Establishing Minimal Clinically Important Differences in Quality of Life Measures in Opioid-Induced Constipation.

BACKGROUND & AIMS: Opioids have a role in chronic pain management. However, opioid-induced constipation may cause patients to skip or reduce opioid doses, leading to inadequate pain relief and negatively impacting quality of life. We sought to establish a minimal clinically important difference to understand whether changes in quality of life scores are of value to patients. METHODS: Integrated data from the double-blind, controlled, phase 3 COMPOSE-1 and COMPOSE-2 trials of naldemedine in chronic noncancer pain and opioid-induced constipation were used to determine minimal clinically important differences using Patient Assessment of Constipation Symptoms (PAC-SYM) and Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaires. Patients completed the questionnaires (5-point Likert scale; predose, Weeks 2, 4, and 12), kept a daily log of Bowel Movement and Constipation Assessment, and rated satisfaction at end of study. Minimal clinically important differences were computed using an anchor-based method with 6 anchors: 5 from the Bowel Movement and Constipation Assessment and 1 from patient satisfaction. Threshold values for each anchor were set to define responders versus nonresponders based on score definitions. Clinically meaningful cutoff values for changes in PAC-SYM and PAC-QOL scores were determined using receiver operating characteristic curves. RESULTS: Data from 1095 patients (549, naldemedine; 546, placebo) were analyzed. The area under the curve for the receiver operating characteristic curves (ranges, 0.719 to 0.798 for PAC-SYM and 0.734 to 0.833 for PAC-QOL) indicated that both instruments can discriminate responders and nonresponders for each anchor. PAC-SYM cutoff values ranged from -1.04 to -0.83; PAC-QOL cutoff values ranged from -0.93 to -0.82. CONCLUSIONS: Based on data derived from the anchor method, reductions in PAC-SYM and PAC-QOL scores of >1.0 in patients with chronic noncancer pain and opioid-induced constipation are clinically meaningful. CLINICALTRIALS: gov Registration: NCT01965158; NCT01993940.

SoluMatrix® Diclofenac: Sustained Opioid-Sparing Effects in a Phase 3 Study in Patients with Postoperative Pain.

OBJECTIVES: To evaluate opioid rescue medication usage and the opioid-sparing effect of low-dose SoluMatrix® diclofenac developed using SoluMatrix Fine Particle Technology™ in a phase 3 study in patients experiencing pain following bunionectomy surgery. DESIGN: Multicenter, randomized, double-blind, parallel-group study (NCT01462435). SETTING: Four clinical research centers in the United States. SUBJECTS: Four hundred twenty-eight patients aged 18 to 65 years who experienced moderate-to-severe pain following bunionectomy surgery. METHODS: Patients were randomized to receive low-dose SoluMatrix diclofenac 35 mg or 18 mg capsules three times daily (35-mg group or 18-mg group), celecoxib 400 mg loading dose followed by 200-mg capsules twice daily (celecoxib 200-mg group), or placebo capsules postsurgery. Patients were permitted to receive opioid-containing rescue medication as needed. RESULTS: Significantly fewer patients who received SoluMatrix diclofenac 35 mg or 18 mg or celecoxib required rescue medication during 0-24 h and >24-48 h postsurgery compared with placebo. Patients in the SoluMatrix diclofenac 35 mg or 18 mg groups or in the celecoxib group used fewer mean rescue medication tablets over 0-24 h and >24-48 h compared with placebo-treated patients. Patients in the SoluMatrix diclofenac 35 mg and 18 mg groups and in the celecoxib group also required rescue medication at later times and at slower rates compared with placebo-treated patients. No serious adverse effects occurred in patients receiving SoluMatrix diclofenac. CONCLUSIONS: SoluMatrix diclofenac at two dosage strengths demonstrated an opioid-sparing effect postoperatively in this phase 3 study. SUMMARY: The opioid-sparing effect following low-dose SoluMatrix diclofenac (35 mg or 18 mg three times daily) administration was evaluated in patients experiencing pain following bunionectomy. Significantly fewer patients receiving SoluMatrix diclofenac or celecoxib (400 mg loading, 200 mg twice daily) required rescue medication during 0-24 h and >24-48 h following bunionectomy compared with placebo. No serious adverse events were reported among patients who received SoluMatrix diclofenac. SoluMatrix diclofenac may reduce opioid usage in the postoperative setting in patients with acute pain.

Safety and Tolerability of Biphasic Immediate-Release/Extended-Release Oxycodone/Acetaminophen Tablets: Analysis of 11 Clinical Trials.

OBJECTIVES: To characterize the safety of immediate-release (IR)/extended-release (ER) oxycodone (OC)/acetaminophen (APAP). METHODS: Data were assessed from 9 phase 1 trials in healthy volunteers and recreational users of prescription opioids (N = 405), including 5 single-dose and 3 multidose open-label pharmacokinetic studies of IR/ER OC/APAP and active comparators; and 1 randomized, controlled, single-dose human abuse potential (HAP) study comparing IR/ER OC/APAP, IR OC/APAP, and placebo in recreational users of opioids; and 2 phase 3 trials (N = 701) including a 48-hour placebo-controlled safety and efficacy study in patients with moderate to severe postbunionectomy pain with a 14-day open-label safety extension and a long-term (≤ 35 days) open-label safety study in patients with chronic osteoarthritis pain or chronic low back pain. RESULTS: Adverse events (AEs) experienced by ≥ 10% of participants receiving IR/ER OC/APAP in all trials were pruritus, nausea, vomiting, dizziness, headache, and somnolence; these AEs occurred with similar frequency for equianalgesic doses of IR OC/APAP and IR OC but less frequently for IR tramadol HCl/APAP. In the HAP study, crushing IR/ER or IR OC/APAP tablets did not increase frequency of AEs. Constipation was experienced by < 10% of participants receiving IR/ER OC/APAP. No serious (SAE) or severe AEs were reported in phase 1 trials. In phase 3 trials of 8 reported SAEs, only 1 treatment-related SAE (hypersensitivity to placebo) required treatment discontinuation. No clinically meaningful changes in vital signs, oxygen saturation, electrocardiograms, or laboratory values were reported. CONCLUSIONS: Safety and tolerability of IR/ER OC/APAP are similar to other low-dose opioid/APAP analgesics.

Opioid Related Endocrinopathy.

OBJECTIVE: Millions of patients continue to require opioid analgesics for control of moderate to severe chronic pain, which is a disease that affects more Americans than cancer, heart disease, and diabetes combined. Common opioid adverse effects include constipation, sedation, and nausea. A lesser-known sequelae is opioid induced androgen deficiency (OPIAD). The objective of this review was to better characterize the effects of opioids on the endocrine system. METHODS: Published data were evaluated to identify links between opioid use and hypogonadism, as well as to describe proposed physiological mechanisms. RESULTS: Chronic opioid use may predispose to hypogonadism through alteration of the hypothalamic-pituitary-gonadal axis as well as the hypothalamic-pituitary-adrenal-axis. The resulting hypogonadism and hypotestosteronism may contribute to impaired sexual function, decreased libido, infertility, and osteoporosis- none of which may be clinically recognized as opioid related. CONCLUSIONS: OPIAD is a recognized consequence of long-term opioid therapy. Patients initiated or maintained on opioids should be queried about symptoms that might suggest hypogonadism including irregular menses, reduced libido, depression, fatigue, and hot flashes or night sweats. Some clinicians recommend assessment of baseline testosterone levels prior to initiating therapy. Additional data appear necessary to formulate guidelines regarding the diagnosis and management of OPIAD. Options include, rotating, reducing the dose or type, or cessation of opioid therapy or adding hormonal supplementation in the form of androgen replacement therapy. There are multiple formulations of testosterone available for replacement therapy, which is usually guided by laboratory measurements.

An Analysis of Rescue Medication Utilization from a 3-Month, Randomized, Double-Blind, Placebo-Controlled Study in Patients with Chronic Low Back Pain Treated with Single-Entity, Twice-Daily, Extended-Release Hydrocodone.

OBJECTIVE: To evaluate the durability of pain relief provided by a new formulation of single-entity, hydrocodone extended-release (ER) (Zohydro(®) ER) throughout the 12-hour dosing interval by examining patterns of rescue medication use. DESIGN: Phase 3, enriched enrollment, randomized withdrawal study with an open-label, conversion/titration phase (≤6 weeks) followed by a placebo-controlled, double-blind treatment phase (12 weeks). SETTING: Fifty-seven study sites in the United States enrolled patients. SUBJECTS: One hundred and fifty-one opioid-experienced subjects with moderate to severe chronic low back pain who were treated with hydrocodone ER once every 12 hours. METHODS: Post hoc analysis of rescue medication use by frequency and distribution of use following the morning and evening dose of hydrocodone ER. RESULTS: No rescue medication was used following the morning or evening dose of hydrocodone ER during 36.0% and 76.7% of the dosing days, respectively. Time distribution of rescue medication use showed that 79.3% of all rescue medication doses were administered following the morning dose, with the highest rate of usage (46.2%) occurring 4-8 hours postdose, followed by 18.7% and 14.4% usage 0-4 and 8-12 hours postdose, respectively. Examination of the three 4-hour intervals following the evening dose of hydrocodone ER revealed similar minimal rescue medication use (5.6-8.2%). CONCLUSIONS: End-of-dose failure was not observed based on the use of rescue medication after administration of single-entity, twice daily, hydrocodone ER capsules (Zohydro ER).

Efficacy and Tolerability of Subcutaneous Methylnaltrexone in Patients with Advanced Illness and Opioid-Induced Constipation: A Responder Analysis of 2 Randomized, Placebo-Controlled Trials.

BACKGROUND: Subcutaneous methylnaltrexone is efficacious and well tolerated in inducing bowel movements in patients with advanced illness and opioid-induced constipation (OIC); factors determining optimal responsiveness to OIC treatment, however, have not been elucidated. This post hoc responder analysis examined the influence of demographic and baseline characteristics on methylnaltrexone efficacy and tolerability in this population. METHODS: Data were pooled from 2 randomized, double-blind, placebo-controlled, phase 3 studies of subcutaneous methylnaltrexone (0.15 and 0.30 mg/kg) [ClinicalTrials.gov identifiers: Study 301 - NCT00401362; Study 302 - NCT00402038]. Subgroup analyses of the primary outcome, percentage of patients with rescue medication-free bowel movements (RFBM) within 4 hours of first dose, were conducted for age, sex, primary diagnosis, baseline constipation-related distress score, and baseline oral morphine equivalent dose. RESULTS: More than 50% of 165 patients treated with either methylnaltrexone dose experienced a RFBM within 4 hours vs. 14.6% of 123 placebo-treated patients (P < 0.0001 for both methylnaltrexone doses vs. placebo). Methylnaltrexone response was significantly greater than placebo response in all subgroups (P < 0.01). The largest differences vs. placebo were observed for patients taking methylnaltrexone 0.30 mg/kg with a noncancer primary diagnosis (70.0% [methylnaltrexone] vs. 12.8% [placebo]; P < 0.001) and for patients taking methylnaltrexone 0.30 mg/kg maintained on ≥ 150 mg/day baseline morphine equivalent doses (73.3% vs. 16.7%; P < 0.0001). Common adverse events were abdominal pain (pooled methylnaltrexone: 27.9%, placebo: 9.8%), flatulence (13.3%, 5.7%), and nausea (10.9%, 4.9%). Tolerability was comparable across subgroups. CONCLUSION: Subcutaneous methylnaltrexone provides a rapid, robust, and consistent RFBM response in patients with advanced illness and OIC. Methylnaltrexone 0.30 mg/kg may elicit particularly favorable responses in select patient populations.

Single-entity hydrocodone extended-release capsules in opioid-tolerant subjects with moderate-to-severe chronic low back pain: a randomized double-blind, placebo-controlled study.

OBJECTIVE: A single-agent, extended-release formulation of hydrocodone (HC) has been developed for treatment of chronic moderate-to-severe pain. This study was designed to examine the safety and efficacy of HC extended release in opioid-experienced adults with moderate-to-severe chronic low back pain (CLBP). METHODS: This multicenter, enriched enrollment, randomized withdrawal study comprised an open-label conversion/titration phase (≤6 weeks) followed by placebo-controlled, double-blind treatment (12 weeks). During the conversion/titration phase, subjects (N = 510) converted from their current opioid and were titrated to a stabilized dose of HC extended release (20-100 mg every 12 hours). During treatment, subjects (N = 151 per group) received HC extended release or placebo; rescue medication was permitted. The primary efficacy end point was mean change in average pain intensity from baseline to day 85. Response rates (30% pain improvement) and satisfaction (Subject Global Assessment of Medication) were assessed. RESULTS: Demographic and baseline characteristics were similar between groups. Mean ± SD change in average pain intensity score from baseline to day 85 was significantly lower in the HC extended-release treatment group vs placebo (0.48 ± 1.56 vs 0.96 ± 1.55; P = 0.008). Significantly more responders were in the treatment group (68% vs 31%; P < 0.001). Mean Subject Global Assessment of Medication scores increased significantly (0.8 ± 1.3 vs 0.0 ± 1.4; P < 0.0001), indicating greater satisfaction with HC extended release. The adverse event profile was consistent with other opioids. CONCLUSIONS: Extended-release HC is well tolerated and effective, without acetaminophen-associated risks of liver toxicity, for treatment of CLBP.

Burden of illness associated with peripheral and central neuropathic pain among adults seeking treatment in the United States: a patient-centered evaluation.

OBJECTIVE: The aim of this study was to evaluate patient-reported burden associated with peripheral and central neuropathic pain (NeP) by pain severity and NeP condition. DESIGN: Six hundred twenty-four subjects with one of six NeP conditions were recruited during routine office visits. Subjects consented to retrospective chart review and completed a one-time questionnaire (including EuroQol-5 dimensions, 12-item Short-Form Health Survey, Brief Pain Inventory-Short Form, Medical Outcomes Study Sleep Scale, Hospital Anxiety and Depression Scale, and demographic and clinical characteristics). Pain severity scores were used to stratify subjects by mild, moderate, and severe pain. Summary statistics and frequency distributions were calculated. Differences by severity level were compared using Kruskal-Wallis (continuous variables) and chi-square or Fisher's exact test (categorical variables). Effect size was computed with Cohen's d (mild vs severe). RESULTS: Subjects' mean age was 55.5. The majority (80.8%) had moderate or severe pain. Patient-reported outcomes (health status, physical and mental health, pain interference with function, sleep, anxiety, and depression) were significantly worse among subjects with greater pain severity (all P < 0.0001). Severe pain subjects were negatively impacted by ≥30% in each outcome compared with mild pain subjects; standardized effect size was moderate for anxiety (0.59) and large (>0.95) for all others. The observed burden was most substantial among chronic low back pain-NeP, although the pattern of disease burden was similar across the six NeP conditions. CONCLUSIONS: Subjects across NeP conditions exhibited high pain levels, which were significantly associated with poor function, compromised health status and sleep, and increased anxiety and depression. Results indicate substantial patient burden across broad NeP, particularly among subjects with severe pain.

An open-label pilot study evaluating the effectiveness of the heated lidocaine/tetracaine patch for the treatment of pain associated with carpal tunnel syndrome.

OBJECTIVES: Carpal tunnel syndrome (CTS) is a common entrapment neuropathy of the median nerve at the wrist that is characterized by pain, paresthesias, weakness, and loss of dexterity. This pilot study was conducted to evaluate the heated lidocaine/tetracaine patch (HLT patch) as a conservative treatment for pain of CTS. METHODS: Twenty adult patients (mean age = 44 ± 12 years) with pain secondary to unilateral CTS and electrodiagnostic evidence of mild-to-moderate CTS enrolled in this open-label study. Patients were treated with a single HLT patch placed over the junction of forearm and wrist on the palmar aspect of the wrist twice daily (morning and evening at 12-hour intervals) for 2 hours. At baseline and during the 2-week study, patients graded their pain intensity with an 11-point numerical rating scale (0 = no pain, 10 = worst imaginable pain). Pain interference with general activity, work, and sleep was evaluated with a similar 0-to-10-point scale. RESULTS: Fifteen patients completed the 14-day treatment period. Mean average pain intensity score decreased from 5.1 ± 1.5 at baseline to 2.5 ± 1.6 at end of study in the per-protocol population (P < 0.001). Two-thirds of the patients demonstrated clinically meaningful pain relief (≥ 30% reduction in average pain score), with 40% of the patients reaching this threshold by the third treatment day. Similar improvements were observed for pain interference scores. The HLT patch was generally well tolerated. CONCLUSION: The HLT patch resulted in clinically meaningful reduction in pain intensity in the majority of patients with mild-to-moderate CTS and may represent a targeted nonsurgical treatment for pain associated with CTS.

A review of duloxetine 60 mg once-daily dosing for the management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic osteoarthritis pain and low back pain.

BACKGROUND: Duloxetine is a selective dual neuronal serotonin (5-Hydroxytryptamine, 5-HT) and norepinephrine reuptake inhibitor (SSNRI). It is indicated in the United States for treatment of major depressive disorder (MDD), generalized anxiety disorder (GAD), and several chronic pain conditions, including management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic osteoarthritis (OA) pain and chronic low back pain (LBP). Its use for antidepressant and anxiolytic actions has been extensively reviewed previously. We here review the evidence for the efficacy of 60 mg once-daily dosing of duloxetine for chronic pain conditions. METHOD: The literature was searched for clinical trials in humans conducted in the past 10 years involving duloxetine. RESULTS: There were 199 results in the initial search. Studies not in the English language were excluded. We then included only studies of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain (OA and LBP). Studies of painful symptoms reported in mental health studies were excluded. This resulted in 32 studies. Articles that did not include a 60 mg/day daily dose as a study arm were excluded. This resulted in 30 studies, broken down as follows: 12 for diabetic peripheral neuropathy, 9 for fibromyalgia, 6 for LBP, and 3 for OA pain. CONCLUSIONS: The studies reviewed report that duloxetine 60 mg once-daily dosing is an effective option for the management of diabetic peripheral neuropathic pain, fibromyalgia, and chronic musculoskeletal pain due to chronic OA pain and chronic LBP. As these pains are often comorbid with MDD or GAD, duloxetine might possess the pharmacologic properties to be a versatile agent able to address several symptoms in these patients. With adequate attention to FDA prescribing guidance regarding safety and drug-drug interactions, duloxetine 60 mg once-daily dosing appears to be an effective option in the appropriate pain patient population.

Successful dose finding with sublingual fentanyl tablet: combined results from 2 open-label titration studies.

OBJECTIVE: This analysis was conducted to determine the likelihood of identifying an effective dose of fentanyl sublingual tablet during the initial titration phase of 2 clinical trials, to characterize the actual effective dose in patients achieving successful titration, and to examine the relationship between baseline characteristics and likelihood of achieving an effective dose. METHODS: Data were derived from 2 clinical trials (Study 1, n=131; Study 2, n=139) of fentanyl sublingual tablet in patients with cancer-associated breakthrough pain (BTP). Both trials comprised a 2-week titration phase and 12-month maintenance phase. The initial dose was 100 µg, titrated to an effective dose (producing effective relief of all BTP episodes on 2 consecutive days) of 100 to 800 µg. RESULTS: A total of 270 patients entered the titration phase. Mean (SD) baseline BTP opioid dose was 25.7 (88.9) mg morphine equivalent, and mean baseline around-the-clock opioid dose was 196.5 (151.6) mg morphine equivalent. Using conservative criteria for determining effective dose, 174 patients (64.4%) were successfully titrated to an effective dose (mean [SD], 498.2 [234.8] µg). The most frequent (27.6%) effective dose was 800 µg, and more than 85% of patients required an effective dose ≥300 µg. There were no significant relationships between any baseline characteristics and titration success. CONCLUSION: Despite stringent criteria, 64.4% of patients achieved an effective dose of fentanyl sublingual tablet within the dose range of 100 to 800 µg. Baseline characteristics were not identified to be associated with the likelihood of successful titration or with the actual effective dose of fentanyl sublingual tablet.

Abuse of immediate-release opioids and current approaches to reduce misuse, abuse and diversion.

Deaths from opioid overdoses have increased dramatically over the past few years. Given that immediate-release (IR) opioids account for most of the U.S. market share, and that abusers generally prefer IR opioids over extended-release (ER) opioids, it is not surprising that rates of abuse are higher for IR than ER opioids. IR opioids are widely prescribed, often without consideration for risks of abuse, misuse, and diversion. Prescription opioid abuse and misuse often begins through oral administration and progresses into non-oral routes (e.g. snorting, injecting) as abusers gain more experience; non-oral routes carry heightened safety concerns. Current approaches used for reducing opioid abuse include U.S. Food and Drug Administration regulations, state legislation, insurance company policies, the use of multimodal analgesic therapy, patient risk assessment and monitoring, limiting access to opioids by reducing IR opioid prescription quantity and length, prescription drug monitoring programs, patient education on proper disposal of unused medication and risks of diversion, as well as abuse-deterrent formulations. Albeit, most abuse-deterrent formulations have focused on ways to prevent the circumvention of ER characteristics rather than placing obstacles to abuse of IR opioid formulations. Reducing opioid abuse requires the combined efforts of multiple stakeholders, including prescribing clinicians, patients, pharmacists, nurses, insurance companies, government agencies, and pharmaceutical companies.

Efficacy and Safety of Cryoneurolysis for Treatment of Chronic Head Pain Secondary to Occipital Neuralgia: A Pilot Study.

PURPOSE: Treatment of chronic pain associated with occipital neuralgia (ON) is complex, and no consensus statement or guidelines have been published for ON management. This pilot study evaluated the efficacy and safety of cryoneurolysis for management of ON-associated chronic pain. PATIENTS AND METHODS: The study was a prospective, multicenter, nonrandomized cohort study assessing the degree and duration of clinical effect of cryoneurolysis therapy for reducing pain in patients diagnosed with unilateral or bilateral ON. The primary outcome measure was improvement in pain due to ON from baseline to day 7, measured on an 11-point numeric rating scale for pain. Secondary outcome measures included duration of treatment effects and safety events, including anticipated observations and adverse events. Treatment effect was assessed at days 7, 30, and 56 by asking the patient if they were continuing to experience a treatment effect, with potential responses of "effect," "no effect," or "no longer effective." A posttreatment questionnaire evaluated patient satisfaction. RESULTS: Twenty-six patients (9 men, 17 women) with a mean age of 49.1 years enrolled and completed the study. A total of 64% (16/25) of participants reported a clinically important improvement of ≥2 points in numeric rating scale pain scores at day 7; similar results persisted to day 30. Treatment effects were reported by 50% (13/26) of participants at day 30, with a continued effect reported by 35% (9/26) of participants at day 56. Overall, ~70% of participants were satisfied with treatment at 7, 30, and 56 days. No serious anticipated observations, adverse events, or unanticipated adverse device effects were reported. CONCLUSION: Cryoneurolysis provided significant relief from pain associated with ON ≤30 days after treatment and had an acceptable safety profile.

Characteristics of Analgesic Patch Formulations.

Topical and transdermal formulations are a common means of pharmaceutical drug delivery. If a drug is able to penetrate transcutaneously, the skin is an ideal site for the delivery of medications for both local (topical) and systemic (transdermal) effects. The administration of analgesics through the skin poses several potential advantages to those administered orally including compliance, the ability to deliver a drug to a peripheral target site and more stable and sustained plasma levels. One method of drug delivery is with the use of patch formulations - also known as patch systems. Typically, transdermal patches deliver medications intended to reach the systemic circulation, whereas topical patches are designed to keep medication localized for targeted delivery in proximity to the application site. There are a variety of technologies and materials utilized in patches, as well as penetration and formulation enhancers that ultimately affect the performance, efficacy and safety of the patch system. The degree of adherence to the skin is also of critical importance in drug delivery. Patches that lift up or fall off before the prescribed time period may represent a therapeutic failure and must be replaced, increasing patch utilization and cost to the healthcare system or to the patient. The added risk from accidental exposure makes poor patch adhesion a safety issue as well. A variety of analgesics are currently available as patch formulations including local anesthetics, capsaicin, nonsteroidal anti-inflammatory drugs and opioids. This review will highlight each of those patch delivery systems and introduce newer patch technologies that lend towards improved adhesion and compliance. Understanding the designs, limitations and benefits of patch systems will allow clinicians to select between these therapies when appropriate for their patients.

Evolving Pharmacotherapies for Pain: Drug Development.

The Chronic pain epidemic is a pressing public health crises facing the United States. Currently, more than 100 million Americans suffer from chronic pain, with chronic pain being among the most prevalent conditions and the leading cause of disability. Chronic pain disproportionately affects certain populations including women, low-income individuals, and older adults. This article focuses primarily on new molecular entities in development targeting various chronic pain receptors and new delivery technologies.

Tolperisone for the Treatment of Acute Muscle Spasm of the Back: Results from the Dose-Ranging Phase 2 STAR Study (NCT03802565).

OBJECTIVE: Use of skeletal muscle relaxants (SMRs) for acute muscle spasm is confounded by central nervous system adverse events (AEs), including somnolence. Tolperisone is an SMR that does not appear to be associated with somnolence. The aim of this study was to assess the safety and efficacy of tolperisone versus placebo in subjects with acute muscle spasm of the back. METHODS: STAR (NCT03802565) was a double-blind, randomized, placebo-controlled phase 2 study in subjects with back pain due to acute muscle spasm. Subjects were randomized 1:1:1:1:1 to tolperisone 50, 100, 150, or 200 mg three times daily (TID) or placebo for 14 days. The primary efficacy endpoint was subject-rated pain "right now" using a numeric rating scale on day 14. RESULTS: Subjects (tolperisone, n=337; placebo, n=78) were enrolled at 38 US clinical sites. Tolperisone was well tolerated, with AEs in 18.1% of subjects receiving tolperisone versus 14.1% of subjects receiving placebo. Headache (7.1%) and diarrhea (2.4%) were the most frequent AEs in tolperisone-treated subjects versus 3.8% and 0%, respectively, in placebo-treated subjects. Somnolence was reported in 1.2% and 2.6% of subjects treated with tolperisone and placebo, respectively. Mean change from baseline in numeric rating scale score of pain "right now" on day 14 was -3.5 for placebo versus -4.2, -4.0, -3.7, and -4.4 for tolperisone 50, 100, 150, and 200 mg TID, respectively (linear test of trend on the least-squares mean difference [treatment-placebo]; p=0.0539). In an analysis of pairwise estimates (treatment-placebo), the greatest numerical difference and significance were observed for tolperisone 200 mg TID (p=0.0040). Several secondary endpoints trended toward significance for tolperisone 200 mg TID versus placebo. CONCLUSION: Tolperisone 200 mg TID may be a promising treatment for acute muscle spasm, without the somnolence associated with SMRs. The safety and efficacy of tolperisone should be evaluated in a phase 3 trial.

Multimodal Treatment Patterns for Osteoarthritis and Their Relationship to Patient-Reported Pain Severity: A Cross-Sectional Survey in the United States.

PURPOSE: The purpose of this study was to assess how patient-reported pain is related to osteoarthritis (OA) treatment patterns in routine clinical practice. PATIENTS AND METHODS: Data were collected between February and May 2017 from 153 United States (US) primary care physicians, rheumatologists, and orthopedic surgeons. Each invited up to nine consecutive patients to rate their OA pain in the last week. Physicians provided demographic, clinical, and treatment information for patients, including nonpharmacologic therapies ever recommended, currently recommended over-the-counter (OTC) medications, and currently and ever prescribed medications for the management of OA. Findings for patients with mild (0─3), moderate (4─6), and severe current pain (7─10) were compared using appropriate statistics. RESULTS: Among the 841 patients (61% female; mean 65 years; 57% knee OA), 45% reported mild, 36% moderate, and 19% severe current OA pain. Current treatment modalities differed by pain severity (P<0.05). Most patients (70%) had been recommended nonpharmacologic therapy and 40% were currently recommended OTC medications. More patients with moderate (81%) or severe pain (78%) currently received prescription medications, with or without nonpharmacologic therapy, versus those with mild pain (67%). Overall, 47% of patients currently received just one prescription drug, while 49% had received one prescription drug ever. Nonsteroidal anti-inflammatory drugs (NSAIDs) were the most common current (58%) and ever received (88%) prescriptions. Current NSAID prescriptions were not associated with pain severity. Acetaminophen recommendations, opioid prescriptions (current and ever), and multiple prescription medications tried were numerically highest in the severe pain group (all P<0.05 by pain severity). In all groups, >80% of treatment switches were due to lack of efficacy. CONCLUSION: Real-life treatment patterns for OA in the US are significantly associated with current patient-reported pain. Combining nonpharmacologic and pharmacologic treatments is common but higher pain ratings are associated with multiple failed prescription treatments. Current use of acetaminophen and opioids, but not NSAIDs, increases alongside pain severity.

Efficacy and safety of naloxegol for opioid-induced constipation assessed by specific opioid medication, opioid dose, and duration of opioid use.

OBJECTIVE: Efficacy and safety of naloxegol, a peripherally acting µ-opioid receptor antagonist that significantly reduces opioid-induced constipation (OIC), were assessed for patient subgroups defined post hoc by baseline maintenance opioid characteristics. DESIGN: Post hoc, pooled analysis of data from two 12-week, randomized, double-blind, placebo-controlled, phase 3 studies. SETTING: Two hundred fifty-seven outpatient centers in the United States and Europe. PATIENTS: Patients with noncancer pain and OIC. INTERVENTIONS: Naloxegol (12.5 or 25 mg daily) or placebo. MAIN OUTCOMES MEASURES: The primary efficacy endpoint was the proportion of patients meeting response criteria at 12 weeks: at least three spontaneous bowel movements (SBMs)/wk and an increase from baseline of at least one SBM for ≥9 of 12 weeks and ≥3 of the last 4 weeks. No adjustments were made for multiplicity; all p values are descriptive. RESULTS: This analysis included 1,337 patients. Increases in the proportion of patients who achieved response at 12 weeks were observed with naloxegol 25 mg versus placebo in patients taking maintenance oxycodone, hydrocodone, morphine, or fentanyl (p ≤ 0.038); patients taking either ≥120 or <120 morphine-equivalent units at baseline (p ≤ 0.032); and patients treated with their current opioid for >6 months (p ≤ 0.035). Efficacy results were less robust with naloxegol 12.5 mg versus placebo. Adverse event incidences were generally comparable across treatment groups, regardless of opioid dose or duration of therapy but were numerically higher with some specific baseline opioids. CONCLUSION: In this post hoc, exploratory analysis, naloxegol 25 mg showed similar efficacy in treating OIC regardless of maintenance opioid type, dose, or duration of opioid use at baseline.

Long-term use of naldemedine in the treatment of opioid-induced constipation in patients with chronic noncancer pain: a randomized, double-blind, placebo-controlled phase 3 study.

The long-term safety of naldemedine, a peripherally acting µ-opioid receptor antagonist, was evaluated in patients with opioid-induced constipation and chronic noncancer pain in a 52-week, randomized, double-blind, phase 3 study. Eligible adults who could be on a routine laxative regimen were randomized 1:1 to receive once-daily oral naldemedine 0.2 mg (n = 623) or placebo (n = 623). The primary endpoint was summary measures of treatment-emergent adverse events (AEs). Additional endpoints included opioid withdrawal on the Clinical Opiate Withdrawal Scale and the Subjective Opiate Withdrawal Scale, pain intensity on Numeric Rating Scale, frequency of bowel movements, and constipation-related symptoms and quality of life on the Patient Assessment of Constipation Symptoms and Patient Assessment of Constipation Quality of Life scales, respectively. Treatment-emergent AEs (naldemedine, 68.4% vs placebo, 72.1%; difference: -3.6% [95% confidence interval: -8.7 to 1.5]) and treatment-emergent AEs leading to study discontinuation (6.3% vs 5.8%; difference: 0.5% [-2.2 to 3.1)] were reported for similar proportions of patients. Diarrhea was reported more frequently with naldemedine (11.0%) vs placebo (5.3%; difference: 5.6% [2.6-8.6]). There were no meaningful differences between groups in opioid withdrawal or pain intensity. Sustained significant improvements in bowel movement frequency and overall constipation-related symptoms and quality of life were observed with naldemedine (P ≤ 0.0001 vs placebo at all time points). Naldemedine was generally well tolerated for 52 weeks and did not interfere with opioid-mediated analgesia or precipitate opioid withdrawal. Naldemedine significantly increased bowel movement frequency, improved symptomatic burden of opioid-induced constipation, and increased patients' quality of life vs placebo.