Transdermal Buprenorphine for Central Neuropathic Pain: Clinical Reports

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Transdermal Buprenorphine for Acute Pain in the Clinical Setting: A Narrative Review

Transdermal buprenorphine is indicated for chronic pain management, but as its role in the clinical management of acute pain is less clear, this narrative review examines studies of the patch for acute pain, mainly in the postoperative setting. Although perhaps better known for its role in opioid rehabilitation programs, buprenorphine is also an effective analgesic that is a Schedule III controlled substance. Although buprenorphine is a partial agonist at the μ-opioid receptor, it is erroneous to think of the agent as a partial analgesic; it has full analgesic efficacy and unique attributes among opioids, such as a ceiling for respiratory depression and low “drug likeability” among those who take opioids for recreational purposes. Transdermal buprenorphine has been most thoroughly studied for acute pain control in postoperative patients. Postoperative pain follows a distinct and predictable trajectory depending on the type of surgery and patient characteristics. Overall, when the patch is applied prior to surgery and left in place for the prescribed seven days, it was associated with reduced postoperative pain, lower consumption of other analgesics, and patient satisfaction. Transdermal buprenorphine has been evaluated in clinical studies of patients undergoing gynecological surgery, hip fracture surgery, knee or hip arthroscopy/arthroplasty, shoulder surgery, and spinal surgery. Transdermal buprenorphine may also be appropriate pain medication for controlling pain during postsurgical orthopedic rehabilitation programs. Transdermal buprenorphine may result in typical opioid-associated side effects but with less frequency than other opioids. Despite clinical reservations about transdermal buprenorphine and its potential role in acute pain management in the clinical setting, clinical acceptance may be hampered by the fact that it is off-label and buprenorphine is better known as an opioid maintenance agent rather than an analgesic.

Pathophysiologic Approach to Pain Therapy for Complex Pain Entities: A Narrative Review

Pain management is challenging for both clinicians and patients. In fact, pain patients are frequently undertreated or even completely untreated. Optimal treatment is based on targeting the underlying mechanisms of pain and tailoring the management modality for each patient using a personalized approach. This narrative review deals with pain conditions that have a complex underlying mechanism and need an individualized and frequently multifactorial approach to pain management. The research is based on previously conducted studies, and does not contain any studies with human participants or animals performed by any of the authors. This is not an exhaustive review of the current evidence. However, it provides the clinician with a perspective on pain therapy targeting the underlying pain mechanism(s). When dealing with complex pain conditions, the prudent physician benefits from having a deep knowledge of various underlying pain mechanisms in order to provide a plan for optimal pharmacological pain relief to patients.

Satisfaction, Adherence and Health-Related Quality of Life with Transdermal Buprenorphine Compared with Oral Opioid Medications in the Usual Care of Osteoarthritis Pain

Background

Osteoarthritis (OA) causes substantial pain and reduced health-related quality of life (HRQL). Although opioid analgesics are commonly used, the relative benefits of different opioids are poorly studied. Transdermal buprenorphine (TDB) offers an alternative to oral opioids for the treatment of moderate-to-severe chronic pain. This observational study of people with OA pain assessed satisfaction, HRQL and medication adherence.

Methods

Patients in the UK with self-reported knee and/or hip OA who had been receiving one or more of TDB, co-codamol (an oral paracetamol/codeine combination) and tramadol for at least 1 month completed an online or telephone questionnaire. Medication satisfaction scores, HRQL scores (Short-Form 36 [SF-36]), medication adherence (Morisky Medication Adherence Scale [MMAS™]), adverse events and treatment discontinuations were recorded. Linear and logistic regression models were used to compare the treatment effect of TDB with co-codamol or tramadol.

Results

Overall, 966 patients met the inclusion criteria; 701 were taking only one of the target medications (TDB: 85; co-codamol: 373; tramadol: 243). The largest age group was 50–59 years and 76.0 % of patients were female. The TDB group was younger, with more male patients, therefore the statistical models were adjusted for age and sex. Medication satisfaction scores were significantly higher in the TDB group than the other two groups (TDB vs. co-codamol: 3.56, 95 % confidence interval [CI] 1.90–6.68, p < 0.0001; TDB vs. tramadol: 3.22, 95 % CI 1.67–6.20, p = 0.0005). Physical Component Summary scores for HRQL and mean adherence were also higher in the TDB group, while Mental Component Summary HRQL scores were similar across the three groups.

Conclusions

Patients with knee and/or hip OA pain treated with TDB were more satisfied and more adherent with their medication, and reported higher Physical Component Summary HRQL scores than those treated with co-codamol or tramadol, although demographic differences were observed between groups.

Electronic supplementary material

The online version of this article (doi:10.1007/s40271-016-0181-0) contains supplementary material, which is available to authorized users.

Assessment of Transdermal Buprenorphine Patches for the Treatment of Chronic Pain in a UK Observational Study

BACKGROUND

Opioids provide effective analgesia for moderate-to-severe, chronic pain. Transdermal buprenorphine (TDB) is available in the UK as weekly, lower-dose (5-20 μg/h) patches and twice-weekly, higher dose (35-70 μg/h) patches. This prospective, observational, multicenter study of patients with various chronic pain conditions assessed the safety, perceptions, and discontinuation of treatment with TDB in a real-world, non-interventional setting (ClinicalTrials.gov study ID: NCT01225861).

METHODS

Patients aged ≥18 years who were already receiving or initiating treatment with TDB were recruited in the UK during routine clinical visits and were followed for 6 visits or 9 months (whichever came first). Self-reported treatment adherence, patient satisfaction, and safety data were collected at each study visit.

RESULTS

Of 465 patients, 272 were already receiving 7-day TDB at the study start (TDB experienced), 146 were TDB naïve, and 47 were prescribed twice-weekly TDB. Most patients were female (72.9 %) and overweight/obese (body mass index ≥25: 75.3 %). The median age was 67 years, and the mean duration of pain was 11.1 years. Arthritis/other musculoskeletal disorders (39.6 %) were the most common causes of pain. Mild adverse events were commonly reported. Skin irritations, which were most frequent in 7-day TDB-experienced patients (45.6 %), rarely resulted in treatment discontinuation (8.8 %). Nearly all patients used TDB in accordance with treatment recommendations. Most patients reported that TDB was 'effective'/'very effective' at relieving pain and were 'satisfied'/'very satisfied' with TDB therapy.

CONCLUSION

In everyday clinical practice, TDB was well tolerated and patients were satisfied with their therapy. Self-reported adherence to TDB was very high, and adverse events rarely resulted in treatment discontinuation. Opportunities were identified to limit common adverse events associated with TDB.

Transdermal Buprenorphine Relieves Neuropathic Pain: A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Trial in Diabetic Peripheral Neuropathic Pain

OBJECTIVE

To evaluate the efficacy and safety of transdermal buprenorphine in patients with diabetic peripheral neuropathic pain (DPNP).

RESEARCH DESIGN AND METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group trial enrolled patients with type 1 or type 2 diabetes and stable glycemic control who had been experiencing moderate to severe DPNP for at least 6 months on maximal tolerated conventional therapy. Patients were randomly assigned to receive buprenorphine (5 μg/h) or placebo patches. The dose was titrated to effect to a maximum of 40 μg/h. Paracetamol was available as rescue analgesia. The severity of pain and other symptoms of DPNP were assessed daily in a patient diary and at clinic visits.

RESULTS

One hundred eight-six patients were enrolled, with 93 randomized to either buprenorphine or placebo. A high proportion of patients did not complete the study (buprenorphine 37 of 93, placebo 24 of 93). The main reason for premature withdrawal in the buprenorphine group was adverse events commonly due to untreated nausea and/or vomiting. Among the per-protocol population, more patients in the buprenorphine group (86.3%) experienced a 30% reduction in average versus baseline pain at week 12 than those in the placebo group (56.6%, P < 0.001). A nonsignificant trend favored the buprenorphine group within the intention-to-treat analysis of the same end point (51.7% vs. 41.3%, P = 0.175).

CONCLUSIONS

Transdermal buprenorphine, when tolerated, is an effective therapy for DPNP and provides another option to manage this challenging painful condition. Nausea and constipation need to be managed proactively to optimize treatment outcomes.

US practitioner prescribing practices and patient characteristics of those newly treated with a buprenorphine transdermal patch system

OBJECTIVES

Medication prescribing information provides guidance to healthcare providers on how to prescribe a drug properly. Oftentimes patient factors in addition to the prescribing information are considered when selecting medications. Utilizing real-world pharmacy and medical claims data, this study assessed US practitioner prescribing practices of US approved transdermal buprenorphine system (BTDS) in relation to BTDS's full prescribing information (FPI) as well as the relationship between patient factors and initial BTDS dose.

RESEARCH DESIGN AND METHODS

Patients aged ≥18 years initiating BTDS between 1 January 2011 and 30 November 2011 were identified in the IMS Pharmacy and Private Practitioner Medical Claims databases. The index date was defined as the first filled BTDS prescription. Demographics, chronic pain-related medical conditions in the 12 months pre-index and prior medication use in the 6 months pre-index were assessed. Initial BTDS dosing strength, receipt of approved initial BTDS dose per the FPI, and concomitant medications were assessed in the post-index 6 month period.

RESULTS

The study included 10,457 patients newly treated with BTDS. The majority of patients were female (69.9%) with a mean (±SD) age of 54.5 (±15.2) years. Within the 6 months prior to the index BTDS prescription, 91.7% of the patients used opioids. Overall, 48.9% of patients were prescribed the FPI approved BTDS dose. When stratified, 73.5% of opioid-naïve patients received the FPI approved initial dose compared to 46.0% of those with prior opioid experience of ≤80 mg morphine-equivalent daily dose. Patients on BTDS alone (i.e. monotherapy) had a higher rate of receiving the FPI approved initial BTDS dose compared to patients on BTDS concomitant regimens (p < 0.05).

CONCLUSIONS

Practitioners demonstrated that they prescribe in accordance with BTDS's prescribing information in the majority of opioid-naïve patients and in approximately half of opioid-experienced patients. The initial opioid dose is a critical step in treatment, setting the stage for preventing side-effects and improving treatment effectiveness. Understanding practitioner prescribing practices with regard to the initial dose selection of BTDS may provide insight on how to improve outcomes of care and reduce healthcare resource utilization and costs associated with pain management.

LIMITATIONS

Data obtained from prescription claims reflect only the activities of prescriptions filled, not medication use or other clinical characteristics observed by physicians when treating patients.

Parallel buprenorphine phMRI responses in conscious rodents and healthy human subjects

Pharmacological magnetic resonance imaging (phMRI) is one method by which a drug's pharmacodynamic effects in the brain can be assessed. Although phMRI has been frequently used in preclinical and clinical settings, the extent to which a phMRI signature for a compound translates between rodents and humans has not been systematically examined. In the current investigation, we aimed to build on recent clinical work in which the functional response to 0.1 and 0.2 mg/70 kg i.v. buprenorphine (partial µ-opioid receptor agonist) was measured in healthy humans. Here, we measured the phMRI response to 0.04 and 0.1 mg/kg i.v. buprenorphine in conscious, naive rats to establish the parallelism of the phMRI signature of buprenorphine across species. PhMRI of 0.04 and 0.1 mg/kg i.v. buprenorphine yielded dose-dependent activation in a brain network composed of the somatosensory cortex, cingulate, insula, striatum, thalamus, periaqueductal gray, and cerebellum. Similar dose-dependent phMRI activation was observed in the human phMRI studies. These observations indicate an overall preservation of pharmacodynamic responses to buprenorphine between conscious, naive rodents and healthy human subjects, particularly in brain regions implicated in pain and analgesia. This investigation further demonstrates the usefulness of phMRI as a translational tool in neuroscience research that can provide mechanistic insight and guide dose selection in drug development.

Modulation of CNS pain circuitry by intravenous and sublingual doses of buprenorphine

Buprenorphine (BUP) is a partial agonist at μ-, δ- and ORL1 (opioid receptor-like)/nociceptin receptors and antagonist at the κ-opioid receptor site. BUP is known to have both analgesic as well as antihyperalgesic effects via its central activity, and is used in the treatment of moderate to severe chronic pain conditions. Recently, it was shown that intravenous (IV) administration of 0.2mg/70 kg BUP modulates the blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) response to acute noxious stimuli in healthy human subjects. The present study extends these observations by investigating the effects of BUP dose and route of administration on central nervous system (CNS) pain circuitry. Specifically, the modulation of evoked pain BOLD responses and resting state functional connectivity was measured following IV (0.1 and 0.2mg/70 kg) and sublingual (SL) (2mg) BUP administration in healthy human subjects. While 0.1mg/70 kg IV BUP is sub-analgesic, both 0.2mg/70 kg IV BUP and 2.0mg SL BUP are analgesic doses of the drug. Evoked BOLD responses were clearly modulated in a dose-dependent manner. The analgesic doses of BUP by both routes of administration yielded a potentiation in limbic/mesolimbic circuitry and attenuation in sensorimotor/sensory-discriminative circuitry. In addition, robust decreases in functional connectivity between the putamen and the sensorimotor/sensory-discriminative structures were observed at the two analgesic doses subsequent to measuring the maximum plasma BUP concentrations (C(max)). The decreases in functional connectivity within the sensorimotor/sensory-discriminative circuitry were also observed to be dose-dependent in the IV administration cohorts. These reproducible and consistent functional CNS measures at clinically effective doses of BUP demonstrate the potential of evoked pain fMRI and resting-state functional connectivity as objective tools that can inform the process of dose selection. Such methods may be useful during early clinical phase evaluation of potential analgesics in drug development.