Naltrexone Hydrochloride Extended Release Capsules Research Articles

A multicenter, primary-care-based, open-label study to assess the success of converting opioid-experienced patients with chronic moderate-to-severe pain to morphine sulfate and naltrexone hydrochloride extended-release capsules using a standardized conversion guide.

ObjectiveTo evaluate the conversion of opioid-experienced patients with chronic moderate-to-severe pain to extended-release morphine sulfate with sequestered naltrexone hydrochloride (MSN) using a standardized conversion guide.MethodsThis open-label, single-arm study was conducted in 157 primary care centers in the United States. A total of 684 opioid-experienced adults with chronic moderate-to-severe pain were converted to oral administration of MSN from transdermal fentanyl and oral formulations of hydrocodone, hydromorphone, methadone, oxycodone, oxymorphone, and other morphine products using a standardized conversion guide. The primary endpoint was the percentage of patients achieving a stable MSN dose within a 6-week titration phase. Secondary endpoints included duration of time to stable dose, number of titration steps, safety and efficacy measures, and investigator assessment of conversion guide utility.ResultsOf the 684 patients, 51.3% were converted to a stable dose of MSN (95% confidence interval: 47.5%, 55.1%). The mean (standard deviation) number of days to stable dose was 20 (8.94), and number of titration steps to stable dose was 2.4 (1.37). The majority of adverse events were mild/moderate and consistent with opioid therapy. Mean pain scores at stable dose decreased from baseline. Investigators were generally satisfied with the conversion guide and, in 94% of cases, reported they would use it again.ConclusionConversion to MSN treatment using the standardized MSN conversion guide was an attainable goal in approximately half of the population of opioid-experienced patients with chronic moderate-to-severe pain. Investigators found the guide to be a useful tool to assist conversion of opioid-experienced patients to MSN.

Opioid Antagonists

Opioid Antagonists

Assessment of Pharmacodynamic Effects Following Oral Administration of Crushed Morphine Sulfate and Naltrexone Hydrochloride Extended-Release Capsules Compared with Crushed Morphine Sulfate Controlled-Release Tablets and Placebo in Nondependent Recreational Opioid Users

To compare the pharmacodynamic effects, including self-reports of "drug liking" and "high," of crushed morphine sulfate and naltrexone hydrochloride extended-release capsules (MSN), crushed morphine sulfate controlled-release (CR) tablets, and placebo in an abuse potential study. Randomized, double-blind, placebo-controlled, three-way crossover study. Single-center. Nondependent recreational opioid users. Orally administered crushed MSN (120-mg morphine sulfate and 4.8-mg naltrexone hydrochloride), crushed 120-mg morphine sulfate CR, and placebo. Subjective ratings (100-point visual analog scales) of positive drug effects (drug liking, high, good effects, take drug again, and overall drug liking), any effects, and negative effects (bad effects, feel sick, nausea, sleepy, and dizzy), along with pupillometry, pharmacokinetic (PK), and safety assessments. Crushed morphine sulfate CR significantly increased ratings of all positive subjective measures relative to placebo (P < 0.0001). Crushed MSN significantly decreased all positive subjective ratings compared with morphine sulfate CR (P ≤ 0.005), but significantly increased ratings compared with placebo (P < 0.03). Peak pupil diameter was significantly larger for MSN than morphine sulfate (P < 0.0001). PK analysis of morphine plasma concentrations indicated that Cmax was significantly lower and tmax significantly longer for crushed MSN compared with crushed morphine sulfate CR. Plasma concentrations of naltrexone and 6-β-naltrexol were present following crushed MSN. This study demonstrated that when crushed and administered orally to nondependent recreational opioid users, MSN was associated with significantly lower scores on all positive subjective measures including drug liking and high, and significantly less pupil constriction compared with crushed morphine sulfate CR.

A multicenter, 12-month, open-label, single-arm, safety study of oxycodone hydrochloride and naltrexone hydrochloride extended-release capsules (ALO-02) in patients with moderate to severe chronic non-cancer pain

A multicenter, 12-month, open-label, single-arm, safety study of oxycodone hydrochloride and naltrexone hydrochloride extended-release capsules (ALO-02) in patients with moderate to severe chronic non-cancer pain

Effects of Alcohol on the Pharmacokinetics of Morphine Sulfate and Naltrexone Hydrochloride Extended Release Capsules

Although contraindicated, coingestion of alcohol and opioids by patients or drug abusers is a major health concern because of dangerous additive and potentially life-threatening sedative and respiratory effects. In addition, alcohol has been shown to disrupt the extended-release characteristics of certain extended-release opioid formulations, releasing a hazardous amount of opioid over a short time period. Morphine sulfate and naltrexone hydrochloride extended release capsules (MS-sNT), which contain naltrexone sequestered in each pellet core, are indicated for management of chronic, moderate to severe pain. Sequestered naltrexone is designed for release upon product tampering (crushing) to potentially mitigate morphine-induced subjective effects. This open-label, single-dose, 4-way crossover, pharmacokinetic drug interaction study compared the relative bioavailability of morphine and naltrexone when MS-sNT is administered (under fasting conditions) with increasing doses of alcohol. Thirty-two healthy, opioid-naive adults were randomized to MS-sNT administered with 240 mL of 4%, 20%, or 40% alcohol or water. No drug interaction was found between morphine in MS-sNT and 4% or 20% alcohol. Administration with 40% alcohol did not affect overall morphine exposure but was associated with a 2-fold increase in C(max) and reduction of t(max) from 9 to 4 hours versus MS-sNT taken with water. Naltrexone sequestering was successful in all treatment arms and not affected by coadministration with alcohol over the dose range tested.

Effects of concurrent intravenous morphine sulfate and naltrexone hydrochloride on end-tidal carbon dioxide

BackgroundRespiratory depression, a potentially fatal side-effect of opioid-overdose, may be reversed by timely administration of an opioid antagonist, such as naloxone or naltrexone. Tampering with a formulation of morphine sulfate and sequestered naltrexone hydrochloride extended release capsules (MS-sNT) releases both the opioid morphine and the antagonist naltrexone. A study in recreational opioid-users indicated that morphine and naltrexone injected in the 25:1 ratio (duplicating the ratio of the formulation) found MS-sNT reduced morphine-induced euphoric effects vs intravenous (IV) morphine alone. In the same study, the effects of morphine + naltrexone on end-tidal carbon dioxide (EtCO2), a measure of respiratory-depression, were evaluated and these data are reported here.MethodsSingle-center, placebo-controlled, double-blind crossover study. Non-dependent male opioid users were randomized to receive single IV doses of placebo, 30 mg morphine alone, and 30 mg morphine + 1.2 mg naltrexone. EtCO2 was measured by noninvasive capnography.ResultsSignificant differences in EtCO2 least-squares means across all treatments for maximal effect (Emax) and area under the effect curve (AUE0-2, AUE0-8, AUE0-24) were detected (all p ≤ 0.0011). EtCO2 Emax values for morphine + naltrexone were significantly reduced vs morphine alone (42.9 mm Hg vs 47.1 mm Hg, p < 0.0001) and were not significantly different vs placebo (41.9 mm Hg). Median time to reach maximal effect (TEmax) was delayed for morphine + naltrexone vs morphine alone (5.0 h vs 1.0 h).ConclusionsResults provide preliminary evidence that the naltrexone:morphine ratio within MS-sNT is sufficient to significantly reduce EtCO2 when administered intravenously to non-dependent male recreational opioid-users. Further studies with multiple measures of respiratory-function are warranted to determine if risk of respiratory depression is also reduced by naltrexone in the tampered formulation.

Impact of Intravenous Naltrexone on Intravenous Morphine-Induced High, Drug Liking, and Euphoric Effects in Experienced, Nondependent Male Opioid Users

Background: Opioid analgesics can be abused by crushing followed by solubilization and intravenous injection to attain rapid absorption. Morphine sulfate and naltrexone hydrochloride extended release capsules (EMBEDA®, MS-sNT), indicated for management of chronic, moderate to severe pain, contain pellets of morphine sulfate with a sequestered naltrexone core. Should product tampering by crushing occur, the sequestered naltrexone is intended for release to reduce morphine-induced subjective effects.Objective: This study compared self-reports of high, euphoria, and drug-liking effects of intravenous morphine alone versus intravenous morphine combined with naltrexone in a clinical simulation of intravenous abuse of crushed MS-sNT.Methods: This single-center, randomized, double-blind, crossover study characterized subjective effects of naltrexone administered intravenously at the same ratio to morphine present in MS-sNT. Subjects were male and had used prescription opioids five or more times within the previous 12 months to get ‘high’ but were not physically dependent on opioids. The primary outcome was the response to the Drug Effects Questionnaire (DEQ) question #5, “How high are you now?” (100mm Visual Analog Scale [VAS]). The secondary outcome was the response to a Cole/Addiction Research Center Inventory (ARCI) Stimulation-Euphoria modified scale. Additional outcomes included resonse to VAS drug liking, the remaining DEQ questions, and pupillometry.Results: Administration of intravenous naltrexone following intravenous morphine diminished mean high (29.8 vs 85.2 mm), Cole/ARCI Stimulation-Euphoria (13.7 vs 27.8 mm), and drug-liking (38.9 vs 81.4 mm) scores (all p < 0.0001) compared with intravenous morphine alone. No serious adverse events occurred as a result of the tested ratio of naltrexone to morphine.Conclusions: Results in this study population suggest that naltrexone added to morphine in the 4% ratio within MS-sNT mitigates the high, euphoria, and drug liking of morphine alone, potentially reducing the attractiveness for product tampering. Assessment of the true clinical significance of these findings will require further study.

Impact of Intravenous Naltrexone on Intravenous Morphine-Induced High, Drug Liking, and Euphoric Effects in Experienced, Nondependent Male Opioid Users

Background: Opioid analgesics can be abused by crushing followed by solubilization and intravenous injection to attain rapid absorption. Morphine sulfate and naltrexone hydrochloride extended release capsules (EMBEDA®, MS-sNT), indicated for management of chronic, moderate to severe pain, contain pellets of morphine sulfate with a sequestered naltrexone core. Should product tampering by crushing occur, the sequestered naltrexone is intended for release to reduce morphine-induced subjective effects. Objective: This study compared self-reports of high, euphoria, and drug-liking effects of intravenous morphine alone versus intravenous morphine combined with naltrexone in a clinical simulation of intravenous abuse of crushed MS-sNT. Methods: This single-center, randomized, double-blind, crossover study characterized subjective effects of naltrexone administered intravenously at the same ratio to morphine present in MS-sNT. Subjects were male and had used prescription opioids five or more times within the previous 12 months to get ‘high’ but were not physically dependent on opioids. The primary outcome was the response to the Drug Effects Questionnaire (DEQ) question #5, “How high are you now?” (100mm Visual Analog Scale [VAS]). The secondary outcome was the response to a Cole/Addiction Research Center Inventory (ARCI) Stimulation-Euphoria modified scale. Additional outcomes included resonse to VAS drug liking, the remaining DEQ questions, and pupillometry. Results: Administration of intravenous naltrexone following intravenous morphine diminished mean high (29.8 vs 85.2 mm), Cole/ARCI Stimulation-Euphoria (13.7 vs 27.8 mm), and drug-liking (38.9 vs 81.4 mm) scores (all p < 0.0001) compared with intravenous morphine alone. No serious adverse events occurred as a result of the tested ratio of naltrexone to morphine. Conclusions: Results in this study population suggest that naltrexone added to morphine in the 4% ratio within MS-sNT mitigates the high, euphoria, and drug liking of morphine alone, potentially reducing the attractiveness for product tampering. Assessment of the true clinical significance of these findings will require further study.

Opioid Titration and Conversion in Patients Receiving Morphine Sulfate and Naltrexone Hydrochloride Extended Release Capsules

Objective: To determine the number of steps and identify characteristics associated with attaining a stable dose of morphine sulfate and sequestered naltrexone extended release capsules (MS-sNT). Patients and Methods: Data from an open-label, long-term multicenter study designed to assess the safety of MS-sNT for managing chronic (≥ 3 m), moderate-to-severe pain were analyzed post hoc. Initial MS-sNT dose was 20 mg twice daily (BID) for opioid-naïve patients and 50% to 75% of current daily opioid dose for opioid-experienced patients. Dose adjustments upward/downward were allowed throughout the study with ≥ 3 days between increases; opioid-experienced patients could increase ≥ 24 hours after initial drug dispensing. Nonopioid analgesics were permitted as rescue medication. Stable dose was defined post hoc as one maintained for 2 consecutive study visits. Results: Overall, 69% of patients (n = 319/465) achieved a stable dose; 85% (n = 272) achieved a stable dose in ≤ 2 titration dose adjustments or “steps,” and 96% (n = 305) achieved a stable dose in ≤ 4 steps. The mean time to stable dose was 28.9 days (standard deviation [SD], 34.1 days); the median was 12 days. A stable dose was achieved in 70% (118/168) of opioid-naïve patients (mean, 24.2 days [SD, 33.4 days]; median, 8 days) and 68% (201/297) of opioid-experienced patients (mean, 31.7 days [SD, 34.3 days]; median, 25 days). A stable dose was achieved by 79% (19/24) of patients who previously used morphine, 64% (27/42) who used oxycodone, 59% (47/79) who used hydrocodone, and 71% (83/117) who used multiple opioids. Baseline pain scores were similar between patients who did and did not achieve a stable dose. At the time of stable dose achievement, average, least, worst, and current pain were all decreased from baseline. Conclusions: The study provides information about anticipated rates of achieving stable opioid dose in patients who received MS-sNT for up to 1 year to manage chronic, moderate-to-severe pain. Both opioid-naïve and opioid-experienced patients achieved a stable dose of MS-sNT, generally in ≤ 2 steps. Opioid experience and previous opioid use may influence ability to achieve a stable dose and number of steps required. More studies are needed on the anticipated experience of opioid titration/conversion to help physicians and patients set expectations for initiation of and conversion between opioid therapies.

Morphine Sulfate and Naltrexone Hydrochloride Extended-Release Capsules: Naltrexone Release, Pharmacodynamics, and Tolerability

Background: Morphine sulfate and naltrexone hydrochloride extended-release capsules (EMBEDA, King Pharmaceuticals, Inc., Bristol, TN), indicated for management of chronic, moderate-to-severe pain, contain pellets of extended-release morphine sulfate with a sequestered naltrexone core (MS-sNT). Taken as directed, morphine provides analgesia while naltrexone remains sequestered; if tampered with by crushing, naltrexone is released to mitigate morphine-induced euphoric effects. While it is necessary to establish that formulations intended to reduce attractiveness for abuse are successful in doing so, it is also necessary to demonstrate that product therapeutic integrity is maintained for patients. Objectives: Data were reviewed from 3 studies to determine: 1) the quantity of naltrexone released when MS-sNT pellets are crushed (MS-sNTC) for at least 2 minutes with mortar and pestle); 2) the extent to which the naltrexone released upon crushing mitigated morphine-induced subjective effects; and 3) whether sequestered naltrexone precipitates opioid withdrawal when MSsNT is taken as directed. Methods: The naltrexone bioavailability study compared naltrexone release from MS-sNTC with that from whole intact MS-sNT capsules (MS-sNTW) and an equal naltrexone solution (NS) dose. Equivalent bioavailability was established if 90% confidence intervals (CIs) for geometric mean ratios (maximum plasma naltrexone concentration [Cmax] and area under the concentration-time curve extrapolated to infinity [AUC∞]) fell between 80% and 125%. The oral pharmacodynamic study assessed drug liking and euphoria and pharmacokinetic properties of MS-sNTC and MS-sNTW compared with morphine sulfate solution (MSS) and placebo. The 12-month, open-label (OL) safety study evaluated safety of MS-sNT administered orally as directed in patients with chronic, moderate-to-severe pain. Safety assessments included withdrawal symptoms based on the Clinical Opiate Withdrawal Scale (COWS). Results: Naltrexone from MS-sNTC met criteria for equivalent bioavailability to NS. Although morphine relative bioavailability was similar for MS-sNTC and MSS, mean peak (Emax) visual analog scale (VAS) scores for drug liking and Cole/Addiction Research Center Inventory Stimulation-Euphoria were significantly reduced for MS-sNTC vs MSS (P &lt; 0.001). In these 2 studies, a total of 6 participants had one measurement of plasma naltrexone after MS-sNTW that was above the lower limit of quantification. In the OL safety study, 72/93 participants (77%) had no quantifiable naltrexone concentrations. There was neither evidence of naltrexone accumulation for any participant nor any significant correlation with MSsNT dose, age, or sex. Of 4 participants with the highest naltrexone concentrations, none had COWS scores consistent with moderate opioid withdrawal symptoms. Only 5 participants had COWS scores consistent with moderate opioid withdrawal; all 5 had not taken MS-sNT as directed. Limitations: Study populations may not be fully representative of patients receiving opioid therapy for the management of chronic, moderate-to-severe pain and of opioid abusers. Conclusions: When MS-sNT capsules are crushed, all of the sequestered naltrexone (relative to oral NS) is released and immediately available to mitigate morphine-induced effects. When MSsNT was crushed, the naltrexone released abated drug liking and euphoria relative to that from an equal dose of immediate-release morphine from MSS administration in a majority of participants. Naltrexone concentrations were low over a period of 12 months without evidence of accumulation, and there were no observable opioid withdrawal symptoms when MS-sNT was taken as directed. Key words: Chronic pain, drug liking, euphoria, extended-release opioids, morphine, naltrexone, opioid withdrawal, pharmacodynamics, pharmacokinetics

Morphine sulfate and naltrexone hydrochloride extended release capsules for the management of chronic, moderate-to-severe pain, while reducing morphine-induced subjective effects upon tampering by crushing

Introduction: Public concern over the increased incidence of prescription opioid abuse has prompted the development of products designed to be less attractive for abuse. This article characterizes morphine sulfate and naltrexone hydrochloride extended release capsules (MS-sNT), the first long-acting opioid approved in the USA for the management of chronic, moderate-to-severe pain that is also designed to reduce drug liking and euphoria if tampered with by crushing.Areas covered: This article reviews the pharmacokinetics, pharmacodynamics, efficacy and safety of MS-sNT when taken as directed by patients with chronic, moderate-to-severe pain and when tampered with by crushing. A literature search was conducted using Medline, Embase and Biosis for the years from 1995 to January 2011, limited to humans and the English language. Search terms varied with the structure of the databases, and included ‘naltrexone’ and ‘morphine’, ‘delayed-action preparations’, ‘drug combinations’, ‘extended-’, ‘slow-’ or ‘controlled-release’, ‘combinations’ and ‘EMBEDA’. Also included were congress presentations available from the manufacturer.Expert opinion: Although no product is likely to be abuse-proof in the hands of clever and determined abusers, new opioid products, such as MS-sNT, may potentially help physicians provide analgesia while at the same time providing a potential way to address the risk of misuse, abuse and diversion. Epidemiological studies are required to determine the impact of such products on real-world abuse.

Morphine sulfate and naltrexone hydrochloride extended release capsules (MS-sNT; EMBEDA®), when crushed and injected, mitigate morphine-induced respiratory depression

Opioid-induced respiratory depression remains a major public health concern. With half of all drug-related deaths due to prescription drug abuse/misuse, respiratory depression is the leading cause of death following a lethal opioid dose. Morphine can induce respiratory depression which may become fatal within 3 hours of an overdose; however, it may be reversed by the timely administration of an opioid antagonist. Unfortunately, timely intervention is not always available. Morphine is often abused intravenously where respiratory depression can occur in minutes.

The Relative Bioavailability of Morphine Sulfate and Naltrexone Hydrochloride Extended Release Capsules (EMBEDA®) and an Extended Release Morphine Sulfate Capsule Formulation (KADIAN®) in Healthy Adults Under Fasting Conditions

Morphine sulfate and naltrexone hydrochloride extended release capsules (EMBEDA®, King Pharmaceuticals®, Inc., Bristol, TN), indicated for the management of chronic, moderate to severe pain, contain extended release morphine pellets with a sequestered naltrexone core (MS-sNT). If the product is tampered with by crushing, naltrexone, a μ-opioid antagonist, is intended for release to mitigate morphine-induced subjective effects. The primary end point of this randomized 2-way crossover study in healthy fasted volunteers was evaluation of morphine bioequivalence between MS-sNT (treatment A) and morphine sulfate extended release capsules (KADIAN®, treatment B). Morphine pharmacokinetics were assessed predose to 72 hours postdose of single 100-mg doses of treatment A or B. Analysis of variance of ln-transformed ratios of least squares mean of the area under the concentration time curve (AUC) from time 0 to last measurable concentration (AUC0-t) and AUC from time 0 to infinity (AUCinf) and maximum serum concentration (Cmax) for treatments A versus B were performed. Ratios and 90% confidence intervals for least squares mean for AUC0-t (102.2%; 98.6-105.9%), AUCinf (97.4%; 91.2-104.1%), and Cmax (93.8%; 82.4-106.7%) indicated bioequivalence between the 2 formulations. When subjects who vomited during the 12-hour dosing interval were excluded, the confidence interval for AUC0-t and AUCinf fell within the 80%-125% range, but the lower limit for Cmax was 76.9%.

Long-Term Safety and Efficacy of Morphine Sulfate and Naltrexone Hydrochloride Extended Release Capsules, a Novel Formulation Containing Morphine and Sequestered Naltrexone, in Patients with Chronic, Moderate to Severe Pain

Morphine sulfate and naltrexone hydrochloride extended release capsules contain extended-release pellets of morphine with a sequestered naltrexone core (MS-sNT). Taken whole, as intended, morphine is released to provide pain relief; if tampered with by crushing, naltrexone is released to mitigate subjective effects of morphine. This open-label study assessed long-term (12-month) safety of MS-sNT in patients with chronic, moderate to severe pain. Safety assessments included determining adverse events (AEs), laboratory assessments, and the Clinical Opiate Withdrawal Scale (COWS). Analgesic efficacy was assessed (diary) as worst, least, average, and current pain using an 11-point numeric scale (0=none; 10=worst). Of 465 patients receiving one or more doses, 160 completed the study. Most patients (81.3%) experienced one or more AEs, most commonly constipation (31.8%) or nausea (25.2%). Thirty-three patients (7.1%) reported serious AEs; one patient's severe gastrointestinal inflammation and colitis were considered possibly study drug-related. Most discontinuations (30%) occurred in the first month, most often because of AEs (23.7%). There were no clinically relevant changes in laboratory results or vital signs, and no clinically significant electrocardiogram changes deemed study drug-related. During each visit after Week 1, 5% or fewer patients had COWS scores indicating mild withdrawal symptoms (range, 0%-4.8%). Five patients, who did not take the study drug as instructed, had scores consistent with moderate withdrawal. MS-sNT yielded statistically significant improvements from baseline in mean scores for all pain diary items for all visits, except Week 1 for least pain. In this study population, when MS-sNT was taken as directed for chronic, moderate to severe pain for up to 12 months, most AEs were typical opioid-related side effects. Mean COWS scores remained low, indicating lack ofwithdrawal symptoms and appropriate transition off the study drug at completion.

Food effects on the pharmacokinetics of morphine sulfate and naltrexone hydrochloride extended release capsules

Morphine sulfate and naltrexone hydrochloride extended release capsules, indicated for chronic moderate-to-severe pain, contain extended-release morphine pellets with a sequestered naltrexone core. If pellets are tampered by crushing, naltrexone is released to reduce morphine-induced effects that appeal to opioid abusers. The primary objective of this study was to assess single-dose relative bioavailability of morphine when morphine sulfate and naltrexone hydrochloride extended release capsules were taken under fed and fasting conditions and when pellets were sprinkled on apple sauce. This was a single-center, randomized, open-label study in 36 healthy adult volunteers. Subjects took a 100-mg morphine sulfate and naltrexone hydrochloride extended release capsule intact with 240 mL water, under fed and fasted conditions, and when the capsule was opened and pellets were sprinkled over apple sauce and consumed without chewing; each treatment was separated by a 14-day washout. Plasma samples were collected just before dosing through 72 hours postdose for pharmacokinetic analyses of morphine, and through 168 hours postdose for naltrexone and its major metabolite 6-β-naltrexol. Morphine bioavailability was similar for all treatments. There was a lack of sprinkle effect (sprinkle vs. whole, fasted); 90% confidence intervals (CIs) of ratios of log-transformed least squares means for area under the plasma concentration-time curve (AUC) and peak plasma concentration (C(max)) fell within 80%-125% boundaries. For the food effect, 90% CIs were within the boundaries for AUC, but C(max) was reduced and time to C(max) was delayed by 2.5 hours under fed conditions. Naltrexone remained sequestered under all treatment conditions with only trace systemic exposure. Results indicated that morphine sulfate and naltrexone hydrochloride extended release capsules can be administered without regard to meals, and contents can be sprinkled over apple sauce and consumed without chewing by patients with difficulty swallowing.

Morphine Sulfate and Naltrexone Hydrochloride Extended Release Capsules in Patients with Chronic Osteoarthritis Pain

Objective: To assess the efficacy and safety of morphine sulfate and naltrexone hydrochloride extended release capsules (EMBEDA®; MS-sNT), which contain morphine sulfate pellets with a sequestered naltrexone core, in treating patients with chronic, moderate-to-severe osteoarthritis (hip or knee) pain. Patients and Methods: This phase 3 study had an enriched-enrollment, randomized-withdrawal, double-blind, multicenter design. Patients (N = 547) were titrated to an effective dose of MS-sNT (20–160 mg/day). Responders (n = 344) were randomized to 12 weeks maintenance with an effective MS-sNT dose or were tapered to placebo over 2 weeks. The primary efficacy measure was the change from baseline (CFB) in diary average-pain scores (0–10 scale, Brief Pain Inventory [BPI]) from randomization to the last 7 days of the maintenance period. Secondary efficacy measures included the remaining BPI scores and Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index. Opioid withdrawal symptoms were assessed by the Clinical Opiate Withdrawal Scale (COWS) and Subjective Opiate Withdrawal Scale (SOWS). The study ran from January 10, 2007 through November 8, 2007. Results: MS-sNT maintained pain control better than placebo (mean CFB, diary average-pain score, −0.2 ± 1.9 vs +0.3 ± 2.1; P = 0.045). Change from baseline for MS-sNT pain-diary score (worst, least, average, current) was superior during the maintenance period visits, weeks 2 to 12 (P < 0.05). WOMAC composite score CFB was superior at most visits. MS-sNT was generally well tolerated, with a typical morphine safety profile. No patient taking MS-sNT as directed experienced withdrawal symptoms. Conclusion: MS-sNT provided effective analgesia in patients with chronic, moderate-to-severe osteoarthritis pain, with a safety profile typical of morphine-containing products. Naltrexone sequestered in MS-sNT had no clinically relevant effect when MS-sNT was taken as directed.

Relative oral bioavailability of morphine and naltrexone derived from crushed morphine sulfate and naltrexone hydrochloride extended-release capsules versus intact product and versus naltrexone solution: A single-dose, randomized-sequence, open-label, three-way crossover trial in healthy volunteers

Background: Morphine sulfate/sequestered naltrexone hydrochloride (HCl) (MS-sNT) extended-release fixed-dose combination capsules, approved by the US Food and Drug Administration (FDA) in August 2009 for chronic moderate to severe pain, contain extended-release morphine pellets with a sequestered core of the opioid antagonist naltrexone. MS-sNT was designed so that if the product is tampered with by crushing, the naltrexone becomes bioavailable to mitigate morphine-induced subjective effects, rendering the product less attractive for tampering. Objectives: The primary aim of this study was to compare the oral bioavailability of naltrexone and its metabolite 6-β-naltrexol, derived from crushed pellets from MS-sNT capsules, to naltrexone solution. This study also assessed the relative bioavailability of morphine from crushed pellets from MS-sNT capsules and that from the whole, intact product. Methods: This single-dose, randomized-sequence, open-label, 3-period, 3-treatment crossover trial was conducted in healthy volunteers. Adults admitted to the study center underwent a 10-hour overnight fast before study drug administration. Each subject received all 3 of the following treatments, 1 per session, separated by a 14-day washout: tampered pellets (crushed for ≥2 minutes with a mortar and pestle) from a 60-mg MS-sNT capsule (60 mg morphine/2.4 mg naltrexone); 60-mg whole, intact MS-sNT capsule; and oral naltrexone HCl (2.4 mg) solution. Plasma concentrations of naltrexone and 6-β-naltrexol were measured 0 to 168 hours after administration. Morphine pharmaco-kinetics of crushed and whole pellets were determined 0 to 72 hours after administration. The analysis of relative bioavailability was based on conventional FDA criteria for assuming bioequivalence; that is, 90% CIs for ratios of geometric means (natural logarithm [In]-transformed C max and AUC) fell within the range of 80% to 125%. Subjects underwent physical examinations, clinical laboratory tests, and ECG at screening and study discharge and were monitored for adverse events (AEs) throughout the study. Results: Of the 24 subjects enrolled in the study, 23 completed it. Most subjects were white (79%) and male (63%); the mean (SD) age was 39.3 (11.2) years and the mean weight was 77.6 (13.5) kg (range, 55.0102.5 kg). Plasma C max and AUC 0-t of naltrexone after the administration of crushed pellets of MS-sNT (579 pg/mL and 1811 h · pg/mL, respectively) and naltrexone solution (584 pg/mL and 1954 h · pg/mL) were not significantly different; 90% CIs were 83.8% to 116% and 83.3% to 102%, meeting the regulatory requirements for assuming bioequivalence in this study population. Plasma naltrexone concentration was below the lower limit of quantitation (4.0 pg/mL) in 23 of 24 subjects (96%) after whole MS-sNT administration. Morphine AUC 0-t was not significantly different whether MS-sNT was crushed (163 h · ng/mL) or administered whole (174 h · ng/mL), but C max was numerically higher (24.5 vs 7.7 ng/mL) and T max was numerically shorter (2.00 vs 7.03 hours) with MS-sNT crushed versus whole. The most commonly reported AEs were nausea (8/23 [35%], 10/24 [42%], and 3/23 [13%] subjects in the crushed, whole, and naltrexone groups, respectively) and emesis (6 [26%], 7 [29%], and 2 [9%]). Conclusions: In this single-dose study, when pellets from MS-sNT were crushed, naltrexone appeared to be completely released and available to mitigate morphine-induced effects. When MS-sNT was administered whole, morphine was released in an extended-release fashion while naltrexone remained sequestered.