The use of long-acting opioids in chronic pain management

Co-delivery of an HIV prophylactic and contraceptive using PGSU as a long-acting multipurpose prevention technology

OBJECTIVES

Poly(glycerol sebacate) urethane (PGSU) elastomers formulated with 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA), levonorgestrel (LNG), or a combination thereof can function as multipurpose prevention technology implants for prophylaxis against HIV and unintended pregnancies. For these public health challenges, long-acting drug delivery technologies may improve patient experience and adherence. Traditional polymers encounter challenges delivering multiple drugs with dissimilar physiochemical properties. PGSU offers an alternative option that successfully delivers hydrophilic EFdA alongside hydrophobic LNG.

METHODS

This article presents the formulation, design, and characterization of PGSU implants, highlighting the impact of API loading, dimensions, and individual- versus combination-loading on release rates.

RESULTS

Co-delivery of hydrophilic EFdA alongside hydrophobic LNG acted as a porogen to accelerate LNG release. Increasing the surface area of LNG-only implants increased LNG release. All EFdA-LNG, EFdA-only, and LNG-only formulated implants demonstrated low burst release and linear release kinetics over 245 or 122 days studied to date.

CONCLUSION

PGSU co-delivers two APIs for HIV prevention and contraception at therapeutically relevant concentrations in vitro from a single bioresorbable, elastomeric implant. A new long-acting polymer technology, PGSU demonstrates linear-release kinetics, dual delivery of APIs with disparate physiochemical properties, and biocompatibility through long-term subcutaneous implantation. PGSU can potentially meet the demands of complex MPT or fixed-dose combination products, where better solutions can serve and empower patients.

Opioid prescribing practice standard in British Columbia, Canada: Rationale, controversies, and directions

British Columbia (BC) has been the hardest hit province in Canada's ongoing overdose epidemic. As part of the province-level response, the College of Physicians and Surgeons of British Columbia (CPSBC) implemented the "Safe Prescribing of Drugs with Potential for Misuse/Diversion" practice standard in June 2016. The practice standard established specific dose and quantity thresholds for opioid prescribing as professional and ethical conduct expectations for physicians in BC. This supply side intervention was based on expert interpretation of available evidence of non-superiority of opioid treatments to non-opioid treatments. However, the potential for misinterpretation of dosage ceiling thresholds and the negative repercussions to patients that could follow raised concerns among both physicians and patients. We provide a comprehensive overview of the rationale, early impact, controversies, and potential shortcomings of the CPSBC's practice standard.

Regular dosing compared with as-needed dosing of opioids for management of chronic cancer pain: systematic review and meta-analysis

Opioids are the recommended form of analgesia for patients with persistent cancer pain, and regular dosing "by the clock" is advocated in many international guidelines on cancer pain management. The development of sustained-release opioid preparations has made regular dosing easier for patients. However, patients report that the intensity and impact of their cancer pain varies considerably day to day, and many try to find a trade-off between acceptable pain control and impact of cognitive (and other) adverse effects on daily activities. In acute care settings, (eg, postoperative) as-needed dosing and other opioid-sparing approaches have resulted in better patient outcomes compared with regular dosing. The aim of this study was to determine whether regular dosing of opioids was superior to as-needed dosing for persistent cancer pain. We systematically searched for randomised controlled trials that directly compared pain outcomes from regular dosing of opioids with as-needed dosing in adult cancer patients. We identified 4347 records, 25 randomised controlled trials meet the inclusion criteria, 9 were included in the review, and 7 of these included in meta-analysis. We found no clear evidence demonstrating superiority of regular dosing of opioids compared with as-needed dosing in persistent cancer pain, and regular dosing was associated with significantly higher total opioid doses. There was, however, a paucity of trials directly answering this question, and low-quality evidence limits the conclusions that can be drawn. It is clear that further high-quality clinical trials are needed to answer this question and to guide clinical practice.

Cognitive Behavioral Therapy for Chronic Pain-One Therapeutic Approach for the Opioid Epidemic

Opioids are frequently prescribed for chronic pain. For the past 2 decades, long-term opioid analgesic therapy was considered the cornerstone of effective pain management for chronic nonmalignant conditions, despite a lack of documented effectiveness and safety, with the attendant risk of addiction, overdose, and death. Cognitive behavioral therapy (CBT) may be used effectively to treat chronic pain, either as a stand-alone treatment or with other nonopioid pharmacological treatments. CBT improves pain-related outcomes along with mobility, quality of life, and disability and mood outcomes. Compared with long-term use of opioids, CBT has dramatically lower risks and may therefore be worth pursuing.

Multi-system state shifts and cognitive deficits induced by chronic morphine during abstinence

Chronic morphine administration induces neural plasticity followed by withdraw. And clinic observation indicates that obvious cognitive deficits are found during withdrawal. However, current neural substrates that regulate dysfunction in withdrawal are unknown. In our studies, chronic morphine administration was used to induce the spontaneous withdrawal model in rats. A series of cognitive abilities was tested to explore brain function. To further evaluate the neural substrates of dysfunction, Manganese-enhanced MRI(MEMRI) was used to map the dysfunctional regions in vivo.We observed that chronic morphine administration could induce obvious withdrawal behaviors in abstinence followed by cognitive impairments, such as impairments in working memory, reward, interaction and enhancement of anxiety. Our in-vivo MEMRI data using the voxel-wise comparisons showed that the manganese-enhanced signal intensity (VMI) within morphine withdrawal groups was increased in cingulate cortex (Cg), secondary motor cortex (M2), CA3 subfield of hippocampus, dorsal striatum (D-striatum), retrosplenial cortex (RS), shell subregion of NAc (AcbSh), core subregion of NAc (AcbC), central nucleus of amygdala (CeC), basolateral amygdaloid nucleus (BLA), central amygdaloid nucleus (CeM), anterior hypothalamic area, central (AHC), ventral tegmental area (VTA) and scaphoid thalamic nucleus (SC).However, decreasing of VMI was found in the ventrolateral striatum (V-striatum) and lateral posterior thalamic nucleus (LP) compared to the control group. These brain regions were beleived to be components of the memory, executive, limbic and regulatory systems. Therefore, our present studies indicate that withdrawal induced by chronic morphine adiministration could disturb brain function leading to multi-systems state shifts and cognitive deficits in abstinence.

Rationally designed benzopyran fused isoxazolidines and derived β2,3,3-amino alcohols as potent analgesics: Synthesis, biological evaluation and molecular docking analysis

Based on structure activity analysis of morphine related opiates, we have synthesized some novel benzopyran fused isoxazolidines (2a-e) and derived conformationally constrained β^2,3,3-amino alcohols (3a-e), which were evaluated in vivo for their anti-nociceptive activity through acetic acid induced writhing test (peripheral) and formalin induced algesia (central). Results showed that, compound 2a possesses significant opioid agonist activity. Further, molecular docking analysis reveals that compound 2a binds to δ-opioid receptor (DOR) with comparatively better D-score than to μ (MOR) and κ (KOR) receptors. Compound 2a did not show any toxicity up to a 2000 mg kg^-1 dose.

Evaluation of the durability of pain relief throughout a 12 hour dosing interval of a novel, extended-release, abuse-deterrent formulation of oxycodone

BACKGROUND

Abuse deterrent formulations (ADF) are designed to prevent the misuse of opioids by tampering (e.g. physical and chemical manipulation) in order to ingest the opioid in a manner other than intended. Extended-release (ER) formulations are formulated with a larger drug load than immediate-release (IR) formulations, which makes ER opioids more desirable to drug abusers than I.R. formulations. ADFs, therefore, are particularly useful with ER opioid agents, which are designed to produce consistent analgesia over prolonged dosing intervals. However, the drug release properties of these formulations vary and sometimes may not provide adequate pain relief throughout the intended dosing interval, requiring patients to take additional medication for pain relief. Oxycodone DETERx* (Xtampza ER * ) is a novel, microsphere-in-capsule opioid formulation, which allows for twice daily dosing (i.e. every 12 hours) and mitigates the ability to tamper with the formulation.

OBJECTIVE

To evaluate the durability of pain relief of a novel formulation of oxycodone throughout the 12 hour dosing interval.

RESEARCH DESIGN AND METHODS

This study is a post-hoc analysis of 193 subjects in a Phase 3 randomized withdrawal, double-blind, placebo-controlled, enriched-enrollment, parallel-group, multicenter, 12-week clinical study.

MAIN OUTCOME MEASURES

The analysis evaluated the frequency and distribution of use of oxycodone ER and rescue medication during the Double-blind Maintenance Phase of the study.

RESULTS

Usage patterns captured by an electronic diary indicated limited overall and limited per-day use of rescue medication with no increase in rescue medication consumption 8 to 12 hours post-dose, suggesting that subjects did not experience end-of-dose failure during this time period.

LIMITATIONS

This study is limited in that it is a post-hoc analysis based on data gathered electronically from a large, prospective, double-blind, randomized, placebo-controlled, Phase 3 clinical study.

CONCLUSION

The evaluation of dosing patterns indicates that this ER oxycodone capsule formulation has durability of effect over the entire 12-hour dosing interval. These data support the use of abuse-deterrent oxycodone ER as a 12-hour dosing formulation.

Exploring the lived experience of adults using prescription opioids to manage chronic noncancer pain

BACKGROUND

Chronic noncancer pain (CNCP) and prescription opioid use is a highly complex and growing health care issue in Canada. Many quantitative research studies have investigated the effectiveness of opioids for chronic pain; however, gaps remain in the literature regarding the personal experience of using opioids and their impact on those experiencing CNCP.

OBJECTIVE

To explore the lived experience of adults using prescription opioids to manage CNCP, focusing on how opioid medication affected their daily lives.

METHODS

In-depth qualitative interviews were conducted with nine adults between 40 and 68 years of age who were using prescription opioids daily for CNCP. Interviews were audiorecorded and transcribed, and subsequently analyzed using interpretive phenomenological analysis.

RESULTS

Six major themes identified positive and negative aspects of opioid use associated with social, physical, emotional and psychological dimensions of pain management. These themes included the process of decision making, and physical and psychosocial consequences of using opioids including pharmacological side effects, feeling stigmatized, guilt, fears, ambivalence, self-protection and acceptance.

CONCLUSION

Although there were many negative aspects to using opioids daily, the positive effects outweighed the negative for most participants and most of the negative aspects were socioculturally induced rather than caused by the drug itself. The present study highlighted the complexities involved in using prescription opioids daily for management of CNCP for individuals living with pain.

Highlights in opioid agonists and antagonists

This review highlights new insights in to opioid agonists and antagonists, focusing on their mechanism of action with spinal and systemic administration, chronic use and main adverse effects. Short-cuts on some opioid agonists and antagonists of clinical interest are also presented, revealing potential clinical implications and future clinical directions as part of multimodal analgesia.

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.

A Phase IIIb, Multicentre, Randomised, Parallel-Group, Placebo-Controlled, Double-Blind Study to Investigate the Efficacy and Safety of OROS Hydromorphone in Subjects with Moderate-to-Severe Chronic Pain Induced by Osteoarthritis of the Hip or the Knee

Background. Opioid analgesics are included in treatment guidelines for the symptomatic management of osteoarthritis (OA). Starting with a low dose of opioid and slowly titrating to a higher dose may help avoid intolerable side effects. Methods. Subjects aged ≥40 years, with moderate to severe pain induced by OA of the hip or knee not adequately controlled by previous non-steroidal anti-inflammatory drugs (NSAIDs) or paracetamol treatment, were enrolled. Subjects received OROS hydromorphone 4 mg or placebo once-daily. The dose was titrated every 3-4 days in case of unsatisfactory pain control during the 4-week titration phase. A 12 week maintenance phase followed. The primary efficacy endpoint was the change in "pain on average" measured on the Brief Pain Inventory (BPI) scale from baseline to the end of the maintenance phase. Results. 139 subjects received OROS hydromorphone and 149 subjects received placebo. All efficacy endpoints showed similar improvements from baseline to end of study in the 2 groups. The safety results were consistent with the safety profile of OROS hydromorphone. Conclusion.The study did not meet the primary endpoint; although many subjects' pain was not adequately controlled at inclusion, their pain may have improved with continued paracetamol or NSAID treatment.

The use of algorithms in assessing and managing persistent pain in older adults

OVERVIEW

As the U.S. population ages, nurses will care for increasing numbers of older adults, most of whom suffer from at least one chronic illness. The persistent pain associated with many chronic illnesses can have detrimental effects on patients' functioning and quality of life. Algorithms developed from evidence-based clinical practice guidelines are tools that can facilitate the application of research to practice. This article introduces readers to the use of algorithms in guiding the assessment and management of persistent pain in older adults, and provides an illustrative case study.

Chronic pain management issues in the primary care setting and the utility of long-acting opioids

IMPORTANCE OF THE FIELD

Chronic/persistent pain - a highly prevalent condition that places a substantial burden on patients in terms of personal suffering, reduced productivity and health care costs - remains inadequately treated in many patients. The purpose of this review is to provide an overview and evaluate the burden and undertreatment of chronic/persistent pain, considerations for choosing an analgesic and the utility of long-acting opioids.

AREAS COVERED IN THIS REVIEW

A PubMed search was conducted to identify randomized, placebo-controlled trials evaluating the efficacy and safety of long-acting opioids in chronic pain conditions. The following search terms were used: long-acting opioids, extended-release opioids, controlled-release opioids, sustained-release opioids, and transdermal opioids. The search was limited to randomized, controlled trials published within the last 10 years (1998 - 2008). Studies meeting the following criteria were excluded from review: those focused on a neuropathic pain condition or specific patient subpopulations (e.g., opioid-experienced patients); those conducted outside the USA; and those evaluating a long-acting opioid that is not on the US market at present.

WHAT THE READER WILL GAIN

The reader will first develop a better understanding of the individual and societal ramifications of undertreated chronic pain. Then, a critical review of safety and efficacy data from well-controlled randomized studies will help readers understand the choices and variables that should be considered when selecting appropriate treatments for patients with chronic pain.

TAKE HOME MESSAGE

Successful management of chronic/persistent pain should be individually tailored to each patient, taking into account his or her pain intensity and duration, disease state, tolerance of adverse events and risk of medication abuse or diversion. The literature supports the efficacy and safety of a number of long-acting opioids for the treatment of moderate to severe chronic pain, demonstrating sustained improvements in pain intensity and pain-related sleep disturbances with these agents.

Risks for opioid abuse and dependence among recipients of chronic opioid therapy: results from the TROUP study

OBJECTIVE

To estimate the prevalence of and risk factors for opioid abuse/dependence in long-term users of opioids for chronic pain, including risk factors for opioid abuse/dependence that can potentially be modified to decrease the likelihood of opioid abuse/dependence, and non-modifiable risk factors for opioid abuse/dependence that may be useful for risk stratification when considering prescribing opioids.

METHODS

We used claims data from two disparate populations, one national, commercially insured population (HealthCore) and one state-based, publicly insured (Arkansas Medicaid). Among users of chronic opioid therapy, we regressed claims-based diagnoses of opioid abuse/dependence on patient characteristics, including physical health, mental health and substance abuse diagnoses, sociodemographic factors, and pharmacological risk factors.

RESULTS

Among users of chronic opioid therapy, 3% of both the HealthCore and Arkansas Medicaid samples had a claims-based opioid abuse/dependence diagnosis. There was a strong inverse relationship between age and a diagnosis of opioid abuse/dependence. Mental health and substance use disorders were associated with an increased risk of opioid abuse/dependence. Effects of substance use disorders were especially strong, although mental health disorders were more common. Concerning opioid exposure; lower days supply, lower average doses, and use of Schedule III-IV opioids only, were all associated with lower likelihood of a diagnosis of opioid abuse/dependence.

CONCLUSION

Opioid abuse and dependence are diagnosed in a small minority of patients receiving chronic opioid therapy, but this may under-estimate actual misuse. Characteristics of the patients and of the opioid therapy itself are associated with the risk of abuse and dependence.

Extended-release morphine sulfate in treatment of severe acute and chronic pain

Morphine is the archetypal opioid analgesic. Because it is a short-acting opioid, its use has been limited to the management of acute pain. The development of extended-release formulations have resulted in the increased utilization of morphine in chronic pain conditions. This review documents the history of morphine use in pain treatment, and describes the metabolism, pharmacodynamics, formulations, and efficacy of the currently available extended-release morphine medications.

The role of tramadol ER in the treatment of chronic pain

Despite its high prevalence, chronic pain is suboptimally treated in approximately one half of affected patients. Failure to recognise and manage comorbid physical and psychosocial impairments may contribute to the perpetuation of chronic pain. Knowledge of the potential advantages and disadvantages of available analgesic medications will permit informed selection of the appropriate medication for the individual chronic pain patient. Ultimate therapeutic goals will also influence analgesic medication selection. For the patient with chronic pain requiring analgesic treatment for an extended period of time, long-acting analgesics are recommended. Theoretically, these agents will provide sustained analgesia by minimising the end-of-dose pain that is often seen with short-acting medications, with improved patient convenience and a potential for reduced risk of adverse events. The extended-release formulation of tramadol (tramadol ER) has proven efficacy in chronic pain conditions such as osteoarthritis and low back pain, as well as a favourable tolerability profile. In addition, tramadol ER has been shown in clinical trials to improve pain-related sleep disturbances and physical function in patients with chronic pain from osteoarthritis and low back pain.

Transdermal buprenorphine - a critical appraisal of its role in pain management

This paper reviews the current clinical data for the role of transdermal buprenorphine (BUP TDS) in the treatment of diverse acute and chronic pain syndromes. Literature searches were carried out using PubMed (1988 to June 2009). The published findings seem to support hypotheses regarding the rather unique analgesic mechanisms of buprenorphine as compared with pure μ-opioids like morphine and fentanyl. However, the exact mechanism of this analgesic efficacy still remains largely unknown despite recent advances in preclinical pharmacological studies. Such assessments have demonstrated the sustained antihyperalgesic effect of buprenorphine in diverse animal pain models. These findings are supported in a growing number of clinical studies of oral, intrathecal, intravenous, and Bup TDS. This review paper focuses almost entirely on the clinical experience concerning the transdermal administration of buprenorphine, although preclinical aspects are also addressed in order to provide a complete picture of the unique pharmacological properties of this analgesic drug. Mounting evidence indicates the appropriateness of Bup TDS in the treatment of diverse acute and chronic pain syndromes which have been less or not responsive to other opioids. Additionally, BUP TDS seems to hold great promise for other difficult-to-treat (pain) conditions, such as patients in the intensive care setting. However, its use is somewhat tempered by the occurrence of local skin reactions which have been shown to be often therapy resistant. Further studies are certainly warranted to identify even more precisely the clinical syndromes that are most sensitive to buprenorphine treatment, and to compare buprenorphine to other opioids in head-to-head trials of acute and chronic pain conditions.

A comparison of long- and short-acting opioids for the treatment of chronic noncancer pain: tailoring therapy to meet patient needs

Management of chronic noncancer pain (CNCP) requires a comprehensive assessment of the patient, the institution of a structured treatment regimen, an ongoing reassessment of the painful condition and its response to therapy, and a continual appraisal of the patient's adherence to treatment. For many patients with CNCP, the analgesic regimen will include opioids. Physicians should consider the available evidence of efficacy, the routes of administration, and the pharmacokinetics and pharmacodynamics of the various formulations as they relate to the temporal characteristics of the patient's pain. When making initial decisions, physicians should decide whether to prescribe a short-acting opioid (SAO) with a relatively quick onset of action and short duration of analgesic activity, a long-acting opioid (LAO) with a longer duration of analgesic action but a potentially longer onset of action, or both. Studies suggest that SAOs and LAOs are both effective for most types of CNCP. A review of published studies found no data to suggest that either SAOs or LAOs are generally more efficacious for treating any particular CNCP condition. The LAOs may provide more stable analgesia with less frequent dosing; however, opioid therapy should be tailored to the pain state and the individual patient, and SAOs may be appropriate for some patients with CNCP. MEDLINE and PubMed searches were conducted to locate relevant studies published from January 1975 to April 2008 using the following search terms: opioids, short-acting opioids, long-acting opioids, chronic pain, chronic pain AND opioids, and narcotics. English-only randomized controlled trials and nonrandomized studies were considered.

Opioids switching with transdermal systems in chronic cancer pain

Background

Due to tolerance development and adverse side effects, chronic pain patients frequently need to be switched to alternative opioid therapy

Objective

To assess the efficacy and tolerability of an alternative transdermally applied (TDS) opioid in patients with chronic cancer pain receiving insufficient analgesia using their present treatment.

Methods

A total of 32 patients received alternative opioid therapy, 16 were switched from buprenorphine to fentanyl and 16 were switched from fentanyl to buprenorphine. The dosage used was 50% of that indicated in equipotency conversion tables. Pain relief was assessed at weekly intervals for the next 3 weeks

Results

Pain relief as assessed by VAS, PPI, and PRI significantly improved (p < 0.0001) in all patients at all 3 follow up visits. After 3 weeks of treatment, the reduction in the mean VAS, PPI, and PRI scores in the fentanyl and buprenorphine groups was 68, 77, 74, and 69, 79, and 62%, respectively. Over the same time period the use of oral morphine as rescue medication was reduced from 27.5 ± 20.5 (mean ± SD) to 3.75 ± 8.06, and 33.8 ± 18.9 to 3.75 ± 10.9 mg/day in the fentanyl and buprenorphine groups, respectively. There was no significant difference in either pain relief or rescue medication use between the two patient groups The number of patient with adverse events fell during the study. After the third week of the treatment the number of patients with constipation was reduced from 11 to 5, and 10 to 4 patients in the fentanyl and buprenorphine groups, respectively. There was a similar reduction in the incidence of nausea and vomiting. No sedation was seen in any patient after one week of treatment.

Conclusion

Opioid switching at 50% of the calculated equianalgesic dose produced a significant reduction in pain levels and rescue medication. The incidence of side effects decreased and no new side effects were noted. Further studies are required to provide individualized treatment for patients according to their different types of cancer.

Poderia a atividade física induzir analgesia em pacientes com dor crônica?

A dor crônica caracteriza-se pela persistência do sintoma além do período fisiológico de recuperação do tecido lesado. Essas dores causam incapacidade física e redução da performance cognitiva, reduzem a qualidade de vida e o bem-estar dos pacientes, cujo tratamento proposto contradiz o clássico binômio da terapia da dor aguda (repouso e fármacos). Para a dor crônica prescrevem-se exercícios físicos e sugerem-se tratamentos multidisciplinares. Embora a atividade física seja prescrita há mais de 20 anos, os mecanismos neurofisiológicos envolvidos ainda não são compreendidos. Descrevemos brevemente os mecanismos endógenos de controle da dor crônica e evidências da literatura científica que defendem o sistema opioide como mecanismo de ação na analgesia induzida pelo exercício em indivíduos sadios e atletas. Esse mecanismo também parece agir na população com dor crônica, embora haja controvérsias. Finalizamos o artigo com considerações clínicas para a prescrição do exercício para a população com dor crônica.

The value of CYP2D6 and OPRM1 pharmacogenetic testing for opioid therapy

In managing pain, clinicians working with the more than 80 million people in the United States who suffer annually from serious pain face decisions about choosing the most appropriate pharmacologic agent, to contemplating nonpharmacologic modalities. This article focuses on opioid use for pain management, their risks of toxicity and addiction, adverse reactions, undertreatment for fear of addiction, and integration of novel diagnostics, such as the pharmacogenetic biomarkers CYP2D6 and OPRM1 as holding promise for assessing a patient's risk of adverse events or likelihood of efficacy. Incorporation of such biomarkers is emerging on the forefront of personalized medicine, and has the potential to dramatically improve the utility and efficacy of both current and future pain management strategies.

Sleep as a marker in the effective management of chronic osteoarthritis pain with opioid analgesics

OBJECTIVES

Sleep disturbances frequently accompany chronic pain from osteoarthritis (OA), and their effective management may reflect successful treatment of chronic pain. The objective of this article is to provide a rationale for using improvement in sleep as a marker for effective management of chronic OA pain with opioid analgesics. For this purpose, available evidence evaluating the relationship between successful management of chronic pain with opioids and improvements in sleep in patients with OA is reviewed.

METHODS

We conducted a comprehensive PubMed search to identify studies that systematically measured the impact of opioid treatment on pain and sleep parameters in the context of chronic pain from OA. Our search criteria included publication in a recognized peer-reviewed journal, randomized placebo-controlled design, and assessment of both pain intensity and sleep as outcomes.

RESULTS

In each of the 10 placebo-controlled studies identified, concurrent improvements in pain intensity and measured sleep disturbances were observed in patients receiving the long-acting opioid analgesics under study. Improved overall sleep quality, reduced awakenings from pain, and increased duration of sleep were among the favorable changes observed in patients with OA treated with long-acting opioids.

CONCLUSIONS

Current evidence suggests that various long-acting opioid analgesics simultaneously achieve pain control and improve sleep. However, the complex interaction between reduced pain and improved sleep requires further study.

Opioids and the treatment of chronic pain: controversies, current status, and future directions

Opioids have been regarded for millennia as among the most effective drugs for the treatment of pain. Their use in the management of acute severe pain and chronic pain related to advanced medical illness is considered the standard of care in most of the world. In contrast, the long-term administration of an opioid for the treatment of chronic noncancer pain continues to be controversial. Concerns related to effectiveness, safety, and abuse liability have evolved over decades, sometimes driving a more restrictive perspective and sometimes leading to a greater willingness to endorse this treatment. The past several decades in the United States have been characterized by attitudes that have shifted repeatedly in response to clinical and epidemiological observations, and events in the legal and regulatory communities. The interface between the legitimate medical use of opioids to provide analgesia and the phenomena associated with abuse and addiction continues to challenge the clinical community, leading to uncertainty about the appropriate role of these drugs in the treatment of pain. This narrative review briefly describes the neurobiology of opioids and then focuses on the complex issues at this interface between analgesia and abuse, including terminology, clinical challenges, and the potential for new agents, such as buprenorphine, to influence practice.

Post hoc analysis of a randomized, double-blind, placebo-controlled efficacy and tolerability study of tramadol extended release for the treatment of osteoarthritis pain in geriatric patients

BACKGROUND

Once-daily tramadol extended release (ER) was evaluated for 12 weeks in a randomized, double-blind, placebo-controlled, parallel-group study in 1020 patients with osteoarthritis of the knee or hip. As previously reported, compared with placebo, the results of the study showed that patients treated with tramadol ER had significant improvement in the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index and in pain-related sleep parameters.

OBJECTIVE

Because chronic/persistent arthritis pain is common in geriatric patients, this post hoc analysis evaluated the efficacy and tolerability of tramadol ER in geriatric patients 65 years or older (n=317) from this study.

METHODS

In the original study, the co-primary efficacy variables to evaluate the efficacy and tolerability of 100-, 200-, 300-, and 400-mg doses of tramadol ER were the WOMAC Osteoarthritis Index subscale scores for pain (0-500) and physical function (0-1700), and patient global assessment of disease (0-100). Secondary efficacy variables included arthritis pain intensity, 36-Item Short-Form Health Survey, daily pain diaries, sleep parameters, and tolerability assessments. Patients rated their arthritis pain utilizing a 100-mm visual analog scale (VAS) (0=no pain, 100=extreme pain). Sleep parameters were evaluated based on a 100-mm VAS (0=never, 100=always).

RESULTS

A total of 317 patients 65 years or older were included in the analysis (186 women, 131 men). Compared with placebo, this analysis found a significant improvement from baseline to the final visit in the co-primary efficacy variables of pain (least-squares [LS] mean [SE], 108.7 [16.9]; P<or=0.05) and physical function (LS mean [SE], 366.4 [57.7]; P<or=0.05) subscale scores of the WOMAC Osteoarthritis Index; the patient global assessment of disease activity (LS mean [SE], 27.9 [3.9]; P<or=0.01) for the tramadol ER 300-mg group; and for the pain-related sleep effects for less awakenings by pain in the morning (100-, 200-, and 300-mg groups; P<or=0.05), less awakenings by pain during the night (200- and 300-mg groups; P<or=0.035), significantly better overall sleep quality (200-mg group only; P=0.037), and less trouble falling asleep due to pain (200-mg group only; P=0.025). Commonly reported adverse events in patients 65 years or older treated with tramadol ER included constipation (27.5%), nausea (23.4%), dizziness (22.7%), and headache (15.6%).

CONCLUSIONS

This post hoc analysis suggests that the tramadol ER 300-mg dose was associated with statistically significant improvement in pain intensity and physical function, and for most of the pain-related sleep effects among these geriatric patients with moderate chronic/persistent pain.

Challenging the equipotency calculation for transdermal buprenorphine: four case studies

AIMS

Opioids produce analgesia via different pain pathways. The aim of these case studies was to address the issue of opioid rotation or switching, raising the important issue of conversion ratios between different compounds and routes of administration.

RESULTS

We present two cases of neuropathic pain and two cases of nociceptive pain with a significant neuropathic component, which were successfully treated with transdermal buprenorphine after the failure of other opioids.

CONCLUSION

In each case, effective pain relief was produced by a lower dose than the proposed equipotency ratio of 1:75 would indicate, suggesting that a ratio of 1:110 to 1:115 may be more appropriate.

The opioid renewal clinic: a primary care, managed approach to opioid therapy in chronic pain patients at risk for substance abuse

OBJECTIVE

To measure the impact of a structured opioid renewal program for chronic pain run by a nurse practitioner (NP) and clinical pharmacist in a primary care setting.

PATIENTS AND SETTING

Patients with chronic noncancer pain managed with opioid therapy in a primary care clinic staffed by 19 providers serving 50,000 patients at an urban academic Veterans hospital.

DESIGN

Naturalistic prospective outcome study.

INTERVENTION

Based on published opioid prescribing guidelines and focus groups with primary care providers (PCPs), a structured program, the Opioid Renewal Clinic (ORC), was designed to support PCPs managing patients with chronic noncancer pain requiring opioids. After training in the use of opioid treatment agreements (OTAs) and random urine drug testing (UDT), PCPs worked with a pharmacist-run prescription management clinic supported by an onsite pain NP who was backed by a multi-specialty Pain Team. After 2 years, the program was evaluated for its impact on PCP practice and satisfaction, patient adherence, and pharmacy cost.

RESULTS

A total of 335 patients were referred to the ORC. Of the 171 (51%) with documented aberrant behaviors, 77 (45%) adhered to the OTA and resolved their aberrant behaviors, 65 (38%) self-discharged, 22 (13%) were referred for addiction treatment, and seven (4%) with consistently negative UDT were weaned from opioids. The 164 (49%) who were referred for complexity including history of substance abuse or need for opioid rotation or titration, with no documented aberrant drug-related behaviors, continued to adhere to the OTA. Use of UDT and OTAs by PCPs increased. Significant pharmacy cost savings were demonstrated.

CONCLUSION

An NP/clinical pharmacist-run clinic, supported by a multi-specialty team, can successfully support a primary care practice in managing opioids in complex chronic pain patients.

Pharmacological strategies for the management of cancer pain in developing countries

Pain associated with cancer is often under treated especially in the developing countries where there are problems of poor economy, poor purchasing power of the citizens, absence of effective national health insurance schemes, poor manpower, fake adulterated and expired drugs, poor drug storage conditions; adverse temperature conditions combined with poor power supply which may affect drug efficacy. There is also poor understanding of the physiopharmacology of cancer pain management by health care providers. Assessment of the severity of the pain by location, oncological type, as well as psychosocial, emotional and environmental factors are necessary. The pain often occurs from malignancy, from procedures done to diagnose, stage and treat the malignancy, and from the toxicities of therapy used in treating the cancer. The first priority of treatment is to control pain rapidly and completely, as judged by the patient. The second priority is to prevent recurrence of pain. Analgesic drugs are given 'by the ladder,' 'by the clock' and 'by the appropriate route' using the analgesic ladder guideline proposed by the World Health Organization (WHO). The pharmacological aspects of various drugs used in the management of cancer pain are discussed.

Overview of oral modified-release opioid products for the management of chronic pain

OBJECTIVE

To evaluate pharmaceutical and pharmacotherapeutic differences in oral opioid modified-release products used in the management of chronic pain.

DATA SOURCES

Searches of MEDLINE (1966-May 2006) and an extensive review of peer reviewed journals were conducted using the key search terms opioid, morphine, hydromorphone, and oxycodone. Supplemental information was gathered through the American Pain Society, and limited but relevant information was obtained from manufacturers' labeling.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated. Information deemed relevant was included for this review if it introduced new or well supported concepts or clarified clinical practice issues.

DATA SYNTHESIS

The recognition and treatment of pain has become a major focus of healthcare professionals. The Joint Commission on Accreditation of Healthcare Organizations mandates compliance with recommended standards, outcome measures, and other initiatives. A general review of pain management and pharmacokinetic parameters are included.

CONCLUSIONS

Oral modified-release products have enabled patients to better maintain pain control due to convenient dosing intervals and sustained blood concentrations. The differences between available oral modified-release products are half-life, cost, and formulation (excipients and drug-release properties).

Validation of the PAC-SYM questionnaire for opioid-induced constipation in patients with chronic low back pain

BACKGROUND

The Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire is a 12-item self-report instrument divided into abdominal, rectal and stool domains.

AIMS

This study aimed to (1) evaluate the psychometric properties of PAC-SYM in assessing the symptoms and severity of opioid-induced constipation; (2) test for differences in opioid-induced constipation between Durogesic fentanyl transdermal reservoir (TDF) and oral sustained-release morphine (SRM) in patients with chronic low back pain (CLBP).

METHODS

In a 13-month, open-label, parallel-group study, 680 patients were randomised to receive either TDF (n=338) or SRM (n=342) for CLBP. Assessments were recorded at Visit 1 (baseline), Visit 5 (Day 29) and Visit 17 (Month 13). Concurrent validity, clinical validity and responsiveness of PAC-SYM were determined based on patients' confirmation of constipation (CC) scores. Differences in PAC-SYM scores between treatment groups were also evaluated.

RESULTS

The study included 677 patients, of whom 638 were opioid-naïve. Mean PAC-SYM scores for constipated patients were substantially higher than for non-constipated patients, demonstrating good clinical validity for PAC-SYM. The PAC-SYM could detect changes in bowel function over the treatment period, indicating responsiveness. Homogeneity of each symptom domain exceeded Cronbach's alpha coefficient of 0.70, suggesting good internal consistency and reliability. Changes in mean PAC-SYM scores from baseline to Visit 5 and Visit 17 were significantly lower for the TDF group than for the SRM group, indicating that the TDF group experienced less severe constipation.

CONCLUSION

PAC-SYM is a reliable, valid and responsive measure of the presence and severity of opioid-induced constipation symptoms.

Transdermal fentanyl in the management of children with chronic severe pain: results from an international study

BACKGROUND

The current study was conducted to assess the safety and tolerability of a transdermal fentanyl delivery system for the relief of chronic pain in a pediatric population, and also to validate titration recommendations and conversion to transdermal fentanyl from oral opioid therapy.

METHODS

This 15-day (with 3-month extension), single-arm, open-label trial was conducted at 66 sites in 10 countries. A total of 199 pediatric patients (ages 2-16 years) with both malignant and nonmalignant conditions who were receiving oral or parenteral opioids for moderate to severe chronic pain were enrolled. Transdermal fentanyl doses were titrated upward according to the rescue medication consumed during the previous application period. Degree of pain was assessed by patients and parents/guardians using visual and numeric scales. Level of play and quality of life were assessed using the Play Performance Scale (PPS) and the Child Health Questionnaire (CHQ). Adverse events were monitored on Days 1-15. Hypoventilation and sedation were monitored every 4 hours during the first 72 hours of the study.

RESULTS

A total of 173 patients completed the primary treatment period and 130 entered the extension phase. The average daily pain intensity scores were reported to have decreased by Day 16 and improvements in the mean PPS scores were observed to the end of the extension period. The CHQ scores demonstrated improvements in 11 of 12 domains after Month 1 of the extension period.

CONCLUSIONS

Transdermal fentanyl was found to be a safe and well tolerated alternative to oral opioid treatment for children ages 2-16 years who were previously exposed to opioid therapy.

Equipotent doses of transdermal fentanyl and transdermal buprenorphine in patients with cancer and noncancer pain: results of a retrospective cohort study

BACKGROUND

The equipotency ratio of transdermal (TD) fentanyl to oral morphine has been established as 1:100; for buprenorphine TD, a ratio of 1:75 has been proposed, although this ratio has not been confirmed in clinical studies. Growing evidence from clinical practice, in which much lower doses of buprenorphine are used, suggests that this conversion ratio may be too high.

OBJECTIVE

The aim of this study was to compare calculated equipotent oral morphine doses of fentanyl TD with equipotent oral morphine doses of buprenorphine TD prescribed in clinical practice.

METHODS

This retrospective study identified patients with cancer and noncancer pain who had received > or =1 prescription for fentanyl TD or buprenorphine TD (the all-patients groups) from the German IMS Disease Analyzer-mediplus database, which contains all relevant data concerning drug prescriptions from 400 practices in Germany. Also identified were subgroups of the all-patients groups who had received long-term treatment with fentanyl TD or buprenorphine TD and were considered to have similar pain intensity, as they had previously received similar analgesic medication (the identical-cohort groups). Mean prescribed daily doses for the all-patients and identical-cohort groups were calculated based on the distribution of prescribed patch strengths. Because patients could have applied >1 patch, mean prescribed daily doses were also calculated based on an assumption of double application when appropriate. Equipotent oral morphine doses were estimated using equipotency ratios of 1:100 for fentanyl TD and 1:75 for buprenorphine TD.

RESULTS

The all-patients groups consisted of 2198 patients with noncancer pain and 2544 patients with cancer pain; the identical-cohort groups consisted of 380 patients with noncancer pain and 496 patients with cancer pain (529 women, 347 men; mean age, 74 years [range, 25-101 years]). Equipotent doses of oral morphine were significantly lower in patients receiving buprenorphine TD compared with those receiving fentanyl TD (P < 0.001). In cancer patients, the equipotent oral morphine doses of fentanyl TD and buprenorphine TD were 130.9 to 138.9 mg and 85.2 to 88.8 mg, respectively; in noncancer patients, the corresponding values were 117.0 to 118.3 mg and 80.2 to 80.9 mg. Based on these results, an equipotency ratio of 1:110 to 1:115 for buprenorphine TD would appear to be more appropriate than the proposed ratio of 1:75.

CONCLUSIONS

The fact that this retrospective analysis conducted in identical cohorts showed lower calculated equipotent oral morphine doses in the buprenorphine TD groups compared with the fentanyl TD groups calls into question the proposed 1:75 ratio for conversion of buprenorphine TD to equipotent oral morphine doses. Based on the findings of the present study, an equipotency ratio of 1:110 to 1:115 may be more appropriate. However, confirmative data from prospective randomized clinical trials are needed.

Endogenous opiates and behavior: 2003

This paper is the 26th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2003 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Transdermal buprenorphine in the treatment of chronic pain: Resultsof a phase III, multicenter, randomized, double-blind, placebo-controlled study

BACKGROUND

Buprenorphine, a potent opioid analgesic, has been available in parenteral and oral or sublingual(SL) formulations for >25 years. In 2001, the buprenorphine transdermal delivery system (TES) was introduced at 3 release rates (35, 52.5, and 70 microg/h) for the treatment of chronic cancer and noncancer pain.

OBJECTIVE

This study compared the analgesic efficacy and tolerability of buprenorphine TES at a release rate of 35 microg/h with those of buprenorphine SL and placebo in patients with severe or very severe chronic cancer or noncancer pain.

METHODS

This multicenter, double-blind, placebo-controlled, parallel-group trial was 1 of 3 Phase III studies involved in the clinical development of buprenorphine TDS. It comprised a 6-day open-label run-in phase in which patients received buprenorphine SL 0.8 to 1.6 mg/d as needed and a double-blind phase in which patients were randomized to receive 3 sequential patches containing buprenorphine TES 35 microg/h or placebo, each lasting 72 hours. Rescue analgesia consisting of buprenorphine SL 02-mg tablets was available as needed throughout the double-blind phase. The main outcome measures were (1) the number of buprenorphine SL tablets required in addition to buprenorphine TES during the double-blind phase compared with the placebo group and compared with the buprenorphine SL requirement during the run-in phase, and (2) patients' assessments of pain intensity, pain relief, and duration of sleep uninterrupted by pain in the double-blind phase compared with the run-in phase. Adverse events were documented throughout the study.

RESULTS

One hundred thirty-seven patients were included in the double-blind phase (90 buprenorphine TES, 47 placebo). The buprenorphine TES group included 47 men and 43 women (mean [SD] age, 56.0 [12.1] years), and the placebo group included 23 men and 24 women (mean age, 55.7 [12.9] years). Forty-five patients had cancer-related pain and 92 had noncancer-related pain. The 2 treatment groups were comparable with respect to sex distribution, age, height, and body weight Patients receiving buprenorphine TES significantly reduced their consumption of buprenorphine SL tablets in the double-blind phase compared with patients receiving placebo (reduction of 0.6 [0.4] mg vs 0.4 [0.4] mg; P = 0.03). The relationship between the buprenorphine SL dose in the run-in phase and the number of buprenorphine SL tablets required in the double-blind phase was dose dependent in the active-treatment group only. Patients' assessments of pain intensity and pain relief suggested better analgesia with buprenorphine TES than with placebo, although the differences did not reach statistical significance. The proportion of patients who reported sleeping for >6 hours uninterrupted by pain in the double-blind phase compared with the run-in phase increased by 6.4% in the buprenorphine TDS group (35.6% vs 292%, respectively), compared with a decrease of 5.9% in the placebo group (40.4% vs 463%); no statistical analysis of sleep duration data was performed. Buprenorphine TDS was well tolerated, with adverse events generally similar to those associated with other opioids. The incidence of systemic adverse events in the double-blind phase was similar in the 2 treatment groups (28.9% buprenorphine TDS, 27.6% placebo), with the most common adverse events being nausea, dizziness, and vomiting. After patch removal, skin reactions (mainly mild or moderate pruritus and erythema) were seen in 35.6% of the buprenorphine TDS group and 25.5% of the placebo group.

CONCLUSIONS

In the population studied, buprenorphine TDS provided adequate pain relief, as well as improvements in pain intensity and duration of pain-free sleep. It may be considered a therapeutic option for the treatment of moderate to severe chronic pain.

Self-treatment of pain in a rural area

CONTEXT

In the United States, 42% of adults say they experience pain daily, the majority often relying on self-treatment. In addition, an increasing number of people are seeking complementary/alternative therapies, often without informing their health care providers.

PURPOSE

To explore the occurrence of pain and the modalities of self-treatment used by community members (N = 108) from a rural area of Michigan, the potential for interactions between pain self-treatment modalities and other medications currently being taken, and demographic variables that might affect self-treatment choice.

METHOD

This exploratory descriptive study was conducted using a survey method.

FINDINGS

Findings revealed that 66% were taking prescription medications, 75% over-the-counter medications, 20% herbal supplements, and 35% nonpharmacological treatments. Of the reported prescription and over-the-counter medications, 18% were opioids, 77% were nonopioids, and 18% were adjuvant medications. One-third of the subjects were taking more than 1 medication and/or herbal product or supplement, increasing their risk for potential drug-herb interactions, complicated by the fact that 20% did not inform their primary care practitioner of their self-treatment choices.

CONCLUSIONS

This study contributes to the knowledge of current self-treatment choices regarding pain management and potentially harmful interactions that might occur from using multiple medications and supplements.