Celecoxib-tramadol co-crystal in patients with moderate-to-severe pain following bunionectomy with osteotomy: A phase 3, randomized, double-blind, factorial, active- and placebo-controlled trial.

BACKGROUND: Celecoxib-tramadol co-crystal (CTC) is a first-in-class analgesic co-crystal of celecoxib and racemic tramadol with an improved pharmacologic profile, conferred by the co-crystal structure, compared with its active constituents administered alone/concomitantly. AIM: We evaluated CTC in moderate-to-severe acute postoperative pain. MATERIALS AND METHODS: This randomized, double-blind, factorial, active- and placebo-controlled phase 3 trial (NCT03108482) was conducted at 6 US clinical research centers. Adults with moderate-to-severe acute pain following bunionectomy with osteotomy were randomized to oral CTC (200 mg [112 mg celecoxib/88 mg rac-tramadol hydrochloride] every 12 h), tramadol (50 mg every 6 h), celecoxib (100 mg every 12 h), or placebo for 48 h. Patients, investigators, and personnel were blinded to assignment. The primary endpoint was the 0-48 h sum of pain intensity differences (SPID0-48) in all randomized patients. Pain intensity was assessed on a 0-10 numerical rating scale (NRS). Safety was analyzed in patients who received study medication. Funded by ESTEVE Pharmaceuticals. RESULTS: In 2017 (March to November), 1323 patients were screened and 637 randomized to CTC (n = 184), tramadol (n = 183), celecoxib (n = 181), or placebo (n = 89). Mean baseline NRS was 6.7 in all active groups. CTC had a significantly greater effect on SPID0-48 (least-squares mean: -139.1 [95% confidence interval: -151.8, -126.5]) than tramadol (-109.1 [-121.7, -96.4]; p < 0.001), celecoxib (-103.7 [-116.4, -91.0]; p < 0.001), or placebo (-74.6 [-92.5, -56.6]; p < 0.001). Total treatment-emergent adverse events (TEAEs) were 358 for CTC and 394 for tramadol. Drug-related TEAEs occurred in 37.7% patients in the CTC group, compared with 48.6% in the tramadol group. There were no serious TEAEs/deaths. CONCLUSION: CTC provided greater analgesia than comparable daily doses of tramadol and celecoxib, with similar tolerability to tramadol. CTC is approved in the United States.

Efficacy and safety of fasinumab in patients with chronic low back pain: a phase II/III randomised clinical trial.

OBJECTIVES: To study the efficacy and safety of fasinumab in moderate-to-severe, chronic low back pain (CLBP). METHODS: In this phase II/III, double-blind, placebo-controlled study, patients with CLBP aged ≥35 years with inadequate pain relief/intolerance to acetaminophen, non-steroidal anti-inflammatory drugs and opioids were randomised to fasinumab 6 or 9 mg subcutaneous every 4 weeks (Q4W), 9 mg intravenous every 8 weeks (Q8W) or placebo. Primary endpoint was change from baseline to week 16 in average daily low back pain intensity (LBPI) numeric rating score. Key secondary efficacy variables included Roland-Morris Disability Questionnaire (RMDQ) and Patient Global Assessment (PGA). The results are based on a modified intent-to-treat analysis of 563/800 planned patients when enrolment was stopped early given emerging signals of joint risk in other osteoarthritis (OA) studies at doses being tested here. RESULTS: Significant placebo-adjusted LBPI reductions at week 16 were observed for fasinumab 9 mg Q4W and Q8W (least squares mean (standard error) -0.7 (0.3); both nominal p<0.05), but not 6 mg (-0.3 (0.3); p=0.39). RMDQ and PGA improvements to week 16 were greatest for fasinumab 9 mg intravenous. Numerically greater efficacy occurred in patients with, versus those without, peripheral OA (pOA) over 16 weeks. Treatment-emergent adverse events (AEs) occurred in 274/418 (65.6%) patients in the combined fasinumab groups and 94/140 (67.1%) placebo patients. Joint AEs, mostly rapid progressive OA type 1, were more frequent in the combined fasinumab groups (19 events in 16 patients (3.8%) vs 1 event in 1 patient (0.7%) for placebo); all except one occurred in pOA patients. CONCLUSIONS: Fasinumab highest doses, but not lower dose, improved both CLBP pain and function. Most joint AEs occurred in pOA patients, consistent with earlier findings in symptomatic OA. Further study is needed of patients with CLBP with and without pOA to determine optimal benefit-risk.

Effects of naltrexone exposure observed in two phase three studies with ALO-02, an extended-release oxycodone surrounding sequestered naltrexone.

OBJECTIVE: To evaluate the clinical effects of naltrexone following ALO-02 administration. DESIGN: Two phase three studies: an open-label, single-arm safety study, and a double-blind, placebo-controlled, randomized withdrawal, efficacy study (ClinicalTrials.gov identifiers: NCT01428583, NCT01571362). SETTING: Seventy US research centers. PATIENTS: Eight hundred and five patients with moderate-to-severe chronic noncancer pain (n = 395) or moderate-to-severe chronic low back pain (n = 410). INTERVENTIONS: Oral ALO-02 capsules (daily dose 20-160 mg oxycodone): openlabel titration followed by double-blind fixed dose ALO-02 or placebo (12 weeks) for the efficacy study; and open-label administration (≤12 months) for the safety study. MAIN OUTCOME MEASURES: Brief Pain Inventory-Short Form (BPI-sf), withdrawal-related adverse events, Clinical Opiate Withdrawal Scale (COWS), and naltrexone plasma concentrations. RESULTS: ALO-02 was received for = 30 days by 592 patients (73.5 percent), = 90 days by 348 patients (43.2 percent), and ≤361 days by 105 patients (13.0 percent). Maximum COWS scores were below the cutoff for mild withdrawal for the majority of patients: 86.6 percent of patients in the safety study, and for the efficacy study, 96.8 percent during titration and 95.0 percent during double-blind treatment. The frequency of quantifiable naltrexone plasma concentrations was similar between studies (18-23 percent of samples), and the levels were low, generally not exceeding 200 pg/mL. There was no apparent relationship between naltrexone plasma concentrations and COWS scores (total or change from baseline), or change from baseline in BPI-sf scores in the efficacy (R2 = 0.0184, 0.0224, and 0.0173, respectively) or safety studies (R2 = 0.0010, 0.0000, and 0.0122, respectively). CONCLUSIONS: Naltrexone plasma concentrations were low, not correlated with COWS or BPI-sf scores, and considered clinically insignificant.

HTX-011 reduced pain intensity and opioid consumption versus bupivacaine HCl in bunionectomy: phase III results from the randomized EPOCH 1 study.

BACKGROUND AND OBJECTIVES: There is a need for local anesthetics that provide consistent analgesia through 72 hours after surgery. This study evaluates the use of HTX-011 (bupivacaine and meloxicam in Biochronomerpolymer technology), an extended-release, dual-acting local anesthetic, in reducing both postoperative pain over 72 hours and postoperative opioid use when compared with bupivacaine hydrochloride (HCl) and saline placebo. Inclusion of low-dose meloxicam in HTX-011 is designed to reduce local inflammation caused by surgery, potentiating the analgesic effect of bupivacaine. Previously, significant synergy has been observed with bupivacaine and meloxicam with both given locally together. METHODS: EPOCH 1 was a randomized, double-blind, placebo-controlled and active-controlled phase III study in subjects undergoing a primary unilateral, distal, first metatarsal bunionectomy in which subjects received either a single intraoperative dose of HTX-011, immediate-release bupivacaine HCl or saline placebo. RESULTS: A total of 412 subjects were dosed. The results for the primary and all four key secondary endpoints were statistically significant in favor of HTX-011. HTX-011 demonstrated superior, sustained pain reduction through 72 hours, significantly reduced opioid consumption and resulted in significantly more opioid-free subjects compared with saline placebo and bupivacaine HCl. Safety was similar across groups with fewer opioid-related adverse events observed in the HTX-011 group. CONCLUSIONS: HTX-011 demonstrated significant reduction in postoperative pain through 72 hours with significant reduction in opioid consumption and a significant increase in the proportion of opioid-free subjects compared with saline placebo and the most widely used local anesthetic, bupivacaine HCl. TRIAL REGISTRATION NUMBER: NCT03295721.

Efficacy and safety of intravenous tanezumab for the symptomatic treatment of osteoarthritis: 2 randomized controlled trials versus naproxen.

OBJECTIVE: Two studies evaluated efficacy and safety of tanezumab versus naproxen for treatment of knee or hip osteoarthritis (OA). METHODS: Randomized controlled studies [NCT00830063 (Study 1015, n=828) and NCT00863304 (Study 1018, n=840)] of subjects with hip or knee OA compared intravenous tanezumab (5 mg or 10 mg) to placebo and naproxen (500 mg twice daily). Coprimary outcomes were Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain, WOMAC Physical Function (0-10 numerical rating scale), and patient's global assessment of OA at Week 16. RESULTS: In both studies, tanezumab reduced pain versus placebo [least squares mean differences, 95% CI, tanezumab 5 mg: -1.21 (-1.72, -0.70); -1.13 (-1.65, -0.62); tanezumab 10 mg: -0.91 (-1.42, -0.40); -0.80 (-1.32, -0.29)], and improved function and global scores. Tanezumab 5 mg produced greater pain reduction [-0.76 (-1.28, -0.25); -0.69 (-1.21, -0.17)], and favorable functional and global outcomes versus naproxen. Pain reductions with tanezumab 10 mg versus naproxen did not reach significance, unlike functional (both studies) and global (1 study) outcomes; thus, tanezumab 10 mg was not superior to naproxen, and predefined statistical testing procedures were not met, allowing for conclusion of superiority of tanezumab 5 mg over naproxen despite replicated favorable coprimary outcomes. Tanezumab was associated with greater incidence of peripheral sensory adverse events (paresthesia, hyperesthesia, hypoesthesia, burning sensation), pain in extremity, peripheral edema, and arthralgia. Overall frequency and discontinuations as a result of adverse events were similar to placebo and naproxen. CONCLUSION: Tanezumab provides efficacious treatment of knee or hip OA and may have therapeutic utility in patients with OA who experience inadequate analgesia with nonsteroidal antiinflammatory drugs.

Long-term safety and effectiveness of tanezumab as treatment for chronic low back pain.

A noncontrolled, randomized, multicenter study (NCT00924664) evaluated long-term safety and effectiveness of tanezumab in patients with chronic low back pain following a randomized placebo- and active-controlled parent study that evaluated analgesic efficacy. Patients were randomized to tanezumab 10mg (n=321) or 20mg (n=527) administered at 8-week intervals via 3 intravenous injections followed by 4 subcutaneous injections. Effectiveness analyses included change from parent study baseline in Brief Pain Inventory Short Form, Roland Morris Disability Questionnaire, and Patient's Global Assessment of low back pain. Safety assessments included adverse event documentation, physical/neurological examinations, and laboratory tests. Mean treatment duration during the extension study was 194 and 202 days with tanezumab 10 and 20mg, respectively. Both tanezumab doses provided similar and sustained improvements in all effectiveness outcomes. The most frequently reported adverse events were arthralgia, paresthesia, and hypoesthesia. Adverse events initially described as osteonecrosis were reported in 6 patients (tanezumab 10mg, n=2; tanezumab 20mg, n=4); 9 additional patients (tanezumab 10mg, n=7; tanezumab 20mg, n=2) underwent total joint replacement (TJR). A blinded, independent adjudication committee reviewed all 6 patients with reported osteonecrosis and 4 of the 9 patients undergoing TJR. Adjudication outcomes were osteonecrosis (n=0), worsening osteoarthritis (n=5; 1 rapidly progressive), and another diagnosis or indeterminate (n=5). Tanezumab 10mg had better tolerability than tanezumab 20mg, and may represent an effective long-term treatment for chronic low back pain.

Efficacy and safety of tanezumab versus naproxen in the treatment of chronic low back pain.

Tanezumab is a humanized monoclonal antibody that specifically inhibits nerve growth factor as a treatment for chronic pain. This phase IIB study investigated the efficacy and safety of tanezumab for chronic low back pain vs placebo and naproxen. Patients (N=1347) received intravenous tanezumab (5, 10, or 20mg every 8weeks), naproxen (500mg twice daily), or placebo. The primary efficacy end point was mean change in daily average low back pain intensity (LBPI) from baseline to week 16. Secondary end points included mean change from baseline to week 16 in the Roland Morris Disability Questionnaire and Patient's Global Assessment (PGA) of low back pain. Tanezumab 10 and 20mg had similar efficacy profiles and significantly improved LBPI, Roland Morris Disability Questionnaire, and PGA scores vs both placebo and naproxen (P⩽.05). Tanezumab 5mg provided improvement of PGA scores vs placebo (P⩽.05), and naproxen resulted in significant improvement of LBPI vs placebo (P⩽.05). Adverse event incidence was comparable across tanezumab doses but higher than with placebo or naproxen. Arthralgia, pain in extremity, headache, and paresthesia were the most commonly reported adverse events by tanezumab-treated patients. The most frequently reported adverse events resulting in discontinuation of tanezumab treatment were arthralgia and paresthesia; the highest frequency was observed with tanezumab 20mg (both 1.4%). Serious adverse event incidence was similar across treatments. In conclusion, tanezumab provided significantly greater improvement in pain, function, and global scores vs placebo and naproxen in patients with chronic low back pain.

Comparison of the efficacy and safety of dual-opioid treatment with morphine plus oxycodone versus oxycodone/acetaminophen for moderate to severe acute pain after total knee arthroplasty.

BACKGROUND: In acute pain models, coadministration of low doses of morphine and oxycodone markedly enhanced analgesia relative to either opioid given alone. Enhanced analgesia with coadministration of morphine and oxycodone has also been reported in acute and chronic moderate to severe pain conditions during double-blind studies. OBJECTIVE: The goal of this study was to compare the efficacy and tolerability of a flexible dose regimen of the morphine/oxycodone combination versus oxycodone/acetaminophen and fixed low-dose morphine/oxycodone. METHODS: This was a 5-center, randomized, open-label study of hospitalized patients (n = 44) with acute moderate to severe postoperative pain after total knee arthroplasty. Inpatients were randomized to a flexible dose regimen of morphine/oxycodone (3 mg/2 mg to 24 mg/16 mg), fixed low-dose morphine/oxycodone regimen (3 mg/2 mg), or oxycodone/acetaminophen (5 mg/325 mg). Treatment was initiated following surgery after intravenous (IV) morphine patient-controlled analgesia. An algorithm was evaluated for converting the patient-controlled analgesia morphine dose to an initial oral dose of morphine/oxycodone. The primary efficacy variable was the time-weighted sum of pain intensity difference from 0 to 48 hours. RESULTS: The median values for the sum of the pain intensity difference from 0 to 48 hours for the morphine/oxycodone flexible dose and oxycodone/acetaminophen were similar and approximately twice that of fixed morphine/oxycodone 3 mg/2 mg (148.0, 139.5, and 71.3, respectively). Moderate to severe gastrointestinal adverse events occurred in 50% of patients in the oxycodone/acetaminophen group compared with 15% of the equianalgesic morphine/oxycodone group. On several items of the Brief Pain Inventory (general activity, walking ability, and sleep), the morphine/oxycodone flexible dose produced greater benefit than oxycodone/acetaminophen. CONCLUSIONS: Flexible dose morphine/oxycodone was superior to low-dose morphine/oxycodone and comparable to oxycodone/acetaminophen. Flexible dose morphine/oxycodone-treated patients had a lower rate of moderate to severe nausea or vomiting than equianalgesic oxycodone/acetaminophen-treated patients. Thus, morphine/oxycodone offers an attractive alternative to oxycodone/acetaminophen for the management of moderate to severe postoperative pain.

A multiple-day regimen of parecoxib sodium 20 mg twice daily provides pain relief after total hip arthroplasty.

BACKGROUND: This multicenter, multiple-dose, randomized, double-blind, parallel-group study compared the analgesic efficacy and safety of two dosing regimens of parecoxib sodium (parecoxib) versus placebo after total hip arthroplasty. METHODS: On study Day 1, 490 patients received a postoperative initial loading dose of IV parecoxib 40 mg, followed by a re-dose of parecoxib 20 mg in 484 of 490 patients. Subsequently, 479 randomized patients received double-blind treatment with parecoxib 20 mg bid (n = 159), parecoxib 20 mg qd (n = 159) followed by placebo, or placebo (n = 161) on Day 2. RESULTS: Patients treated with parecoxib 20 mg bid reported significantly lower summed pain intensity over 24 h (SPI-24) scores and improved patients' global evaluation of study medication (PGESM) ratings compared with placebo-treated patients on Days 2 to 5 (P < 0.05). For patients treated with parecoxib 20 mg qd, SPI-24 scores were significantly lower on Days 3 and 4 (P < 0.05), and PGESM ratings significantly improved on Day 5 compared with placebo. The incidence of adverse events was similar in all treatment groups with the exception of fever, vomiting and impaired concentration, which were significantly more common in the placebo group compared with one or other of the parecoxib treatment groups (P < 0.05). CONCLUSION: Multiple-day administration of parecoxib 20 mg once or twice daily is effective and generally well tolerated after total hip arthroplasty.

Oxymorphone: a mature molecule with new life.

The undertreatment of acute and chronic pain continues to be a significant health concern in the U.S. Opioids are recommended for the treatment of acute or chronic pain of moderate to severe intensity that is not responsive to other pharmacologic agents, such as nonsteroidal antiinflammatory drugs. A high level of interindividual responses to the analgesic effects and side effects of opioids necessitates the availability of multiple treatment options. Extended-release and immediate-release oral formulations of oxymorphone hydrochloride were recently approved by the U.S. Food and Drug Administration and may provide new options for patients who have not achieved adequate and well-tolerated analgesia with their current opioid. This review provides an overview of the basic pharmacology (including pharmacokinetic and pharmacodynamic profiles), clinical efficacy and tolerability of both oral oxymorphone formulations.

Efficacy and tolerability of oxymorphone immediate release for acute postoperative pain after abdominal surgery: a randomized, double-blind, active- and placebo-controlled, parallel-group trial.

BACKGROUND: Patients are typically switched from parenteral opioids to oral opioids during the 24 to 48 hours after surgery. In June 2006, an oral immediate-release (IR) tablet formulation of oxymorphone was approved for the treatment of acute moderate to severe pain. Single doses of oxymorphone IR have been reported to provide significant pain relief after orthopedic surgery. OBJECTIVE: This study assessed the efficacy and tolerability of multiple fixed doses of oxymorphone IR in the treatment of acute postoperative pain after abdominal surgery. METHODS: This was a multicenter, randomized, double-blind, active- and placebo-controlled, parallel-group study in men and women aged >or=18 years undergoing abdominal surgery that required a >or=3-cm incision. Patients who discontinued short-acting parenteral opioids and developed moderate or severe pain (4-point categorical scale [none, mild, moderate, or severe] and pain intensity >or=50 mm on a 100-mm visual analog scale [from 0 = no pain to 100 = worst pain imaginable]) within 30 hours after abdominal surgery were randomized to receive oxymorphone IR 10 or 20 mg, oxycodone IR 15 mg, or placebo every 4 to 6 hours after the previous dose. The study included 2 efficacy assessments: a single-dose evaluation for up to 6 hours after the dose, and a multipledose evaluation for up to 48 hours after the first dose. Pain was assessed at 15-minute intervals during the hour after the first dose, hourly thereafter for the next 5 hours, and before each subsequent dose. The primary efficacy end point was the median time to study discontinuation for all causes. Assessment of tolerability was based on the proportion of study discontinuations due to treatment-emergent adverse events (AEs). RESULTS: Three hundred thirty-one patients were included in the study. Demographic characteristics were similar across all groups: 98.8% (327) of patients were women, and 80.1% (265) of the abdominal surgeries were hysterectomies. The mean (SD) age of the study population was 42.6 (9.3) years. The median time to study discontinuation for all causes was significantly longer for all active treatments compared with placebo (oxymorphone IR 10 mg, 17.9 hours; oxymorphone IR 20 mg, 20.3 hours; oxycodone IR 15 mg, 24.1 hours; placebo, 4.8 hours; P < 0.006). Oxymorphone IR 20 mg was significantly more effective than placebo over the 6-hour single-dose evaluation (P < 0.05). With multiple dosing, all active-treatment groups had significantly lower least squares mean current and average pain intensities compared with placebo (P < 0.004 and P < 0.005, respectively). The least squares means of the average pain intensity were significantly lower among patients treated with oxymorphone IR 10 mg, oxymorphone IR 20 mg, or oxycodone IR 15 mg compared with those who received placebo (39.7, 35.2, 39.8, and 50.1, respectively; P < 0.005). Discontinuations due to treatment-emergent AEs did not differ significantly between groups: 8.5% (7/82), 17.3% (14/81), 13.3% (11/83), and 12.9% (11/85) in the oxymorphone IR 10-mg, oxymorphone IR 20-mg, oxycodone IR 15-mg, and placebo groups, respectively. The proportions of patients reporting at least 1 treatment-emergent AE were 46.3% (38/82), 51.9% (42/81), and 54.2% (45/83) in the oxymorphone IR 10-mg, oxymorphone IR 20-mg, and oxycodone IR 15-mg groups, respectively, compared with 34.1% (29/85) in the placebo group (P = NS). The fixed-dose design was a study limitation, as it did not allow titration to effect and thus did not mirror clinical practice. CONCLUSION: In this predominantly female population undergoing abdominal surgery, oxymorphone IR given every 4 to 6 hours for up to 48 hours provided efficacious and tolerable analgesia for moderate to severe pain.

Efficacy and safety of oxymorphone immediate release for the treatment of mild to moderate pain after ambulatory orthopedic surgery: results of a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To assess the analgesic efficacy and safety of 5 mg of oxymorphone immediate release (IR) for mild to moderate pain. DESIGN: Multicenter, double-blind, randomized, placebo-controlled study. SETTING: Ambulatory surgical centers. PARTICIPANTS: Outpatients (age, > or = 18 y) undergoing knee arthroscopy. INTERVENTION: Randomization to 5 mg of oxymorphone IR or placebo hourly as needed for up to 8 hours. MAIN OUTCOME MEASURE: Sum of pain intensity difference (SPID) from baseline to 8 hours. RESULTS: Among 122 patients randomized, 70.5% and 28.7% had moderate or mild postsurgical pain at baseline, respectively. The mean SPID score was significantly greater in the oxymorphone IR group, showing greater pain relief, compared with the placebo group (least squares mean difference +/- standard error, 76.9+/-28.09; 95% confidence interval, 21.26-132.59; P=.007). More placebo patients (48.4%) required rescue medication than oxymorphone IR patients (16.7%), with median times to use of rescue medication of 6 hours 54 minutes and more than 8 hours, respectively (P<.001). More patients (47.4%) rated oxymorphone IR "very good" or "excellent" for pain relief versus placebo (25.0%). No oxymorphone IR-treated patients discontinued because of adverse events (AEs) or experienced serious AEs. CONCLUSIONS: Five milligrams of oxymorphone IR was well tolerated and effective at relieving mild or moderate postsurgical pain after outpatient knee surgery.

Controlled-release oxycodone for pain in diabetic neuropathy: a randomized controlled trial.

BACKGROUND AND OBJECTIVE: Opioid treatment has played a limited role in the management of diabetic neuropathy, in part because of concerns about the responsiveness of neuropathic pain to opioid treatment. This controlled study evaluated the efficacy and safety of controlled-release (CR) oxycodone in subjects with moderate to severe pain due to diabetic neuropathy. METHODS: This multicenter, randomized, double-blind, placebo-controlled, parallel-group study included 159 subjects with moderate to severe pain due to diabetic neuropathy. Treatment began with either one 10-mg tablet of CR oxycodone (n = 82) or identical placebo (n = 77) every 12 hours. Doses could be increased every 3 days to a maximum of 6 tablets (60 mg CR oxycodone) every 12 hours. Treatment lasted up to 6 weeks. The primary efficacy variable was overall average daily pain intensity during study days 28 to 42. RESULTS: At an average (SD) dose of 37 (21) mg per day (range 10 to 99 mg/d), CR oxycodone provided more analgesia than placebo (p= 0.002) in the intent-to-treat cohort. From days 28 to 42, overall average daily pain intensity (least squares mean +/-SE), rated in subject diaries on a numeric scale of 0 (no pain) to 10 (pain as bad as you can imagine), was 4.1 +/- 0.3 in subjects given CR oxycodone and 5.3 +/- 0.3 in placebo-treated subjects. Overall, 80 (96%) of 82 subjects given CR oxycodone and 52 (68%) of 77 subjects who received placebo reported adverse events. The most common adverse events in the CR oxycodone group were opioid related. CONCLUSIONS: In this 6-week trial, CR oxycodone was effective for the treatment of moderate to severe pain due to diabetic neuropathy. Adverse events were typical of opioid-related side effects.