Benefits of Extended-Release Opioid Analgesic Formulations in the Treatment of Chronic Pain

Trends of opioid use following anterior cervical discectomy and fusion: A 10-year longitudinal study of the Veterans Health Administration

Background

The United States Veteran Health Administration (VHA) cares for a substantial group of patients who are at higher risk of substance abuse in comparison to the general population. The purpose of this study was to (1) examine opioid consumption in the veteran population both pre- and postoperatively to anterior cervical discectomy and fusion (ACDF) and (2) understand the risk factors that are associated with sustained postoperative opioid use.

Methods

A retrospective database study was conducted using the Veterans Affairs Informatics and Computing Infrastructure database. Patients who underwent ACDF between 2010 and 2020 were identified and stratified into 3 groups based on their preoperative opioid usage prior to the procedure: opioid naïve, low preoperative opioid use (1-3 preoperative claims), and high preoperative opioid use (≥4 preoperative claims). Cumulative pre- and postoperative opioid usage for each patient was calculated in Morphine Milligram Equivalents (MME).

Results

A total of 7,894 patients were identified with 3,929 (49.7%) opioid naïve, 1,813 (23.0%) low preoperative opioid use, and 2,152 (27.3%) high opioid usage. The proportion of patients in the opioid-naïve cohort, low preoperative usage cohort, and high preoperative opioid usage cohort, that remained on opioids 1 year postoperatively was 13.1%, 31.3%, and 77.8%, respectively. At 1 year postoperatively, the median opioid MME significantly decreased pre- to postoperatively (25.0 vs. 0, p<.006). High preoperative opioid consumption was found to be the greatest risk factor for continued chronic opioid use (OR 17.1, p<.001).

Conclusions

Following ACDF procedures, opioid consumption significantly decreased; however, at 1 year, over one-third of patients remained on opioid therapy. A disproportionate number of patients who remained on chronic opioid therapy had high preoperative opioid consumption. Notably, increased scrutiny and policy changes regarding opioids, which began around 2017, resulted in a significant reduction in preoperative opioid use by 2020 compared to a decade earlier.

Abuse and misuse of tramadol in patients with non-oncologic pain in a region of Southern Europe

Background

Tramadol can cause dependence even within the recommended dose range. Its use has increased recently, especially in patients with chronic pain, and although a growing body of literature identifies a non-therapeutic use, patterns of misuse of tramadol is so far limited.

Methods

Two-year observational and cross-sectional study (January 2020 - December 2021) was conducted in 75 community pharmacies from Catalonia. To estimate the potential abuse and misuse of tramadol by patients visiting community pharmacy, and to establish the demographic characteristics of the tramadol users, a validated questionnaire based on the Finch criteria was designed. A total of 251 cases were registered.

Results

Data show that women were more involved (56.6%) and the highest proportion was found in the age interval of 46-65 years (42.6%). The combination of tramadol and paracetamol was reported in 54.6% of the cases and 73.7% corresponded to immediate-release tablets. In 93.6% of the cases, the request was preceded by previous use. Conversely, young men showed a higher non-prescription request for tramadol, reporting acute pain (p < 0.05). These results indicate that there is non-therapeutic use among patients who visit community pharmacies for information on two profiles.

Conclusion

This study shows that being an aged woman and suffering from chronic pain seems to involve a risk of generating dependence on tramadol. Likewise, a suspicion of recreational use of tramadol by young people has also been identified. There is a need to investigate how to manage chronic pain, given its complexity and take into account the risk of misuse that may come with tramadol. The involvement of characteristics such as gender as well as the pharmaceutical form in the development of tramadol misuse also needs to be analysed deeply. It is mandatory to evaluate the criteria for prescribing tramadol and initiatives to improve the knowledge of the health professionals and the population.

Three-Dimensional Covalent Organic Framework with Topology for Drug Delivery

Three-dimensional (3D) covalent organic frameworks (COFs) exemplify a new generation of crystalline extended solids with intriguing structures and unprecedented porosity. Notwithstanding substantial scope, the reticular synthesis of 3D COFs from pre-designed building units leading to new network topologies yet remains a demanding task owing to the shortage of 3D building units and inadequate reversibility of the linkages between the building units. In this work, by linking a tetragonal prism (8-connected) node with a square planar (4-connected) node, we report the first 3D COF with scu-c topology. The new COF, namely, TUS-84, features a two-fold interpenetrated structure with well-defined porosity and a Brunauer-Emmett-Teller surface area of 679 m² g^-1. In drug delivery applications, TUS-84 shows efficient drug loading and sustained release profile.

Design, Synthesis, and Structure-Activity Relationship Exploration of Alkyl/Phenylalkyl Piperidine Analogues as Novel Highly Potent and Selective μ Opioid Receptor Agonists

Pain was implicated in many diseases. Despite effectiveness to treat moderate to severe pain, opioid analgesics elicited many side effects, greatly limiting their prescription in clinics. Based on M1, an active metabolite of tramadol, 3-((dimethylamino)methyl)-4-(3-hydroxyphenyl)piperidin-4-ol analogues were designed, synthesized, and evaluated in vitro. Among all the compounds tested, compound 23 was found to be a novel, highly selective, and potent MOR agonist (K_i MOR = 0.0034 nM, EC_50 MOR = 0.68 nM, E_max = 206.5%; K_i DOR = 41.67 nM; K_i KOR = 7.9 nM). Structure-activity relationship exploration showed that the linker between the piperidine ring and the phenyl ring as well as substituent pattern of the phenyl ring played a pivotal role in binding affinity and selectivity. (3R, 4S)-23 (K_i MOR = 0.0021 ± 0.0001 nM, EC_50 MOR = 0.0013 ± 0.0001 nM, E_max = 209.1 ± 1.4%; K_i DOR = 18.4 ± 0.7 nM, EC_50 DOR = 74.5 ± 2.8 nM, E_max = 267.1 ± 1.4%; K_i KOR = 25.8 ± 0.2 nM, EC_50 DOR = 116.2 ± 4.4 nM, E_max = 209.5 ± 1.4%) had more potent activity for opioid receptors than its enantiomer (3S, 4R)-23 and was found to be a potent, highly selective MOR agonist with novel scaffold. High binding affinity and selectivity of (3R, 4S)-23 for MOR over KOR and DOR and its mechanism of activating MOR were proposed by docking and molecular dynamics simulations, respectively.

Discovery of 3-((dimethylamino)methyl)-4-hydroxy-4-(3-methoxyphenyl)-N-phenylpiperidine-1-carboxamide as novel potent analgesic

Management of moderate to severe pain by clinically used opioid analgesics is associated with a plethora of side effects. Despite many efforts have been dedicated to reduce undesirable side effects, moderate progress has been made. In this work, starting from Tramadol, a series of 3-((dimethylamino)methyl)-4-hydroxy-4-(3-methoxyphenyl)piperidine-1-carboxamide derivatives were designed and synthesized, and their in vitro and in vivo activities were evaluated. Our campaign afforded selective μ opioid receptor (MOR) ligand 2a (K_iMOR: 7.3 ± 0.5 nM; K_iDOR: 849.4 ± 96.6 nM; K_iKOR: 49.1 ± 6.9 nM) as potent analgesic with ED₅₀ of 3.1 mg/kg in 55 °C hot plate model. Its antinociception effect was blocked by opioid antagonist naloxone. High binding affinity toward MOR of compound 2a was associated with water bridge, salt bridge, hydrogen bond and hydrophobic interaction with MOR. The high selectivity of compound 2a for MOR over δ opioid receptor (DOR) and κ opioid receptor (KOR) was due to steric hindrance of compound 2a with DOR and KOR. 2a, a compound with novel scaffold, could serve as a lead for the development of novel opioid ligands.

Healthcare Costs And Resource Utilization In Chronic Pain Patients Treated With Extended-Release Formulations Of Tapentadol, Oxycodone, Or Morphine Stratified By Type Of Pain: A Retrospective Claims Analysis, 2012-2016

Purpose

Chronic pain treatment imposes a substantial economic burden on US society. Treatment costs may vary across subgroups of patients with different types of pain. The aim of our study was to compare healthcare costs (HC) and resource utilization in musculoskeletal (MP), neuropathic (NP), and cancer pain (CaP) patients treated with long-acting opioids (LAO), using real-world evidence.

Patients and methods

We compared total HC and resource utilization in subgroups of chronic pain patients (MP, NP or CaP) treated with three LAO alternatives: morphine-sulfate extended-release (MsER), oxycodone ER (OxnER) and tapentadol ER (TapER). Retrospective claims data were analyzed in the IBM Truven Health MarketScan^® Commercial Claims Database (October 2012 through March 2016). All patients were continuously health plan enrolled for at least 12 months before the index date (first LAO prescription date) and during the LAO-treatment period. The cohorts were propensity-score matched.

Results

A total of 2824 TapER-treated patients were matched to 16,716 OxnER-treated patients, while 2827 TapER patients were matched to 16,817 MsER patients. The average monthly total HC were lower in the TapER than in the OxnER cohort ($2510 vs. $3720, p<0.001), reflecting significantly lower outpatient, inpatient and emergency department visit rates in the TapER cohort. Similarly, the TapER cohort exhibited a lower average monthly total HC ($2520 vs. $2900, p<0.05) than MsER cohort, with significantly fewer inpatient and outpatient visits in the TapER cohort. TapER demonstrated significantly lower total HC than OxnER in patients with NP and MP, and similar to OxnER in CaP patients. TapER costs were similar to MsER costs in all pain-type subpopulations.

Conclusion

Based on real-world evidence, the TapER treatment for chronic pain was associated with significantly lower HC compared with MsER or OxnER. When categorized by type of pain, TapER remained a less costly strategy in comparison with OxnER for MP and NP.

Application of simplex lattice design for the development of extended release tablets of model drug diclofenac sodium

Aim: Simplex lattice design was applied to predict extent of drug release from extended release diclofenac sodium tablets. Methods: The effects of composition on dissolution rate were evaluated by varying the levels of hydroxypropyl methylcellulose, dicalcium phosphate and cornstarch via three component design. Results: The rate of drug release was primarily dictated by the proportion of hydroxypropyl methylcellulose and was also affected by the proportion of dicalcium phosphate and the method of processing (direct compression/wet granulation). Polynomial equations constructed for directly compressed and wet-granulated formulations could successfully predict the extent of drug release at an arbitrary time point of 3 h. Conclusion: Simplex lattice design is a viable tool to predict the drug release patterns of extended release formulations.

Assessment of the Abuse Potential of Cebranopadol in Nondependent Recreational Opioid Users: A Phase 1 Randomized Controlled Study

BACKGROUND

Cebranopadol is a nociceptin/orphanin FQ peptide/opioid receptor agonist with central antinociceptive activity. We hypothesize that this novel mechanism of action may lead to a lower risk of abuse compared with pure μ-opioid peptide receptor agonists.

METHODS

We conducted a single-dose, nested-randomized, double-blind crossover study in nondependent recreational opioid users to evaluate the abuse potential of single doses of cebranopadol relative to hydromorphone immediate release and placebo. The study consisted of a qualification phase and a 7-period treatment phase (cebranopadol 200, 400, and 800 μg; hydromorphone 8 and 16 mg; and 2 placebos). The primary end point was the peak effect of drug liking at this moment, measured by visual analog scale (VAS). Various secondary end points (eg, VAS rating for good drug effects, high, bad drug effects, take drug again, drug similarity, and pupillometry) were also investigated.

RESULTS

Forty-two subjects completed the study. Cebranopadol 200 and 400 μg did not differentiate from placebo on the abuse potential assessments and generated smaller responses than hydromorphone. Responses observed with cebranopadol 800 μg were similar to hydromorphone 8 mg and smaller than hydromorphone 16 mg. The maximum effect for VAS drug liking at this moment was delayed compared with hydromorphone (3 and 1.5 hours, respectively). Cebranopadol administration was safe; no serious adverse events or study discontinuation due to treatment-emergent adverse events occurred.

CONCLUSIONS

These results confirm our hypothesis that cebranopadol, a nociceptin/orphanin FQ peptide/opioid receptor agonist, has lower abuse potential than hydromorphone immediate release, a pure μ-opioid peptide agonist.

Are Prescription Opioids Driving the Opioid Crisis? Assumptions vs Facts

Objective

Sharp increases in opioid prescriptions, and associated increases in overdose deaths in the 2000s, evoked widespread calls to change perceptions of opioid analgesics. Medical literature discussions of opioid analgesics began emphasizing patient and public health hazards. Repetitive exposure to this information may influence physician assumptions. While highly consequential to patients with pain whose function and quality of life may benefit from opioid analgesics, current assumptions about prescription opioid analgesics, including their role in the ongoing opioid overdose epidemic, have not been scrutinized.

Methods

Information was obtained by searching PubMed, governmental agency websites, and conference proceedings.

Results

Opioid analgesic prescribing and associated overdose deaths both peaked around 2011 and are in long-term decline; the sharp overdose increase recorded in 2014 was driven by illicit fentanyl and heroin. Nonmethadone prescription opioid analgesic deaths, in the absence of co-ingested benzodiazepines, alcohol, or other central nervous system/respiratory depressants, are infrequent. Within five years of initial prescription opioid misuse, 3.6% initiate heroin use. The United States consumes 80% of the world opioid supply, but opioid access is nonexistent for 80% and severely restricted for 4.1% of the global population.

Conclusions

Many current assumptions about opioid analgesics are ill-founded. Illicit fentanyl and heroin, not opioid prescribing, now fuel the current opioid overdose epidemic. National discussion has often neglected the potentially devastating effects of uncontrolled chronic pain. Opioid analgesic prescribing and related overdoses are in decline, at great cost to patients with pain who have benefited or may benefit from, but cannot access, opioid analgesic therapy.

The comparative pharmacokinetics of physical manipulation by crushing of Xtampza® ER compared with OxyContin®

AIM

To further characterize the pharmacokinetics of Xtampza^® ER.

SUBJECTS & METHODS

This was an open-label, randomized, active-controlled, five-treatment, five-period, naltrexone-blocked, cross-over study. Healthy subjects received five equivalent oxycodone doses: Xtampza ER (intact or crushed), OxyContin^® (intact or crushed) or immediate-release (IR) oxycodone (crushed). Blood samples were collected to assess oxycodone concentrations.

RESULTS

Crushed and intact Xtampza ER resulted in lower peak plasma concentrations compared with crushed oxycodone IR; crushed and intact Xtampza ER were bioequivalent. Crushed OxyContin exhibited a rapid increase in plasma oxycodone and was bioequivalent to crushed oxycodone IR.

CONCLUSION

This second pharmacokinetic study demonstrated that Xtampza ER maintains its ER properties after crushing, unlike OxyContin, which failed to retain its ER properties after crushing. ANZCTR registration number: ACTRN12614000613606.

Pharmacokinetics and Pharmacodynamics Evaluation of Tramadol in Thermoreversible Gels

We evaluated pharmacokinetics (PK) and pharmacodynamics (PD) induced by new formulations of tramadol (TR) in thermoreversible gels. The poloxamer- (PL-) tramadol systems were prepared by direct dispersion of the drug in solutions with PL 407 and PL 188. The evaluated formulations were as follows: F1: TR 2% in aqueous solution and F2: PL 407 (20%) + PL 188 (10%) + TR 2%; F3: PL 407 (25%) + PL 188 (5%) + TR 2%; F4: PL 407 (20%) + TR 2%. New Zealand White rabbits were divided into four groups (n = 6) and treated by subcutaneous route with F1, F2, F3, or F4 (10 μg·kg^-1). PK evaluation used TR and M1 plasma levels. PD evaluation was performed with the measurement of both pupils' diameters. F2 showed higher TR plasma concentration after 180 minutes and presented lower M1 concentrations at almost all evaluated periods. Areas under the curve (ASC_0-480 and ASC_0-∞ ) and clearance of F2 presented differences compared to F1. F2 presented significant correlation (Pearson correlation) between the enhancement of TR and M1 concentrations and the decrease of pupil size (miosis). Thus, F2 was effective in altering pharmacokinetics and pharmacodynamics effects of TR.

Extended-release of opioids using fentanyl-based polymeric nanoparticles for enhanced pain management

Fentanyl-terminated polyesters provide linear release of therapeutics with an effective antinociceptive effect in vivo.

Oxycodone DETERx®: A Novel Abuse-Deterrent, Extended-Release Analgesic Option for the Treatment of Patients with Chronic Pain

BACKGROUND

Extended-release (ER) opioid analgesics are commonly used to provide safe and effective pain relief to treat pain severe enough to require around-the-clock, long-term dosing. These ER opioid formulations usually contain more drug per dosage unit than immediate-release (IR) agents, and therefore bring with them challenges related to both opioid abuse and misuse, often through manipulation of the dosage form. Oxycodone DETERx® (Xtampza® ER, Collegium Pharmaceutical, Inc.) is a novel abuse-deterrent, ER formulation developed to deter common methods of manipulation. In addition to having abuse-deterrent properties, oxycodone DETERx was developed to provide alternative modes of administration for patients with chronic pain and difficulty swallowing.

SCOPE

Using published articles, abstracts, and prescribing information, data supporting the use of oxycodone DETERx are reviewed.

FINDINGS

Oxycodone DETERx was effective at reducing chronic pain in patients enrolled in a pivotal clinical trial, and had a tolerability profile expected of opioids. In addition to administration of the intact capsule, oxycodone DETERx can also be administered by sprinkling directly into the mouth from a dosing cup, onto soft foods, or through nasogastric or gastrostomy tubes, thus providing flexible dosing options for patients who have difficulty swallowing. In vitro studies demonstrated the reduced ability of oxycodone DETERx to be manipulated by common techniques used by abusers to defeat the ER characteristics or prepare the formulation for injection. Pharmacokinetic studies demonstrated that the ER characteristics of oxycodone DETERx are maintained if chewed or crushed. As a result, oxycodone DETERx is currently the only ER-formulated opioid without a boxed warning against crushing or chewing. Human abuse-potential studies conducted in a population of recreational opioid users demonstrated lower drug-liking scores for oxycodone DETERx administered intranasally and orally when compared with IR oxycodone.

FUNDING

Collegium Pharmaceutical, Inc.

An abuse-deterrent, microsphere-in-capsule formulation of extended-release oxycodone: alternative modes of administration to facilitate pain management in patients with dysphagia

BACKGROUND

Patients with chronic pain may experience difficulty swallowing, in part due to worsening disease, comorbid conditions, iatrogenic etiology, or age. Patients or caregivers may manipulate extended-release (ER) opioid formulations to facilitate oral dosing due to a lack of therapeutic options that allow for sprinkle or enteral feeding tube administration. If crushed or broken, current oral ER opioids can be associated with adverse sequelae, including risk of potentially fatal overdose.

OBJECTIVE

To review the safety, in vitro dissolution data, and in vivo pharmacokinetic data that support alternative modes of administration of oxycodone DETERx (Xtampza ER) via sprinkling onto soft foods for oral ingestion or via enteral feeding tubes.

METHODS

A review of oxycodone DETERx data from in vitro and in vivo studies was conducted to demonstrate support for alternative routes and modes of administration.

RESULTS

There was no difference in the dissolution profile when administered with various soft foods or when mixed with various liquid vehicles and administered via nasogastric (NG) or gastrostomy (G) tubes, based on in vitro studies. When sprinkled onto applesauce and administered orally, the microspheres were bioequivalent to the intact oxycodone capsules. When crushed or chewed, the formulation maintained its pharmacokinetic profile; no bolus dose of opioid was released. The sprinkle-dose study was limited by the single-dose study design, as well as the small sample size.

CONCLUSIONS

Oxycodone DETERx is the first ER oxycodone formulation that can be administered either intact, sprinkled onto soft foods, or via NG/G tubes, thereby providing options for treating pain in patients who have difficulty swallowing.

Oral Human Abuse Potential of Oxycodone DETERx® (Xtampza® ER)

Oxycodone DETERx^® (Collegium Pharmaceutical Inc, Canton, Massachusetts) is an extended‐release, microsphere‐in‐capsule, abuse‐deterrent formulation designed to retain its extended‐release properties after tampering (eg, chewing/crushing). This randomized, double‐blind, placebo‐controlled, triple‐dummy study evaluated the oral abuse potential of intact and chewed oxycodone DETERx capsules compared with crushed immediate‐release oxycodone. Subjects with a history of recreational opioid use who were nondependent/nontolerant to opioids were enrolled. Treatments included intact oxycodone DETERx (high‐fat, high‐calorie meal and fasted), chewed oxycodone DETERx (high‐fat, high‐calorie meal and fasted), crushed immediate‐release oxycodone (fasted), and placebo (high‐fat, high‐calorie meal). Plasma samples were collected to determine pharmacokinetic parameters. The primary endpoint was drug liking at the moment; other endpoints included drug effects questionnaire scores, Addiction Research Center Inventory/Morphine Benzedrine Group score, pupillometry measurements, and safety. Thirty‐eight subjects completed the study. Chewed and intact oxycodone DETERx were bioequivalent, unlike crushed immediate‐release oxycodone, which yielded higher peak oxycodone plasma concentrations compared with all methods of oxycodone DETERx administration. The mean maximum (peak) effect (E_max) for drug liking was significantly lower for chewed and intact oxycodone DETERx than for crushed immediate‐release oxycodone (P < .01). The time to E_max was significantly longer for chewed and intact oxycodone DETERx than for crushed immediate‐release oxycodone (P < .0001). Scores for feeling high and Addiction Research Center Inventory/Morphine Benzedrine Group scores demonstrated lower abuse potential for chewed and intact oxycodone DETERx compared with crushed immediate‐release oxycodone. Study treatments were well tolerated; no subjects experienced serious adverse events. These results demonstrate the lower oral abuse potential of chewed and intact oxycodone DETERx than crushed immediate‐release oxycodone.

Analgesic Efficacy of a New Immediate-Release/Extended-Release Formulation of Ibuprofen: Results From Single- and Multiple-Dose Postsurgical Dental Pain Studies

Analgesic effects of ibuprofen immediate‐release/extended‐release (IR/ER) 600‐mg tablets were evaluated in 2 randomized, double‐blind, placebo‐controlled dental pain studies. Patients 16–40 years old with moderate–severe pain following third‐molar extraction received single‐dose ibuprofen 600 mg IR/ER (formulation A or B), naproxen sodium 220 mg, or placebo (2:2:2:1; study 1) or 4 doses of ibuprofen 600 mg IR/ER (formulation A) or placebo (1:1; study 2). In study 1 (n = 196), mean (standard deviation [SD]) time‐weighted sum of pain intensity difference scores for placebo, ibuprofen IR/ER A, ibuprofen IR/ER B, and naproxen, respectively, were 0.05 (9.2), 16.87 (9.4), 17.34 (10.5), and 12.66 (10.0) over 0–12 hours and ‐0.03 (4.1), 6.57 (4.4), 7.14 (5.2), and 5.14 (5.0) over 8–12 hours (all P < .001 vs placebo). In study 2 (n = 106), mean (SD) time‐weighted sum of pain relief and pain intensity difference scores were 18.2 (20.0) versus 41.5 (21.0) at 0–12 hours and 10.3 (12.0) versus 18.4 (12.1) at 8–12 hours for placebo versus ibuprofen IR/ER, respectively (P < .001 for both); efficacy was sustained over each of the four 12‐hour dosing intervals with ibuprofen. Gastrointestinal adverse events predominated with placebo both after study medication administration and after rescue medication use, if applicable. Ibuprofen 600 mg IR/ER provided safe and effective analgesia after single and multiple doses.

Consumer self-selection, safety, and compliance with a novel over-the-counter ibuprofen 600-mg immediate-release and extended-release tablet

OBJECTIVE

The extent to which people comply with labeled instructions for use of long-acting over-the-counter analgesics is largely unknown; this study evaluated whether consumers can correctly select and use a new long-acting ibuprofen 600-mg immediate-release and extended-release (IR/ER) product.

DESIGN

A single open-label study with participants randomly assigned to 2 substudies. Self-selection substudy: participants estimated duration of their last pain episode, then selected ibuprofen IR/ER or standard ibuprofen IR for a similar episode. Compliance substudy: participants purchased and recorded real-world use of ibuprofen IR/ER in daily diaries over 30 days.

SETTING

Eighteen U.S. pharmacies.

PARTICIPANTS

Consumers age 12 years or older who used an average of ≥5 doses per month of an over-the-counter analgesic in the past 3 months.

INTERVENTION

Self-selection: questionnaire only. Compliance: ibuprofen IR/ER as needed.

MAIN OUTCOME MEASURES

Self-selection: percentage who correctly selected or avoided selecting ibuprofen IR/ER based on anticipated pain duration. Compliance: proportion who were excessive users (use for >10 of 30 days and averaging >1600 mg/d, or >20 tablets over ≤10 days and averaging >1600 mg/d).

RESULTS

Self-selection substudy (N = 249): on the primary endpoint, 69.1% (95% confidence interval [CI], 63.3%-74.8%) overall made a correct selection-63.5% (95% CI, 57.5%-69.4%) correctly selected ibuprofen IR/ER for pain ≥6 hours and 5.6% (95% CI, 2.8%-8.5%) correctly avoided selecting ibuprofen IR/ER for shorter-lasting pain. Overall, 82.7% (95% CI, 77.6%-87.8%) chose correctly when subjects who picked ibuprofen IR for pain ≥6 hours (a "missed opportunity," not an incorrect selection) were excluded. Compliance substudy (N = 405): only 5 participants (1.2%; 95% CI, 0.2%-2.3%) were excessive users; all took ibuprofen IR/ER for >10 days, averaging 1821 mg/day (range, 1661.5-2072.7 mg/d). No excessive user experienced an adverse event.

CONCLUSION

Although the study did not meet the a priori primary efficacy outcome target, the majority of participants selected and used ibuprofen 600-mg IR/ER tablets correctly per the labeled instructions.

Single-dose pharmacokinetics of 2 or 3 tablets of biphasic immediate-release/extended-release hydrocodone bitartrate/acetaminophen (MNK-155) under fed and fasted conditions: two randomized open-label trials

Background

Biphasic immediate-release (IR)/extended-release (ER) hydrocodone bitartrate (HB)/acetaminophen (APAP) 7.5/325-mg tablets are formulated with gastroretentive ER drug delivery technology that has been associated with clinically meaningful food effects in other approved products. Two phase 1 studies evaluated potential effects of food on single-dose pharmacokinetics of IR/ER HB/APAP tablets.

Methods

These were single-center, open-label, randomized, single-dose, 3-period crossover studies in healthy volunteers (aged 18–55 years). IR/ER HB/APAP was administered as a single 2-tablet dose (study 1) or 3-tablet dose (study 2) under fed (high- and low-fat) and fasted conditions. Area under the plasma concentration-time curve from 0 h to time t (AUC_0–t) and from time 0 extrapolated to infinity (AUC_0–inf) and maximum observed plasma concentration (C_max) of hydrocodone and APAP under fed versus fasted conditions were compared using analysis of variance. A 90 % confidence interval of the geometric least squares mean ratio fully contained within 80 to 125 % indicated no treatment difference. Safety and tolerability were assessed.

Results

Forty of 48 participants in study 1 and 21 of 30 in study 2 completed all treatments. In both studies, under fed (high- or low-fat meal) versus fasted conditions, 90 % CIs for AUC_0–t and AUC_0–inf for both hydrocodone and APAP were entirely contained within the bioequivalent range (80–125 %), indicating that high- and low-fat meals did not affect the extent of exposure. In both studies, a high-fat meal did not affect the C_max for hydrocodone. Hydrocodone C_max was not affected by a low-fat meal in study 1 but increased by approximately 19 % in study 2. A high-fat meal decreased APAP C_max by approximately 20 % (study 1) and 13 % (study 2); a low-fat meal decreased APAP C_max by 22 % (study 1) and 21 % (study 2). Approximately 50 % of participants in both studies reported ≥1 treatment-emergent adverse event (TEAE), with no notable difference based on food intake. There were no serious or severe AEs. The most common TEAEs were nausea, vomiting, and dizziness.

Conclusions

Pharmacokinetic and safety findings were similar regardless of food intake. TEAEs were consistent with those reported with low-dose combination opioids. IR/ER HB/APAP can be administered without regard to food.

Trial registration

ClinicalTrials.gov NCT02561650 and NCT02561741.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-015-0032-y) contains supplementary material, which is available to authorized users.

Critical appraisal of extended-release hydrocodone for chronic pain: patient considerations

Opioid analgesics are currently the most effective pharmacologic option for the management of both acute and chronic forms of moderate-to-severe pain. Although the "as-needed" use of immediate-release formulations is considered optimum for treating acute, painful episodes of limited duration, the scheduled dosing of extended-release formulations with immediate-release supplementation for breakthrough pain is regarded to be most effective for managing chronic conditions requiring around-the-clock treatment. The recent introduction of extended-release formulations of the opioid analgesic hydrocodone potentially broadened the possibility of providing pain relief for individuals for whom current formulations are either ineffective or not tolerated. However, reaction to the approval of the new formulations has fueled controversy over the general safety and need for opioid medications, in light of their potential for misuse, abuse, diversion, and addiction. Here, we discuss how the approval of extended-release formulations of hydrocodone and the emotionally charged controversy over their release may affect physician prescribing and the care available to patients in need of chronic opioid therapy for the management of pain.

Comparing the Effect of Tampering on the Oral Pharmacokinetic Profiles of Two Extended-Release Oxycodone Formulations with Abuse-Deterrent Properties

OBJECTIVE

Oxycodone DETERx® is an extended-release (ER), microsphere-in-capsule abuse-deterrent-formulation designed to retain its extended-release properties following tampering or misuse (e.g., chewing, crushing). This study assessed the safety and pharmacokinetics of orally administered intact and crushed Oxycodone DETERx® capsules compared with intact and crushed reformulated OxyContin® tablets and crushed immediate-release oxycodone tablets (IR oxycodone).

METHODS

This was a randomized, open-label, active-controlled, cross-over study. Healthy subjects received five oxycodone treatments (40 mg) with a standardized high-fat, high-calorie meal: Oxycodone DETERx® (intact or crushed), OxyContin® (intact or crushed), and IR oxycodone (crushed). Blood samples were collected for assessment of oxycodone plasma concentrations.

RESULTS

Thirty-eight subjects completed the study. Both crushed and intact Oxycodone DETERx® resulted in lower peak plasma concentrations when compared with IR oxycodone. Crushed Oxycodone DETERx® was bioequivalent to intact Oxycodone DETERx® and exhibited a numerically lower Cmax . Also, median Tmax was unchanged by crushing. In contrast, mean peak plasma oxycodone concentrations for crushed OxyContin® were significantly higher compared with intact OxyContin® and were bioequivalent to IR oxycodone. Median Tmax for crushed OxyContin® was the same as IR oxycodone and 3.25 hours shorter than intact OxyContin®.

CONCLUSIONS

These data demonstrate that when crushed and taken orally, Oxycodone DETERx® maintains its EXTENDED-release profile, while crushed OxyContin® shows a pharmacokinetic profile similar to an immediate-release product. These results suggest that Oxycodone DETERx® may be less attractive to illicit drug users compared with existing abuse-deterrent-formulations, while providing a safer option for patients who may unknowingly crush their medication such as those who have difficulty swallowing.

Poloxamer-based binary hydrogels for delivering tramadol hydrochloride: sol-gel transition studies, dissolution-release kinetics, in vitro toxicity, and pharmacological evaluation

In this work, poloxamer (PL)-based binary hydrogels, composed of PL 407 and PL 188, were studied with regard to the physicochemical aspects of sol-gel transition and pharmaceutical formulation issues such as dissolution-release profiles. In particular, we evaluated the cytotoxicity, genotoxicity, and in vivo pharmacological performance of PL 407 and PL 407-PL 188 hydrogels containing tramadol (TR) to analyze its potential treatment of acute pain. Drug-micelle interaction studies showed the formation of PL 407-PL 188 binary systems and the drug partitioning into the micelles. Characterization of the sol-gel transition phase showed an increase on enthalpy variation values that were induced by the presence of TR hydrochloride within the PL 407 or PL 407-PL 188 systems. Hydrogel dissolution occurred rapidly, with approximately 30%-45% of the gel dissolved, reaching ~80%-90% up to 24 hours. For in vitro release assays, formulations followed the diffusion Higuchi model and lower K(rel) values were observed for PL 407 (20%, K(rel) = 112.9 ± 10.6 μg · h(-1/2)) and its binary systems PL 407-PL 188 (25%-5% and 25%-10%, K(rel) =80.8 ± 6.1 and 103.4 ± 8.3 μg · h(-1/2), respectively) in relation to TR solution (K(rel) =417.9 ± 47.5 μg · h(-1/2), P<0.001). In addition, the reduced cytotoxicity (V79 fibroblasts and hepatocytes) and genotoxicity (V79 fibroblasts), as well as the prolonged analgesic effects (>72 hours) pointed to PL-based hydrogels as a potential treatment, by subcutaneous injection, for acute pain.

Patients with chronic pain and dysphagia (CPD): unmet medical needs and pharmacologic treatment options

BACKGROUND

For properly selected patients experiencing chronic pain, extended-release opioid formulations may represent an appropriate pain management choice. For the many adults, elderly, and children who have medical conditions that make swallowing solid, oral-dose formulations difficult (dysphagia) or painful (odynophagia), this option may be limited. The combination of chronic pain with dysphagia (CPD) presents a challenge to physicians and patients alike when oral opioid analgesia is needed to control pain, but patients are unable to swallow solid, oral dosage forms.

METHODS

A Medline search was performed (1990 to 2013) using the search terms swallowing difficulties, dysphagia, odynophagia, adults, pediatrics, elderly, chronic pain, pain, and opioids. The following websites were searched: American Dysphagia Network, Dysphagia Research Society, World Health Organization, American Pain Society, International Association for the Study of Pain, American Academy of Pain Medicine, and American Society of Interventional Pain Physicians. Chronic pain guidelines from the following professional organizations were searched: American Pain Society, National Comprehensive Cancer Network, American Society of Interventional Pain Physicians, British Geriatric Society, European Society of Medical Oncology, World Health Organization, and the European Association for Palliative Care.

FINDINGS

There is an unmet medical need for greater recognition of dysphagia, awareness of potential problems with medication administration in these patients, recognition of alternative drug formulations that are available for use in CPD, and an appreciation that there are new, solid, oral-dose, opioid formulations in development that can mitigate these issues associated with swallowing difficulty while still providing practical, effective analgesia. Current pharmacologic treatments have limitations; new, prospective opioid formulations in clinical development may offer physicians and patients with CPD effective treatment options while mitigating accidental exposure and abuse liability.

CONCLUSIONS

The number of patients with CPD may be larger than is currently anticipated by healthcare providers. Physicians should proactively include a discussion of dysphagia as part of the patient examination. CPD is an unmet medical need. There are novel opioid formulations in clinical development that address the limitations of current opioid treatments. This manuscript reviews the problems associated with dysphagia on medication administration and adherence, currently available treatment options, and opioid analgesic formulations currently in clinical development.

A randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of the extended-release tramadol hydrochloride/acetaminophen fixed-dose combination tablet for the treatment of chronic low back pain

BACKGROUND

Chronic low back pain is a common condition that is often difficult to treat. The combination of tramadol hydrochloride and acetaminophen in an extended-release formulation has been shown to provide rapid and long-lasting analgesic effects resulting from the synergistic activity of these 2 active ingredients.

OBJECTIVE

The goal of this study was to evaluate the efficacy and safety of extended-release tramadol hydrochloride 75-mg/acetaminophen 650-mg fixed-dose combination tablets (TA-ER) for the treatment of chronic low back pain.

METHODS

This Phase III, double-blind, placebo-controlled, parallel-group study enrolled 245 patients with moderate to severe (≥4 cm on a 10-cm visual analog scale) chronic (≥3 months') low back pain insufficiently controlled by previous NSAIDs or cyclooxygenase-2-selective inhibitors and randomly assigned them to receive 4 weeks of either TA-ER or placebo. The primary efficacy end point was the percentage of patients with a pain intensity change rate ≥30% from baseline to final evaluation. Secondary end points included quality of life (Korean Short Form-36), functionality (Korean Oswestry Disability Index), and adverse events.

RESULTS

The percentage of patients with a pain intensity change rate ≥30% was significantly higher (P < 0.05) in the TA-ER group than in the placebo group for both the full analysis set and the per-protocol population. Pain relief success rate from baseline was significantly higher with TA-ER versus placebo at days 8 and 15 but not at the final visit. Patients in the TA-ER group had significant improvements versus placebo in role-physical, general health, and reported health transition domains of the Korean Short Form-36 and significantly higher functional improvements in the personal care section of the Korean Oswestry Disability Index. Patient assessment of overall pain control as "very good" was also significantly higher with TA-ER than with placebo. Adverse events were reported more frequently with TA-ER than with placebo; the most common adverse events reported were nausea, dizziness, constipation, and vomiting.

CONCLUSIONS

TA-ER was significantly more effective than placebo in providing pain relief, functional improvements, and improved quality of life. It exhibited a predictable safety profile in patients with chronic low back pain. ClinicalTrials.gov identifier: NCT01112267.

Update on prescription extended-release opioids and appropriate patient selection

Chronic pain is largely underdiagnosed, often undertreated, and expected to increase as the American population ages. Many patients with chronic pain require long-term treatment with analgesic medications, and pain management may involve use of prescription opioids for patients whose pain is inadequately controlled through other therapies. Yet because of the potential for abuse and addiction, many clinicians hesitate to treat their patients with pain with potentially beneficial agents. Finding the right opioid for the right patient is the first - often complicated - step. Ensuring that patients continue to properly use the medication while achieving therapeutic analgesic effects is the long-term goal. Combined with careful patient selection and ongoing monitoring, new formulations using extended-release technologies incorporating tamper-resistant features may help combat the growing risk of abuse or misuse, which will hopefully reduce individual suffering and the societal burden of chronic pain. The objective of this manuscript is to provide an update on extended-release opioids and to provide clinicians with a greater understanding of which patients might benefit from these new opioid formulations and how to integrate the recommended monitoring for abuse potential into clinical practice.

Primary care considerations of the pharmacokinetics and clinical use of extended-release opioids in treating patients with chronic noncancer pain

Extended-release (ER) opioid analgesics are associated with prolonged analgesia and greater stability in pain relief compared with immediate-release formulations. Due to the pharmacokinetic (PK) characteristics of ER opioids and additional clinical advantages, the use of ER opioids for patients with moderate-to-severe chronic noncancer pain has increased. Primary care physicians are the major prescribers of opioids and require an in-depth understanding of the risks and benefits of opioid treatment in pain management. With appropriate knowledge of PK profiles and clinical outcomes of commonly prescribed ER opioids, primary care physicians can safely and effectively manage this patient population. In addition, the development of ER opioids with abuse-deterrent features marks an important milestone in potentially reducing abuse and may be factored into the clinical decision-making process. This article provides a comprehensive review of the PK and clinical effects of ER opioids and discusses novel ER opioid formulations that may limit abuse potential.

A physician-driven solution--the Association for Medical Ethics, the Physician Payment Sunshine Act, and ethical challenges in pain medicine

The practice of contemporary pain medicine is laced with a number of significant ethical challenges. Considerable difficulties include the overutilization of interventional procedures, the application of under-evidenced treatment modalities, and potentially superfluous opioid prescribing. As with many other fields in medicine, including orthopedic surgery, relationships with industry are both common and pervasive, and influence our medical practice through education, publications, and research. This article highlights these ethical challenges and broaches several physician-driven solutions: The Association for Medical Ethics, the Physicians Payment Sunshine inspired by it, and other non-legislative reforms are discussed.

Effectiveness and safety of tapentadol prolonged release with tapentadol immediate release on-demand for the management of severe, chronic osteoarthritis-related knee pain: results of an open-label, phase 3b study

This open-label, phase 3b study (ClinicalTrials.gov Identifier: NCT00983073) evaluated the effectiveness, and tolerability of tapentadol for severe, chronic osteoarthritis knee pain that was inadequately managed with World Health Organization (WHO) Step I or II analgesics or co-analgesics, or that was not treated with regular analgesics. Prior to starting study treatment, patients discontinued any WHO Step II analgesics, while Step I analgesics and/or co-analgesics were continued at the same dose. Patients received tapentadol prolonged release (50–250 mg bid) during a 5-week titration period and a 7-week maintenance period. Doses of tapentadol immediate release 50 mg (≤twice/day; ≥4 hours apart) were permitted throughout the study (total daily dose of tapentadol prolonged and immediate release, ≤250 mg bid). The primary endpoint was the change in pain intensity on an 11-point numerical rating scale-3 (NRS-3; recalled average pain intensity [11-point NRS] during the last 3 days) from baseline to Week 6, using the last observation carried forward (LOCF) to impute missing pain intensity scores. The mean (standard deviation) change from baseline to Week 6 (LOCF) in pain intensity was −3.4 (2.10; P < 0.0001) for all patients evaluated for effectiveness (n = 195). Significant decreases in pain intensity were also observed at Weeks 6, 8, and 12 (all P < 0.0001) using observed-case analysis. Corresponding significant improvements from baseline to Weeks 6 and 12 were observed in the Western Ontario and McMaster Universities osteoarthritis index, the EuroQol-5 Dimension health status questionnaire, the Short Form-36 health survey, and the Hospital Anxiety and Depression Scale (all P ≤ 0.0103). Treatment-emergent adverse events were in line with those observed in previous studies of tapentadol prolonged release. Overall, the results of this study indicate that tapentadol treatment results in significant improvements in pain intensity, health-related quality of life, and function in patients with inadequately managed, severe, chronic osteoarthritis knee pain.

Effectiveness and safety of tapentadol prolonged release for severe, chronic low back pain with or without a neuropathic pain component: results of an open-label, phase 3b study

OBJECTIVE

This open-label, phase 3b study evaluated the effectiveness and tolerability of tapentadol prolonged release and tapentadol immediate release (for acute pain episodes) for severe, chronic low back pain with or without a neuropathic pain component that was inadequately managed in patients taking World Health Organization (WHO) Step I or II analgesics or who were not regularly treated with analgesics.

RESEARCH DESIGN AND METHODS

Average baseline pain intensity was greater than 5 (11-point numerical rating scale-3 [NRS-3; 3-day average pain intensity]) with WHO Step I or II analgesics and greater than 6 with no regular analgesic regimen. WHO Step II analgesics were discontinued before starting study treatment; WHO Step I analgesics or co-analgesics were continued at the same dose. Patients received tapentadol prolonged release (50-250 mg bid) during a 5-week titration and 7-week maintenance period. Tapentadol immediate release was permitted for acute pain episodes (tapentadol prolonged release and immediate release maximum combined dose, ≤500 mg/day). The painDETECT questionnaire was used to define subsets of patients based on the probability of a neuropathic pain component to their low back pain as 'negative', 'unclear', or 'positive'.

CLINICAL TRIAL REGISTRATION

NCT00983385.

MAIN OUTCOME MEASURE

The primary endpoint was the change from baseline to week 6 in average pain intensity (NRS-3), using the last observation carried forward to impute missing scores.

RESULTS

In the painDETECT negative (n = 49) and unclear/positive (n = 126) subsets, respectively, mean (SD) changes in pain intensity from baseline to week 6 were -2.4 (2.18) and -3.0 (2.07; both p < 0.0001). Among patients who had not received prior WHO Step II treatment, lower doses of tapentadol prolonged release were generally required with increasing likelihood of a neuropathic pain component. Based on the painDETECT questionnaire and the Neuropathic Pain Symptom Inventory (NPSI), tapentadol prolonged release treatment was also associated with significant improvements in neuropathic pain symptoms, with decreases in the number of pain attacks and the duration of spontaneous pain in the last 24 hours in patients with low back pain with a neuropathic pain component (painDETECT unclear or positive score at baseline or screening). The most common treatment-emergent adverse events (incidence ≥10%, n = 176) were nausea, dizziness, headache, dry mouth, fatigue, constipation, diarrhea, nasopharyngitis, and somnolence.

CONCLUSIONS

Tapentadol prolonged release was well tolerated and effective for managing severe, chronic low back pain with or without a neuropathic pain component.

Efficacy and safety of the seven-day buprenorphine transdermal system in opioid-naïve patients with moderate to severe chronic low back pain: an enriched, randomized, double-blind, placebo-controlled study

CONTEXT

This article presents the results of a pivotal Phase 3 study that assesses a new treatment for the management of chronic low back pain: a transdermal patch containing the opioid buprenorphine. In this randomized, placebo-controlled study with an enriched enrollment design, the buprenorphine transdermal system (BTDS) was found to be efficacious and generally well tolerated.

OBJECTIVES

This enriched, multicenter, randomized, double-blind study evaluated the efficacy, tolerability, and safety of BTDS in opioid-naïve patients who had moderate to severe chronic low back pain.

METHODS

Patients who tolerated and responded to BTDS (10 or 20 mcg/hour) during an open-label run-in period were randomized to continue BTDS 10 or 20 mcg/hour or receive matching placebo. The primary outcome was "average pain over the last 24 hours" at the end of the 12-week double-blind phase, collected on an 11-point scale (0=no pain, 10=pain as bad as you can imagine). Sleep disturbance (Medical Outcomes Study subscale) and total number of supplemental analgesic tablets used were secondary efficacy variables.

RESULTS

Fifty-three percent of patients receiving open-label BTDS (541 of 1024) were randomized to receive BTDS (n=257) or placebo (n=284). Patients receiving BTDS reported statistically significantly lower pain scores at Week 12 compared with placebo (least square mean treatment difference: -0.58, P=0.010). Sensitivity analyses of the primary efficacy variable and results of the analysis of secondary efficacy variables supported the efficacy of BTDS relative to placebo. During the double-blind phase, the incidence of treatment-emergent adverse events was 55% for the BTDS treatment group and 52% for the placebo treatment group. Laboratory, vital sign, and electrocardiogram evaluations did not reveal unanticipated safety findings.

CONCLUSION

BTDS was efficacious in the treatment of opioid-naïve patients with moderate to severe chronic low back pain. Most treatment-emergent adverse events observed were consistent with those associated with the use of opioid agonists and transdermal patches.

Opioid analgesics and the risk of fractures in older adults with arthritis

OBJECTIVES

To compare the risk of fracture associated with initiating opioids with that of nonsteroidal anti-inflammatory drugs (NSAIDs) and the variation in risk according to opioid dose, duration of action, and duration of use.

DESIGN

Retrospective cohort study.

SETTING

Two statewide pharmaceutical benefit programs for persons aged 65 and older.

PARTICIPANTS

Twelve thousand four hundred thirty-six initiators of opioids and 4,874 initiators of NSAIDs began treatment between January 1, 1999, and December 31, 2006. Mean age at initiation of analgesia was 81; 85% of participants were female, and all had arthritis.

MEASUREMENTS

Cox proportional hazards models, adjusted for several potential confounders, quantified fracture risk. Study outcomes were fractures of the hip, humerus or ulna, or wrist, identified using a combination of diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification) and procedure (Common Procedural Terminology) codes.

RESULTS

There were 587 fracture events among the participants initiating opioids (120 fractures per 1,000 person-years) and 38 fracture events among participants initiating NSAIDs (25 fractures per 1,000 person-years) (hazard ratio (HR)=4.9, 95% confidence interval (CI)=3.5-6.9). Fracture risk was greater with higher opioid dose. Risk was greater for short-acting opioids (HR=5.1, 95% CI=3.7-7.1) than for long-acting opioids (HR=2.6, 95% CI=1.5-4.4), even in participants taking equianalgesic doses, with differential fracture risk apparent for the first 2 weeks after starting opioids but not thereafter.

CONCLUSION

Older people with arthritis who initiate therapy with opioids are more likely to experience a fracture than those who initiate NSAIDs. For the first 2 weeks after initiating opioid therapy, but not thereafter, short-acting opioids are associated with a greater risk of fracture than are long-acting opioids.

Use of opioids in long-term management of temporomandibular joint dysfunction

The long-term treatment of patients with chronic temporomandibular joint dysfunction has been challenging. The long-term use of opioids in these patients can be neither supported nor refuted based on current evidence. However, evidence is available to support the long-term use of opioids in other chronic noncancer pain states with reduced pain, improved function, and improved quality of life. One group of patients with chronic temporomandibular joint pain, for whom both noninvasive and invasive treatment has failed, might benefit from long-term opioid medication. The choices include morphine, fentanyl, oxycodone, tramadol, hydrocodone, and methadone. Adjunct medication, including antidepressant and anticonvulsant drugs, can also be used. The safety of these medications has been well established, but the potential for adverse drug-related behavior does exist, requiring appropriate patient selection, adequate monitoring, and intervention when needed.

The course of opioid prescribing for a new episode of disabling low back pain: opioid features and dose escalation

Despite utilization concerns, little information is available on opioid prescribing for acute, disabling low back pain (LBP) and how opioid features (purity, strength, and length of action) and dose change over time. This information is important in targeting guideline implementation efforts and identifying risks for inappropriate prescribing. Using 2002-2003 United States' workers compensation claims, a cohort of 2868 cases with a new episode of work-related LBP and at least one opioid prescription was followed for 2 years. Opioid prescriptions (timing, dose, and formulation), demographics, and medical data were captured. A longitudinal model of change was used to evaluate factors associated with dosing changes. Opioid prescribing typically began early in the course of care (median=8 days, Inter-Quartile Range (IQR)=3, 43 days) and was often prolonged (median=46 days, IQR=14, 329). At the end of the observation period, 7.1% of non-surgical cases and 30.6% of surgical cases were still receiving opioids. The number of days between the initial LBP report and the first opioid prescription had the greatest association with subsequent dose escalation. Dose escalation was greater with pure formulations, and was not related to clinical severity or surgery. In contrast to previous and current guideline recommendations, opioid prescribing for acute LBP was often prolonged, and longer for surgical cases. These results reinforce recommendations to limit opioid duration, and suggest that consideration of opioid features, purity as an important one, can be part of a strategy to prevent escalating dosages.

Risks for possible and probable opioid misuse among recipients of chronic opioid therapy in commercial and medicaid insurance plans: The TROUP Study

The use of chronic opioid therapy (COT) for chronic non-cancer pain (CNCP) has increased dramatically in the past two decades. There has also been a marked increase in the abuse of prescribed opioids and in accidental opioid overdose. Misuse of prescribed opioids may link these trends, but has thus far only been studied in small clinical samples. We therefore sought to validate an administrative indicator of opioid misuse among large samples of recipients of COT and determine the demographic, clinical, and pharmacological risks associated with possible and probable opioid misuse. A total of 21,685 enrollees in commercial insurance plans and 10,159 in Arkansas Medicaid who had at least 90 days of continuous opioid use 2000-2005 were studied for one year. Criteria were developed for possible and probable opioid misuse using administrative claims data concerning excess days supplied of short-acting and long-acting opioids, opioid prescribers and opioid pharmacies. We estimated possible misuse at 24% of COT recipients in the commercially insured sample and 20% in the Medicaid sample and probable misuse at 6% in commercially insured and at 3% in Medicaid. Among non-modifiable factors, younger age, back pain, multiple pain complaints and substance abuse disorders identify patients at high risk for misuse. Among modifiable factors, treatment with high daily dose opioids (especially >120 mg MED per day) and short-acting Schedule II opioids appears to increase the risk of misuse. The consistency of the findings across diverse patient populations and the varying levels of misuse suggest that these results will generalize broadly, but await confirmation in other studies.

Synthesis of 14-alkoxymorphinan derivatives and their pharmacological actions

Among opioids, morphinans play an important role as therapeutically valuable drugs. They include pain relieving agents such as naturally occurring alkaloids (e.g. morphine, codeine), semisynthetic derivatives (e.g. oxycodone, oxymorphone, buprenorphine), and synthetic analogs (e.g. levorphanol). Currently used opioid analgesics also share a number of severe side effects, limiting their clinical usefulness. The antagonist morphinans, naloxone and naltrexone are used to treat opioid overdose, opioid dependence, and alcoholism. All these opioid drugs produce their biological actions through three receptor types, mu, delta, and kappa, belonging to the G-protein-coupled receptor family. Considerable effort has been put forward to understand the appropriate use of opioid analgesics, while medicinal chemistry and opioid pharmacology have been continuously engaged in the search for safer, more efficacious and nonaddicting opioid compounds, with the final goal to reduce complications and to improve patient compliance. Toward this goal, recent advances in chemistry, ligand-based structure activity relationships and pharmacology of 14-alkoxymorphinans are reviewed in this chapter. Current developments of different structural patterns of 14-alkoxymorphinans as research tools and their potential therapeutic opportunities are also summarized.

Dosing protocol and analgesic efficacy determine opioid tolerance in the mouse

RATIONALE

Analgesic efficacy of opioids and dosing protocol have been shown to influence analgesic tolerance.

OBJECTIVE

This study tested the hypothesis that there is an inverse relationship between analgesic efficacy and tolerance following continuous infusion of opioid analgesics. Furthermore, it was hypothesized that analgesic efficacy plays a minor role in determining the magnitude of tolerance following intermittent or acute administration, and that acute and intermittent administration of opioid agonists produces less tolerance than continuous infusion.

MATERIALS AND METHODS

Analgesic (tailflick) efficacy (tau) of etorphine, methadone, oxycodone, and hydrocodone was determined using the operational model of agonism. To induce tolerance, mice were injected with opioid agonists once (acute), once per day for 7 days (intermittent) or continuously infused for 7 days. Dose-response studies were conducted using morphine following treatment.

RESULTS

The order of analgesic efficacy was etorphine > methadone > oxycodone congruent with hydrocodone. Infusion of the higher analgesic efficacy drug etorphine produced significantly less tolerance than the lower analgesic efficacy drugs oxycodone, methadone, and hydrocodone at equi-effective doses. In general, intermittent and acute treatment produced less tolerance compared to continuous infusion even at similar daily doses.

CONCLUSION

Taken together, intermittent and acute opioid agonist administration produces minimal tolerance compared to continuous infusion. Furthermore, there is an inverse relationship between analgesic efficacy and tolerance following continuous infusion. These results suggest that opioid analgesic tolerance may be increased when sustained release dosing formulations or continuous infusions are employed clinically.

Behavioral models of pain states evoked by physical injury to the peripheral nerve

Physical injury or compression of the root, dorsal root ganglion, or peripheral sensory axon leads to well-defined changes in biology and function. Behaviorally, humans report ongoing painful dysesthesias and aberrations in function, such that an otherwise innocuous stimulus will yield a pain report. These behavioral reports are believed to reflect the underlying changes in nerve function after injury, wherein increased spontaneous activity arises from the neuroma and dorsal root ganglion and spinal changes increase the response of spinal projection neurons. These pain states are distinct from those associated with tissue injury and pose particular problems in management. To provide for developing an understanding of the underlying mechanisms of these pain states and to promote development of therapeutic agents, preclinical models involving section, compression, and constriction of the peripheral nerve or compression of the dorsal root ganglion have been developed. These models give rise to behaviors, which parallel those observed in the human after nerve injury. The present review considers these models and their application.