveness and tolerability of oral oxycodone/naloxone and pregabalin in patients with lung cancer and neuropathic pain: an observational analysis

INTRODUCTION

Cancer-related pain has a severe negative impact on quality of life. Combination analgesic therapy with oxycodone and pregabalin is effective for treating neuropathic cancer pain. We investigated the efficacy and tolerability of a dose-escalation combination therapy with prolonged-release oxycodone/naloxone (OXN-PR) and pregabalin in patients with non-small-cell lung cancer and severe neuropathic pain.

METHODS

This was a 4-week, open-label, observational study. Patients were treated with OXN-PR and pregabalin. Average pain intensity ([API] measured on a 0-10 numerical rating scale) and neuropathic pain (Douleur Neuropathique 4) were assessed at study entry and at follow-up visits. The primary endpoint was response to treatment, defined as a reduction of API at T28 ≥30% from baseline. Secondary endpoints included other efficacy measures, as well as patient satisfaction and quality of life (Brief Pain Inventory Short Form), Hospital Anxiety and Depression Scale, and Symptom Distress Scale; bowel function was also assessed.

RESULTS

A total of 56 patients were enrolled. API at baseline was 8.0±0.9, and decreased after 4 weeks by 48% (4.2±1.9; P<0.0001 vs baseline); 46 (82.1%) patients responded to treatment. Significant improvements were also reported in number/severity of breakthrough cancer pain episodes (P=0.001), Brief Pain Inventory Short Form (P=0.0002), Symptom Distress Scale (P<0.0001), Hospital Anxiety and Depression Scale depression (P=0.0006) and anxiety (P<0.0001) subscales, and bowel function (P=0.0003). At study end, 37 (66.0%) patients were satisfied/very satisfied with the new analgesic treatment. Combination therapy had a good safety profile.

CONCLUSION

OXN-PR and pregabalin were safe and highly effective in a real-world setting of severe neuropathic cancer pain, with a high rate of satisfaction, without interference on bowel function.

Oxycodone and Naloxone Combination: A 12-Week Follow-up in 20 Patients Shows Effective Analgesia Without Opioid-Induced Bowel Dysfunction

Introduction

Opioid analgesics are widely regarded to be highly effective but are equally known for their side effects on the bowel. A new combination of the opioid analgesic oxycodone and naloxone has been developed to combat opioid-induced bowel dysfunction (OIBD) whilst still being effective as an analgesic. The aim of this observational study was to assess the analgesic efficacy of this new combination and to analyze its effect on bowel function.

Methods

Twenty-six patients underwent a trial of this new combination, with 21 patients reaching week 8 and 18 reaching week 12.

Results

A significant reduction was seen in the pain severity score at weeks 4, 8, and 12 (P < 0.05), and a significant improvement in the bowel function index was again seen at these points (P < 0.001 at week 4 and 12, P < 0.05 at week 8). In the patients’ global impression of change, 83.3% of patients rated the new medication as an improvement compared to their previous regimen, and 87.5% rated it overall as “good” or “very good.”

Conclusion

This small single-center study suggests that the use of ONC in selected patients could lead to an improvement in pain severity and pain interference with a significant improvement in OIBD. Compliance with the combination is good, and it is generally well tolerated.

Long-term efficacy and safety of oxycodone-naloxone prolonged release in geriatric patients with moderate-to-severe chronic noncancer pain: a 52-week open-label extension phase study

BACKGROUND

Two-thirds of older people suffer from chronic pain and finding valid treatment options is essential. In this 1-yearlong investigation, we evaluated the efficacy and safety of prolonged-release oxycodone-naloxone (OXN-PR) in patients aged ≥70 (mean 81.7) years.

METHODS

In this open-label prospective study, patients with moderate-to-severe noncancer chronic pain were prescribed OXN-PR for 1 year. The primary endpoint was the proportion of patients who achieved ≥30% reduction in pain intensity after 52 weeks of treatment, without worsening bowel function. The scheduled visits were at baseline (T0), after 4 weeks (T4), and after 52 weeks (T52).

RESULTS

Fifty patients completed the study. The primary endpoint was achieved in 78% of patients at T4 and 96% at T52 (P<0.0001). Pain intensity, measured on a 0-10 numerical rating scale, decreased from 6.0 at T0 to 2.8 at T4 and to 1.7 at T52 (P<0.0001). Mean daily dose of oxycodone increased from 10 to 14.4 mg (T4) and finally to 17.4 mg (T52). Bowel Function Index from 35.1 to 28.7 at T52. No changes were observed in cognitive functions (Mini-Mental State Examination evaluation), while daily functioning improved (Barthel Index from 53.1 to 61.0, P<0.0001). The Screener and Opioid Assessment for Patients with Pain-Revised score at 52 weeks was 2.6 (standard deviation 1.6), indicating a low risk of aberrant medication-related behavior. In general, OXN-PR was well tolerated.

CONCLUSION

This study of the long-term treatment of chronic pain in a geriatric population with OXN-PR shows satisfying analgesic effects achieved with a stable low daily dose, coupled with a good safety profile and, in particular, with a reduction of constipation, often present during opioid therapy. Our findings support the indications of the American Geriatrics Society, suggesting the use of opioids to treat pain in older people not responsive to acetaminophen or nonsteroidal anti-inflammatory drugs.