Clinical evaluation of PF614, a novel TAAP prodrug of oxycodone, versus OxyContin in a multi-ascending dose study with a bioequivalence arm in healthy volunteers.

PF614, a trypsin-activated abuse protection oxycodone prodrug designed to reduce recreational drug abuse, was compared to OxyContin for safety and pharmacokinetics (PKs) of plasma oxycodone following oral administration. This study was a two-part design including a multi-ascending dose (part A) and a bioequivalence (BE) study (part B) in healthy volunteers. In part A, 24 subjects were randomized 3:1 to receive PF614 (50, 100, or 200 mg, n = 6/cohort) or OxyContin (20, 40, or 80 mg; n = 2/cohort) in ascending cohorts, delivered every 12 h for a total of nine doses. In part B, 60 subjects randomized in a four-way crossover to evaluate BE, received PF614 100 mg and OxyContin 40 mg in fasted and fed (high-fat diet) states. All subjects were naltrexone blocked prior to first study drug administration to protect against opioid-related adverse effects; repeat doses were provided on days 1-5. In part A, PF614 was well-tolerated following twice daily doses of up to 200 mg for 5 days. Plasma oxycodone maximal plasma concentration and area under the concentration time curve increased linearly with increasing doses. Part B showed that plasma oxycodone BE was achieved following 100 mg PF614 or 40 mg OxyContin under both fasted and fed conditions. Additionally, PF614 provided similar oxycodone exposures following both fasted and fed states. This study confirms findings from our single-ascending dose study, showing that PF614 100 mg releases oxycodone with a PK profile comparable to 40 mg OxyContin under both fasted and fed conditions and with a similar safety profile under naltrexone-blocked conditions.

A Randomized Controlled Trial of a Novel Formulation of Ketorolac Tromethamine for Continuous Infusion (NTM-001) in Healthy Volunteers.

INTRODUCTION: There is an urgent unmet medical need for a safe, effective, nonopioid analgesic agent for postoperative pain control. METHODS: This first-in-man study was designed to explore a data-informed, model-based candidate dosage regimen and safety of a novel formulation of ketorolac tromethamine (NTM-001) delivered as a 12.5-mg intravenous (IV) bolus followed immediately by 3.5 mg/h continuous infusion over 24 h compared versus IV bolus dosing of 30 mg generic ketorolac every 6 h. The study evaluated pharmacokinetic parameters and safety profiles based on a targeted product profile. A graphical overlay method and model-based comparisons were used to assess the concentration-time curve. RESULTS: Healthy adults (n = 28, 50% men) received NTM-001 and bolus dosing in an open-label crossover design. Observed plasma concentrations were tightly aligned with predicted values with no outliers. Graphical overlay comparisons showed low between-subject variability and agreed with forecasted concentration-time targets. The pharmacokinetic (PK) base models fit with preliminary PK data from both the NTM-001 and bolus groups with model fit median profiles within 95% prediction limits and no updating of the models. Consistent with serum concentration-time profiles, pain relief scores fell within predicted limits, with initial pain relief scores of NTM-001 slightly above the target profile, likely because the initial serum ketorolac concentrations were somewhat higher than predicted. The 24-h pain relief predicted for NTM-001 based on the area under the median ketorolac pain relief versus time curve was about 6% below that of the pain relief target. Both treatments were well tolerated and no subject withdrew because of adverse events. CONCLUSIONS: The PK parameters for NTM-001 and comparator bolus were similar to the modeling targets with no updating of the base model. There were no outliers and little intersubject variability. NTM-001 delivered as a bolus of 12.5 mg IV followed immediately by continuous infusion of 3.5 mg/h using a standard hospital infusion pump may offer an alternative to opioids for acute postoperative pain control.

Opioids are effective analgesics but the risk for opioid use disorder (OUD) and opioid-associated side effects limit their use even for postoperative pain. Ketorolac is an established nonopioid pain reliever that may be as efficacious as morphine in this setting. This study evaluated a new ketorolac product (NTM-001) compared to generic ketorolac. Both were delivered using a standard hospital intravenous (IV) drug pump. The new ketorolac product was administered first with a loading dose of 12.5 mg followed immediately by a continuous IV infusion of 3.5 mg/h. This was compared to IV generic ketorolac administered as a bolus dose of 30 mg every 6 h. The study enrolled 28 healthy adult volunteers. As a crossover study, subjects underwent both treatments: once with the continuous infusion (NTM-001) and once with the IV injection every 6 h (bolus group) with a "washout" period in between. Blood was collected from the volunteers at several time-determined points during the 48-h study to chart ketorolac concentrations in the blood, which can be correlated to predicted levels of pain control. In this study, blood concentrations of ketorolac were reliably predictable and side effects were generally mild with no unexpected adverse events. The continuous infusion group achieved analgesic benefit at a lower total dose than did the every-6-h group over 24 h.

Movement to the Clinic of Soluble Epoxide Hydrolase Inhibitor EC5026 as an Analgesic for Neuropathic Pain and for Use as a Nonaddictive Opioid Alternative.

This report describes the development of an orally active analgesic that resolves inflammation and neuropathic pain without the addictive potential of opioids. EC5026 acts on the cytochrome P450 branch of the arachidonate cascade to stabilize epoxides of polyunsaturated fatty acids (EpFA), which are natural mediators that reduce pain, resolve inflammation, and maintain normal blood pressure. EC5026 is a slow-tight binding transition-state mimic that inhibits the soluble epoxide hydrolase (sEH) at picomolar concentrations. The sEH rapidly degrades EpFA; thus, inhibiting sEH increases EpFA in vivo and confers beneficial effects. This mechanism addresses disease states by shifting endoplasmic reticulum stress from promoting cellular senescence and inflammation toward cell survival and homeostasis. We describe the synthesis and optimization of EC5026 and its development through human Phase 1a trials with no drug-related adverse events. Additionally, we outline fundamental work leading to discovery of the analgesic and inflammation-resolving CYP450 branch of the arachidonate cascade.

Preclinical Assessment of the Analgesic Pharmacology of NKTR-181 in Rodents.

OBJECTIVE: Pharmacological evaluation of the mu-opioid receptor (MOR) agonist properties of NKTR-181 in rodent models. METHODS: Graded noxious stimulus intensities were used in rats to establish the antinociceptive potency and efficacy of NKTR-181 relative to morphine, fentanyl, and oxycodone. Characteristics of MOR agonist actions, as measured by antinociceptive tolerance and cross-tolerance, as well as opioid-induced hyperalgesia (OIH) and naloxone-precipitated withdrawal in NKTR-181- and morphine-dependent in mice, were compared. RESULTS: NKTR-181 showed dose- and time-related antinociception with similar maximal effects to morphine in the rat and mouse hot-water tail-flick test. No sex or species differences were observed in NKTR-181 or morphine antinociception. Rats treated with NKTR-181 and morphine exhibited decreases in both potency and maximal efficacy as nociceptive stimulus intensity was increased from a water temperature of 50 °C to 54 °C. Evaluation of antinociception at a high stimulus intensity revealed that oxycodone and fentanyl exhibited greater efficacy than either NKTR-181 or morphine. The relative potency difference between NKTR-181 and morphine across all tail-flick studies was determined to be 7.6-fold (90% confidence interval, 2.6, 21.5). The peak antinociceptive effect of NKTR-181 was delayed compared to that of the other opioids and cumulative drug effects were not observed. Repeated treatment with escalating, approximately equi-analgesic doses of NKTR-181 or morphine, produced antinociceptive tolerance and cross-tolerance. Under these pharmacological conditions, OIH and naloxone-precipitated physical dependence were similar for NKTR-181 and morphine. CONCLUSIONS: NKTR-181 had a slower onset, but similar efficacy, to morphine in the models studied supporting reduced abuse potential while maintaining analgesic effect in comparison with current opioids.

Dilemma of Addiction and Respiratory Depression in the Treatment of Pain: A Prototypical Endomorphin as a New Approach.

OBJECTIVE: Although mu-opioid receptor agonists have been the mainstay of analgesic regimens for moderate to severe pain, they are associated with serious side effects, risks, and limitations. We evaluate the most serious risks associated with conventional opioids and compare these with the pharmacology of CYT-1010, a prototypical endomorphin and mu-opioid receptor agonist. RESULTS: Addiction and respiratory depression are serious risks of traditional mu-opioid analgesics. Mitigation strategies have been inadequate at addressing the opioid crisis and may interfere with the effective treatment of pain. Improved understanding of mu-opioid receptor biology and the discovery in 1997 of an additional and unique family of endogenous opioid peptides (endomorphins) have provided a pathway for dissociating analgesia from opioid-related adverse events and developing new classes of mu-opioid receptor agonists that use biased signaling and/or target novel sites to produce analgesia with reduced side effect liability. Endomorphin-1 and -2 are endogenous opioid peptides highly selective for mu-opioid receptors that exhibit potent analgesia with reduced side effects. CYT-1010 is a cyclized, D-lysine-containing analog of endomorphin-1 with a novel mechanism of action targeting traditional mu- and exon 11/truncated mu-opioid receptor 6TM variants. CYT-1010 preclinical data have demonstrated reduced abuse potential and analgesic potency exceeding that of morphine. In an initial phase 1 clinical study, CYT-1010 demonstrated significant analgesia vs baseline and no respiratory depression at the dose levels tested. CONCLUSIONS: CYT-1010 and other novel mu-opioid receptor agonists in clinical development are promising alternatives to conventional opioids that may offer the possibility of safer treatment of moderate to severe pain.

Pharmaceutical Effects of Inhibiting the Soluble Epoxide Hydrolase in Canine Osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease that causes pain and bone deterioration driven by an increase in prostaglandins (PGs) and inflammatory cytokines. Current treatments focus on inhibiting prostaglandin production, a pro-inflammatory lipid metabolite, with NSAID drugs; however, other lipid signaling targets could provide safer and more effective treatment strategies. Epoxides of polyunsaturated fatty acids (PUFAs) are anti-inflammatory lipid mediators that are rapidly metabolized by the soluble epoxide hydrolase (sEH) into corresponding vicinal diols. Interestingly, diol levels are increased in the synovial fluid of humans with OA, warranting further research on the biological role of this lipid pathway in the progression of OA. sEH inhibitors (sEHI) stabilize these biologically active, anti-inflammatory lipid epoxides, resulting in analgesia in both neuropathic, and inflammatory pain conditions. Most experimental studies testing the analgesic effects of sEH inhibitors have used experimental rodent models, which do not completely represent the complex etiology of painful diseases. Here, we tested the efficacy of sEHI in aged dogs with natural arthritis to provide a better representation of the clinical manifestations of pain. Two sEHI were administered orally, once daily for 5 days to dogs with naturally occurring arthritis to assess efficacy and pharmacokinetics. Blinded technicians recorded the behavior of the arthritic dogs based on pre-determined criteria to assess pain and function. After 5 days, EC1728 significantly reduced pain at a dose of 5 mg/kg compared to vehicle controls. Pharmacokinetic evaluation showed concentrations exceeding the enzyme potency in both plasma and synovial fluid. In vitro data showed that epoxyeicosatrienoic acid (EETs), epoxide metabolites of arachidonic acid, decreased inflammatory cytokines, IL-6 and TNF-α, and reduced cytotoxicity in canine chondrocytes challenged with IL1ß to simulate an arthritic environment. These results provide the first example of altering lipid epoxides as a therapeutic target for OA potentially acting by protecting chondrocytes from inflammatory induced cytotoxicity. Considering the challenges and high variability of naturally occurring disease in aged dogs, these data provide initial proof of concept justification that inhibiting the sEH is a non-NSAID, non-opioid, disease altering strategy for treating OA, and warrants further investigation.

Soluble epoxide hydrolase as a therapeutic target for pain, inflammatory and neurodegenerative diseases.

Eicosanoids are biologically active lipid signaling molecules derived from polyunsaturated fatty acids. Many of the actions of eicosanoid metabolites formed by cyclooxygenase and lipoxygenase enzymes have been characterized, however, the epoxy-fatty acids (EpFAs) formed by cytochrome P450 enzymes are newly described by comparison. The EpFA metabolites modulate a diverse set of physiologic functions that include inflammation and nociception among others. Regulation of EpFAs occurs primarily via release, biosynthesis and enzymatic transformation by the soluble epoxide hydrolase (sEH). Targeting sEH with small molecule inhibitors has enabled observation of the biological activity of the EpFAs in vivo in animal models, greatly contributing to the overall understanding of their role in the inflammatory response. Their role in modulating inflammation has been demonstrated in disease models including cardiovascular pathology and inflammatory pain, but extends to neuroinflammation and neuroinflammatory disease. Moreover, while EpFAs demonstrate activity against inflammatory pain, interestingly, this action extends to blocking chronic neuropathic pain as well. This review outlines the role of modulating sEH and the biological action of EpFAs in models of pain and inflammatory diseases.

In vitro and in vivo assessment of the abuse potential of PF614, a novel BIO-MD™ prodrug of oxycodone.

OBJECTIVE: The need for pain medication which will not lead to abuse is well recognized. Ensysce has designed prodrug analogs of the commonly used pain medications including hydromorphone, oxycodone (OC), hydrocodone, and morphine that limit their use to oral delivery, two of which are in clinical development. This study was undertaken to demonstrate that PF614, an extended-release prodrug of OC, allows the release of OC as designed when delivered orally, yet it resists ex vivo extraction with household chemicals and is pharmacologically inactive when administered by nonoral routes (nasal and parenteral), thereby substantially reducing its intravenous (IV) and intranasal abuse potential. METHODS: In vitro and in vivo methods were used to determine release of OC from PF614 and to show potential µ-opioid receptor activity. Plasma and cerebral spinal fluid levels of OC were evaluated following in vivo IV administration of PF614 in rats. In vitro extraction of OC from PF614 was explored using enzymes, common solvents, and household chemicals at room temperature and elevated temperature over time to determine release of OC from the prodrug. RESULTS: PF614 was stable with in vitro exposure to human plasma, saliva, and liver microsomes or culinary enzyme preparations. PF614 was stable (≥90 percent remaining as intact prodrug) under all room temperature conditions evaluated for 24 hours. At 80°C for 1 hour, no OC was released. Incubation at 80°C for 24 hours in vinegar or vodka produced a conversion to OC of 6 percent. Incubation with trypsin at 37°C converted PF614 approximately stoichiometric to OC with half-life of 4 hours. PF614's penetration of the central nervous system was 83-fold lower than OC and it had a 6.5-fold reduced potency as a µ-opioid agonist. Finally, oral PF614 delivers OC into plasma with an extended-release profile in dogs (reduced Cmax; delayed Tmax). CONCLUSIONS: The Bio-Activated Molecular Delivery prodrug design limits the use of PF614 to the intended oral route of delivery with reduced potential for IV or nasal abuse, as it cannot be activated intravenously or nasally to provide an active opioid. Unlike existing opioid formulations, the extended-release profile of PF614 cannot be accelerated by chewing or ex vivo extraction to pharmacologically active substances.

A randomized, double-blind, placebo-controlled trial of injected capsaicin for pain in Morton's neuroma.

Intermetatarsal neuroma or Morton's neuroma is a painful condition of the foot resulting from an entrapment of the common digital nerve typically in the third intermetatarsal space. The pain can be severe and especially problematic with walking. Treatment options are limited and surgery may lead to permanent numbness in the toes. Capsaicin, the pungent ingredient of hot peppers, produces analgesia by inducing retraction of nociceptive afferents from the area of innervation and is effective in treating certain neuropathic pain disorders. A randomized double-blind placebo-controlled study was conducted to test the efficacy, tolerability, and safety of a single 0.1 mg dose of capsaicin vs placebo injected into the region of the neuroma. A total of 58 subjects diagnosed with Morton's neuroma with foot pain ≥4 (0-10 numerical pain rating scale) were injected with 2 mL of lidocaine into the intermetatarsal space proximal to the neuroma to provide local anesthesia. After 5 minutes, 0.1 mg capsaicin or placebo was injected into the intermetatarsal space containing the painful neuroma. Average foot pain was rated for 2 weeks before through 4 weeks after injection. At weeks 1 and 4, the decrease in pain was significantly greater in the subjects treated with capsaicin (P = 0.021 and P = 0.019, respectively). A trend toward significance was noted at weeks 2 and 3. Improvements in functional interference scores and reductions in oral analgesic use were also seen in the capsaicin-treated group. These findings suggest that injection of capsaicin is an efficacious treatment option for patients with painful intermetatarsal neuroma.

An open-label pilot study of pulsed electromagnetic field therapy in the treatment of failed back surgery syndrome pain.

Persistent pain following back surgery remains a major treatment challenge. The primary objective of this open-label exploratory study was to investigate the analgesic effectiveness of pulsed electromagnetic field therapy administered twice daily over a 45-day period in 34 subjects (68% female) with persistent or recurrent pain following back surgery. A secondary goal was to guide the design of future randomized controlled trials that could target responsive subpopulations. All predefined primary and secondary outcomes, including change in pain intensity (PI), physical function (Oswestry Disability Index), analgesic consumption, and overall well-being (Patient Global Impression of Change), are reported. A responder analysis (≥30% reduction in PI versus baseline) was added as a post hoc evaluation. Safety outcomes, as well as results of a cost-avoidance survey, are also summarized. Of the 30 per-protocol subjects who completed the study, 33% reported a clinically meaningful (≥30%) reduction in PI. A higher response rate (60%) was reported for subjects who had undergone discectomy prior to the trial compared to subjects who had undergone other types of surgical interventions (decompression or fusion) without discectomy. Improvements in PI were paralleled by improvements in secondary outcomes. Relative to baseline, responders reported an average 44% and 55% reduction in back PI and leg PI (respectively), and an average 13% improvement in Oswestry Disability Index scores. In the per-protocol population, 50% of responders and 12% of nonresponders reported less analgesia consumption at the end of treatment versus baseline. Sixty-seven percent of per-protocol responders and 0% of nonresponders reported clinically meaningful improvement in overall well-being on the Patient Global Impression of Change scale.

Single intrathecal administration of the transcription factor decoy AYX1 prevents acute and chronic pain after incisional, inflammatory, or neuropathic injury.

The persistence of pain after surgery increases the recovery interval from surgery to a normal quality of life. AYX1 is a DNA-decoy drug candidate designed to prevent post-surgical pain following a single intrathecal injection. Tissue injury causes a transient activation of the transcription factor EGR1 in the dorsal root ganglia-dorsal horn network, which then triggers changes in gene expression that induce neuronal hypersensitivity. AYX1 is a potent, specific inhibitor of EGR1 activity that mimics the genomic EGR1-binding sequence. Administered in the peri-operative period, AYX1 dose dependently prevents mechanical hypersensitivity in models of acute incisional (plantar), inflammatory (CFA), and chronic neuropathic pain (SNI) in rats. Furthermore, in a knee surgery model evaluating functional measures of postoperative pain, AYX1 improved weight-bearing incapacitance and spontaneous rearing compared to control. These data illustrate the potential clinical therapeutic benefits of AYX1 for preventing the transition of acute to chronic post-surgical pain.

Randomized control trial of topical clonidine for treatment of painful diabetic neuropathy.

A length-dependent neuropathy with pain in the feet is a common complication of diabetes (painful diabetic neuropathy). It was hypothesized that pain may arise from sensitized-hyperactive cutaneous nociceptors, and that this abnormal signaling may be reduced by topical administration of the α(2)-adrenergic agonist, clonidine, to the painful area. This was a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial. Nociceptor function was measured by determining the painfulness of 0.1% topical capsaicin applied to the pretibial area of each subject for 30minutes during screening. Subjects were then randomized to receive 0.1% topical clonidine gel (n=89) or placebo gel (n=90) applied 3 times a day to their feet for 12weeks. The difference in foot pain at week 12 in relation to baseline, rated on a 0-10 numerical pain rating scale (NPRS), was compared between groups. Baseline NPRS was imputed for missing data for subjects who terminated the study early. The subjects treated with clonidine showed a trend toward decreased foot pain compared to the placebo-treated group (the primary endpoint; P=0.07). In subjects who felt any level of pain to capsaicin, clonidine was superior to placebo (P<0.05). In subjects with a capsaicin pain rating ⩾2 (0-10, NPRS), the mean decrease in foot pain was 2.6 for active compared to 1.4 for placebo (P=0.01). Topical clonidine gel significantly reduces the level of foot pain in painful diabetic neuropathy subjects with functional (and possibly sensitized) nociceptors in the affected skin as revealed by testing with topical capsaicin. Screening for cutaneous nociceptor function may help distinguish candidates for topical therapy for neuropathic pain.

Evaluating therapeutic benefit in postsurgical analgesia requires global assessment: an example from liposome bupivacaine in hemorrhoidectomy.

BACKGROUND AND OBJECTIVE: Interpreting analgesic efficacy based solely on measures of pain intensity can be misleading. Here, we use data from an adult hemorrhoidectomy study to demonstrate the importance of evaluating pain intensity scores with other outcome measures in interpreting analgesic study results. METHODOLOGY: We looked for coordinated outcome measures including pain intensity at rest using a numeric rating scale (NRS), postsurgical consumption of rescue medication, subject-reported results from the Brief Pain Inventory, subject satisfaction with postsurgical analgesia, and adverse events. RESULTS: The analgesic efficacy of liposome bupivacaine was reflected in a significant reduction in pain intensity scores at each timed assessment during the first 12 to 24 hours after surgery (mean NRS at 12 hours: liposome bupivacaine, 2.2; placebo, 2.9; P = 0.04), and less consumption of opioid rescue medications thereafter through 72 hours postsurgery (mean total amount of opioids consumed: liposome bupivacaine, 10 mg; placebo, 18 mg; P = 0.0006). These observations are supported by results of other outcome measures, including time to first use of opioid rescue medication, pain-related interference of subject functionality, and subject satisfaction with postsurgical analgesia. CONCLUSION: Liposome bupivacaine produced superior analgesia when compared with placebo at early postoperative time points, but appropriate use of rescue medication diminished this effect after 12 hours. However, based on our assessment of multiple outcome measures used in the study, it appears that the therapeutic benefit associated with the tested analgesic lasted throughout the 72-hour study period.

Onset of action of diclofenac potassium liquid-filled capsules in dental surgery patients.

OBJECTIVE: Diclofenac potassium soft gelatin capsules (DPSGC) are a low-dose, liquid-filled formulation that uses patented dispersion technology to facilitate rapid and consistent gastrointestinal absorption. Onset of pain relief experienced by patients receiving DPSGC was evaluated in two dental pain studies. Confirmed perceptible pain relief was evaluated in a post hoc analysis from these randomized controlled trials. RESEARCH DESIGN AND METHODS: Adult patients (n = 514) were enrolled in two multicenter, parallel group, double-blind, placebo-controlled studies. Patients undergoing third molar extraction and experiencing a requisite level of pain (≥50 mm on a 100-mm visual analog scale within 4 hours post-surgery) were randomized to receive single doses of DPSGC 25 mg, 50 mg, 100 mg, or placebo. Pain was assessed at baseline and during 6 hours after dosing. Times to onset of perceptible and meaningful pain relief were recorded using the two-stopwatch method. Confirmed perceptible pain relief was determined in the DPSGC and placebo groups by calculating the median time to onset of perceptible pain relief (first stopwatch) in only those individuals who reported meaningful pain relief (second stopwatch). RESULTS: More than 80% of patients achieved confirmed perceptible pain relief in the DPSGC groups compared with less than 30% of patients in the placebo group (Study 1 and Study 2, p < 0.0001). The median time to onset of confirmed perceptible pain relief in the two studies was less than 30 minutes for patients receiving any dose of DPSGC and more than 360 minutes in the placebo group (Study 1 and Study 2, p < 0.0001). DPSGC was well tolerated and no serious adverse events were reported. Study design limitations include the short duration of the trial and evaluation of a relatively limited patient population. CONCLUSIONS: These results indicate that DPSGC was efficacious in providing a rapid onset of confirmed perceptible pain relief within 30 minutes of administration in these single dose postoperative dental pain studies.

Phase III trial of alvimopan, a novel, peripherally acting, mu opioid antagonist, for postoperative ileus after major abdominal surgery.

PURPOSE: Postoperative ileus presents significant clinical challenges that potentially prolong hospital stay, contribute to readmission, and increase morbidity. There is no approved treatment for postoperative ileus. Alvimopan is a novel, peripherally acting, mu opioid receptor antagonist currently in development for the management of postoperative ileus. METHODS: Patients undergoing partial colectomy or simple or radical hysterectomy were randomized to receive alvimopan 6 mg (n = 152), alvimopan 12 mg (n = 146), or placebo (n = 153) orally 2 hours before surgery and twice daily thereafter until discharge or for up to seven days. The primary efficacy end point, time to return of gastrointestinal function, was a composite measure of passage of flatus or stool and tolerating solid food. Secondary end points included time to the hospital discharge order written. Adverse events were monitored throughout the study. RESULTS: Mean time to gastrointestinal recovery was significantly reduced in patients treated with alvimopan 6 mg vs. placebo (hazard ratio = 1.45; P = 0.003), with a smaller reduction seen with alvimopan 12 mg (hazard ratio = 1.28; P = 0.059). Mean time to the hospital discharge order written was significantly accelerated in patients treated with alvimopan 6 mg (hazard ratio = 1.50; P < 0.001). The most common treatment-emergent adverse events across all treatment groups were nausea, vomiting, and hypotension; the incidence of nausea and vomiting was reduced by 53 percent in the alvimopan 12-mg group. CONCLUSIONS: In patients undergoing major abdominal surgery, alvimopan accelerated gastrointestinal recovery and time to the hospital discharge order written compared with placebo and was well tolerated.

Alvimopan: an oral, peripherally acting, mu-opioid receptor antagonist for the treatment of opioid-induced bowel dysfunction--a 21-day treatment-randomized clinical trial.

Alvimopan has been shown to reverse the inhibitory effect of opioids on gastrointestinal transit without affecting analgesia. We evaluated oral alvimopan, 0.5 or 1 mg, versus placebo, once daily for 21 days, in 168 patients with opioid-induced bowel dysfunction (OBD) who were receiving chronic opioid therapy (minimum, 1 month) for nonmalignant pain (n = 148) or opioid dependence (n = 20). The primary outcome was the proportion of patients having at least one bowel movement (BM) within 8 hours of study drug on each day during the 21-day treatment period. Averaged over the 21-day treatment period, 54%, 43%, and 29% of patients had a BM within 8 hours after alvimopan 1 mg, 0.5 mg, or placebo, respectively (P < .001). Secondary outcomes of median times to first BM were 3, 7, and 21 hours after initial doses of 1 mg, 0.5 mg, and placebo, respectively (P < .001; 1 mg vs placebo). Weekly BMs and overall patient satisfaction were increased after the 1-mg dose (P < .001 at weeks 1 and 2 vs placebo, and P = .046, respectively). Treatment-emergent adverse events were primarily bowel-related, occurred during the first week of treatment, and were of mild to moderate severity. Alvimopan was generally well tolerated and did not antagonize opioid analgesia. Patients treated with chronic opioid therapy often experience opioid-induced bowel dysfunction as a result of undesirable effects on peripheral opioid receptors located in the gastrointestinal tract. Alvimopan, a novel peripheral opioid mu-receptor antagonist, has demonstrated significant efficacy for the management of opioid-induced bowel dysfunction without compromise of centrally mediated opioid-induced analgesia.