Neuropathic pain responds better to increased doses of pregabalin: an in-depth analysis of flexible-dose clinical trials

Background

Pregabalin is an effective treatment option for many patients with neuropathic pain. Higher doses of pregabalin have been shown to be more effective in improving pain outcomes but, in practice, failing to appropriately increase the dose can leave patients under-treated.

Methods

This was a pooled analysis of 6 flexible-dose clinical trials of pregabalin in patients with neuropathic pain (diabetic peripheral neuropathy, peripheral herpetic neuralgia, posttraumatic pain, or postsurgical pain). Patients were divided into “dose pathway” groups based on their weekly pregabalin dose from the start of their trial to the first week of their maintenance phase. These were: 150 mg/day only; 150 to 300 mg/day; 150 to 300 to 450 mg/day; 150 to 300 to 450 to 600 mg/day; 150 to 300 to 600 mg/day; 300 to 600 mg/day. Pain outcomes assessed for each group at each new dose were proportion of 30% and 50% responders (≥30% or ≥50% reduction in mean pain score from baseline) and mean change in pain score. Percent change in mean pain score from baseline was assessed using a marginal structural model.

Results

Seven hundred and sixty-one patients treated with flexible-dose pregabalin were included in the analysis. For each dose pathway group, there was a notably greater proportion of 30% and 50% responders and change in pain score, at each escalating dose. As assessed by the marginal structural model, higher doses of pregabalin were estimated to result in a significantly greater change in mean pain score at each week. This dose response with flexible-dose pregabalin was consistent with that previously observed with fixed-dose pregabalin.

Conclusion

Many patients who do not respond to lower doses of pregabalin will respond with notable improvements in pain outcomes when the dose is escalated. These data should encourage physicians treating patients with neuropathic pain to escalate pregabalin to the dose that delivers optimal analgesia and tolerable side effects.

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.

A pharmacological treatment algorithm for localized neuropathic pain

Neuropathic pain is caused by a lesion or disease affecting the somatosensory system and is difficult to manage, often proving refractory to existing treatments. In more than half of cases, it is localized and affects a specific, clearly circumscribed area of the body (localized neuropathic pain, or LNP). A recently developed screening tool enables patients with probable neuropathic pain/LNP to be identified quickly and easily. In view of the conflicting current treatment recommendations, an advisory board of pain specialists met in June 2015 to develop a complementary treatment guidance algorithm, for use in the primary care setting and by non-pain specialists. The starting point of the algorithm is a diagnosis of LNP and there was consensus that first-line treatment should be a topical analgesic agent, because the benefit/risk ratios are far better than for systemic agents. Topical application offers site-specific delivery, a lower total systemic dose and avoidance of first-pass metabolism, reducing the risk of adverse events and drug/drug interactions. The 5% lidocaine medicated plaster has most evidence supporting its use in LNP, producing effective analgesia and reducing the associated area of allodynia, but other topical agents include capsaicin, clonidine and botulinum toxin type A. Treatment should be commenced with the topical agent of choice, and the patient re-assessed after an appropriate period. Where the response is good the topical agent is continued, with a re-evaluation after 3-6 months. A systemic agent (e.g. gabapentin, pregabalin, duloxetine, venlafaxine) is added if there is only a partial response, or substituted if there is no response, and the patient re-assessed after a month. If there is poor or no response to the systemic agent the patient should be switched to an alternative one and, if this also proves ineffective, referred to a pain specialist.

Diagnosis and management of postherpetic neuralgia

Risk factors for postherpetic neuralgia (PHN) include: increasing age; a prodrome of pain before rash onset; the degree of spread of the rash, particularly if it extends beyond a single dermatome; and severity of pain during the acute attack. Forty per cent of patients over 50 and 75% of those over 75 develop PHN following resolution of the rash. Patients develop persistent pain classified as PHN 120 days following rash onset. It can be either constant or paroxysmal and is commonly described as burning, stabbing or itching and located in the same dermatomal distribution as the shingles rash. Pain can lead to sleep disturbance, anorexia, reduced socialisation and reactive depression. Paracetamol should be tried initially for mild to moderate pain, either alone or in combination with codeine but there is no evidence to support the use of NSAIDs. Compared with other antidepressants, tricyclic antidepressants are the most likely to confer benefit in neuropathic pain. In frail elderly patients nortriptyline appears to be tolerated best. Both gabapentin and pregabalin can reduce pain and improve sleep patterns in patients with PHN. Patients with severe pain or those whose condition is affecting their daily activities and function should be referred to a specialist in pain management.

A comprehensive drug safety evaluation of pregabalin in peripheral neuropathic pain

Pregabalin is a commonly used therapy currently recommended as first-line treatment for a number of neuropathic pain (NeP) conditions. Since licensure, a number of clinical trials of pregabalin in different NeP conditions have been completed from which additional data on safety and tolerability can be drawn. In this analysis, patient-level data from 31 randomized clinical trials of pregabalin in peripheral NeP sponsored by Pfizer were pooled and assessed for incidence of adverse events (AEs). Incidence by age, disease condition, and race, together with risk differences and time to onset and resolution of AEs, was assessed. In total, 7,510 patients were included: 4,884 on pregabalin (representing 805 patient-years treatment) and 2,626 on placebo. Pregabalin vs. placebo risk analysis identified 9 AEs with a risk difference, for which the lower limit of the 95% confidence interval (CI) was > 1%: dizziness (risk difference [95% CI]: (17.0 [15.4 to 18.6]), somnolence (10.8 [9.5 to 12.1]), peripheral edema (5.4 [4.3 to 6.4]), weight increase (4.7 [3.9 to 5.5]), dry mouth (2.9 [2.1 to 3.8]), constipation (2.3 [1.5 to 3.2]), blurred vision (2.2 [1.6 to 2.9]), balance disorder (2.0 [1.5 to 2.5]), and euphoric mood (1.6 [1.2 to 2.0]). The most common AEs, dizziness and somnolence, typically emerged within the first 1 to 2 weeks of treatment and resolved 1 to 2 weeks later, without resulting in cessation of treatment. The data from this review provide information, indicating which AEs may be expected in patients treated with pregabalin, and suggest that careful dose titration to the highest tolerable dose is the most appropriate approach in clinical practice.

Relationships between changes in pain severity and other patient-reported outcomes: an analysis in patients with posttraumatic peripheral neuropathic pain

Background

The objective of this study is to use the pain numeric rating scale (NRS) to evaluate associations between change in pain severity and changes in sleep, function, and mood assessed via patient-reported outcomes (PROs) in patients with posttraumatic pain.

Methods

This is a secondary analysis of a clinical trial evaluating pregabalin in patients with posttraumatic peripheral neuropathic pain (N = 254). Regression models were used to determine associations between changes in pain (0-10 NRS) as the predictor and scores on the following PRO measures as the outcome: Pain Interference Index; Hospital Anxiety and Depression Scale anxiety and depression subscales; Medical Outcomes Study-Sleep Scale 9-item Sleep Problems Index and Sleep Disturbance subscale; and Daily Sleep Interference Scale (0-10 NRS).

Results

Change in pain severity showed clear, direct relationships with changes in function, anxiety, depression, and sleep PROs, all of which were statistically significant (P <.001). Results from subgroup analyses (≥30% or ≥50% pain responders, pregabalin or placebo treatment, age ≤ 51 years or > 51 years) tended to be consistent with results from the overall sample.

Conclusions

Overall, a direct relationship exists between pain and various aspects of patient's well-being and functioning, which can provide a quantitative assessment of how improvements in pain may be expected to relate to other patient outcomes. (http://ClinicalTrials.gov Identifier number NCT00292188; EudraCT #2005-003048-78).

An investigation of constructions of justice and injustice in chronic pain: A Q-methodology approach

This study used Q-methodology to explore justice-related accounts of chronic pain. Eighty participants completed the Q-sorting procedure (33 chronic pain sufferers and 47 non-pain sufferers). Analysis revealed five main factors. Three factors blame: society for poor medical and interpersonal treatment; the chronic pain sufferer for indulging in self-pity and unempathic healthcare workers for ignoring patients. A fourth factor acknowledges the unfairness of pain and encourages self-reliance. The fifth factor rejects injustice in the chronic pain discourse. Overall, there is a shared view that chronic pain brings unfair treatment, disrespect and a de-legitimization of pain. Future research ideas are suggested.

Pregabalin in the treatment of post-traumatic peripheral neuropathic pain: a randomized double-blind trial

BACKGROUND

Pregabalin is effective in the treatment of peripheral and central neuropathic pain. This study evaluated pregabalin in the treatment of post-traumatic peripheral neuropathic pain (including post-surgical).

METHODS

Patients with a pain score >or=4 (0-10 scale) were randomized and treated with either flexible-dose pregabalin 150-600 mg/day (n = 127) or placebo (n = 127) in an 8-week double-blind treatment period preceded by a 2-week placebo run-in.

RESULTS

Pregabalin was associated with a significantly greater improvement in the mean end-point pain score vs. placebo; mean treatment difference was -0.62 (95% CI -1.09 to -0.15) (P = 0.01). The average pregabalin dose at end-point was approximately 326 mg/day. Pregabalin was also associated with significant improvements from baseline in pain-related sleep interference, and the Medical Outcomes Study sleep scale sleep problems index and sleep disturbance subscale (all P < 0.001). In the all-patient group (ITT), pregabalin was associated with a statistically significant improvement in the Hospital Anxiety and Depression Scale anxiety subscale (P < 0.05). In total, 29% of patients had moderate/severe baseline anxiety; treatment with pregabalin in this subset did not significantly improve anxiety. More patients reported global improvement at end-point with pregabalin than with placebo (68% vs. 43%; overall P < 0.01). Adverse events led to discontinuation of 20% of patients from pregabalin and 7% from placebo. Mild or moderate dizziness and somnolence were the most common adverse events in the pregabalin group.

CONCLUSION

Flexible-dose pregabalin 150-600 mg/day was effective in relieving neuropathic pain, improving disturbed sleep, improving overall patient status, and was generally well tolerated in patients with post-traumatic peripheral neuropathic pain.

5% lidocaine medicated plaster versus pregabalin in post-herpetic neuralgia and diabetic polyneuropathy: an open-label, non-inferiority two-stage RCT study

OBJECTIVE

To compare efficacy and safety of 5% lidocaine medicated plaster with pregabalin in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

STUDY DESIGN AND METHODS

This was a two-stage adaptive, randomized, open-label, multicentre, non-inferiority study. Data are reported from the initial 4-week comparative phase, in which adults with PHN or painful DPN received either topical 5% lidocaine medicated plaster applied to the most painful skin area or twice-daily pregabalin capsules titrated to effect according to the Summary of Product Characteristics. The primary endpoint was response rate at 4 weeks, defined as reduction averaged over the last three days from baseline of > or = 2 points or an absolute value of < or = 4 points on the 11-point Numerical Rating Scale (NRS-3). Secondary endpoints included 30% and 50% reductions in NRS-3 scores; change in allodynia severity rating; quality of life (QoL) parameters EQ-5D, CGIC, and PGIC; patient satisfaction with treatment; and evaluation of safety (laboratory parameters, vital signs, physical examinations, adverse events [AEs], drug-related AEs [DRAEs], and withdrawal due to AEs).

RESULTS

Ninety-six patients with PHN and 204 with painful DPN were analysed (full analysis set, FAS). Overall, 66.4% of patients treated with the 5% lidocaine medicated plaster and 61.5% receiving pregabalin were considered responders (corresponding numbers for the per protocol set, PPS: 65.3% vs. 62.0%). In PHN more patients responded to 5% lidocaine medicated plaster treatment than to pregabalin (PPS: 62.2% vs. 46.5%), while response was comparable for patients with painful DPN (PPS: 66.7% vs 69.1%). 30% and 50% reductions in NRS-3 scores were greater with 5% lidocaine medicated plaster than with pregabalin. Both treatments reduced allodynia severity. 5% lidocaine medicated plaster showed greater improvements in QoL based on EQ-5D in both PHN and DPN. PGIC and CGIC scores indicated greater improvement for 5% lidocaine medicated plaster treated patients with PHN. Improvements were comparable between treatments in painful DPN. Fewer patients administering 5% lidocaine medicated plaster experienced AEs (safety set, SAF: 18.7% vs. 46.4%), DRAEs (5.8% vs. 41.2%) and related discontinuations compared to patients taking pregabalin.

CONCLUSION

5% lidocaine medicated plaster showed better efficacy compared with pregabalin in patients with PHN. Within DPN, efficacy was comparable for both treatments. 5% lidocaine medicated plaster showed a favourable efficacy/safety profile with greater improvements in patient satisfaction and QoL compared with pregabalin for both indications, supporting its first line position in the treatment of localized neuropathic pain.

Efficacy and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin in post-herpetic neuralgia and diabetic polyneuropathy

OBJECTIVE

Neuropathic pain is often difficult to treat due to a complex pathophysiology. This study evaluated the efficacy, tolerability and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin for neuropathic pain in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

METHODS

Patients completing 4-week monotherapy with 5% lidocaine medicated plaster or pregabalin were enrolled in an 8-week combination phase. Patients with adequate response to monotherapy (recalled average pain intensity of 4 or less on 11-point numeric rating scale in the previous 3 days [NRS-3 score]) continued their previous therapy, whereas those with insufficient response received combination therapy. Efficacy endpoints included change in NRS-3 from combination phase baseline, Patient and Clinical Global Impression of Change (PGIC/CGIC), and patient's satisfaction with treatment. Safety evaluation included adverse events (AEs), drug-related AEs (DRAEs), and withdrawal due to AEs.

CLINICAL TRIAL REGISTRATION

EudraCT No. 2006-003132-29.

RESULTS

Of 229 patients in the per-protocol set (PPS: 68 PHN and 161 DPN), 71 received 5% lidocaine medicated plaster monotherapy, 57 had pregabalin added to 5% lidocaine medicated plaster, 57 pregabalin monotherapy and 44 received 5% lidocaine medicated plaster in addition to continued pregabalin treatment. There were no meaningful differences in demographic data between the treatment groups. Patients continuing on monotherapy demonstrated additional decreases in NRS-3 scores. Patients receiving combination therapy achieved clinically relevant reduction in NRS-3 values in addition to improvement achieved during the 4 weeks of monotherapy. Improvement was similar between the two combination therapy groups. Considerable improvements in patients' treatment satisfaction were reported. Incidences of AEs were in line with previous reports for the two treatments and combination therapy was generally well tolerated.

CONCLUSIONS

In patients with PHN and painful DPN failing to respond to monotherapy, combination therapy with 5% lidocaine medicated plaster and pregabalin provides additional clinically relevant pain relief and is safe and well-tolerated.

Efficacy and safety of 5% lidocaine (lignocaine) medicated plaster in comparison with pregabalin in patients with postherpetic neuralgia and diabetic polyneuropathy: interim analysis from an open-label, two-stage adaptive, randomized, controlled trial

BACKGROUND AND OBJECTIVE

Postherpetic neuralgia (PHN) and diabetic polyneuropathy (DPN) are two common causes of peripheral neuropathic pain. Typical localized symptoms can include burning sensations or intermittent shooting or stabbing pains with or without allodynia. Evidence-based treatment guidelines recommend the 5% lidocaine (lignocaine) medicated plaster or pregabalin as first-line therapy for relief of peripheral neuropathic pain. This study aimed to compare 5% lidocaine medicated plaster treatment with pregabalin in patients with PHN and patients with DPN.

METHODS

The study was a two-stage, adaptive, randomized, controlled, open-label, multicentre trial that incorporated a drug wash-out phase of up to 2 weeks prior to the start of the comparative phase. At the end of the enrollment phase, patients who fulfilled the eligibility criteria were randomized to either 5% lidocaine medicated plaster or pregabalin treatment and entered the 4-week comparative phase. The interim analysis represents the first stage of the two-stage adaptive trial design and was planned to include data from the comparative phase for the first 150 randomized patients of the 300 total planned for the trial. Patients aged > or = 18 years with PHN or DPN were recruited from 53 investigational centres in 14 European countries. For this interim analysis, 55 patients with PHN and 91 with DPN (full-analysis set [FAS]), randomly assigned to the treatment groups, were available for analysis. Topical 5% lidocaine medicated plaster treatment was administered by patients to the area of most painful skin. A maximum of three or four plasters were applied for up to 12 hours within each 24-hour period in patients with PHN or DPN, respectively. Pregabalin capsules were administered orally, twice daily. The dose was titrated to effect: all patients received 150 mg/day in the first week and 300 mg/day in the second week of treatment. After 1 week at 300 mg/day, the dose of pregabalin was further increased to 600 mg/day in patients with high pain intensity scores. The pre-planned primary study endpoint was the rate of treatment responders, defined as completing patients experiencing a reduction from baseline of > or = 2 points or an absolute value of < or = 4 points on the 11-item numerical rating scale of recalled average pain intensity over the last 3 days (NRS-3), after 4 weeks of treatment. Secondary endpoints included > or = 30% and > or = 50% reductions in NRS-3 scores, changes in neuropathic pain symptom inventory (NPSI) scores and allodynia severity ratings. Overall, 65.3% of patients treated with the 5% lidocaine medicated plaster and 62.0% receiving pregabalin responded to treatment with respect to the primary endpoint. A higher proportion of PHN patients responded to plaster treatment compared with pregabalin (63.0% vs 37.5%), whereas in the larger DPN group treatments were comparable. Both treatments improved NPSI scores and reduced allodynia severity. Patients administering lidocaine plaster experienced fewer drug-related adverse events (3.9% vs 39.2%) and there were substantially fewer discontinuations due to drug-related adverse events (1.3% vs 20.3%).

CONCLUSION

After 4 weeks, 5% lidocaine medicated plaster treatment was associated with similar levels of analgesia in patients with PHN or DPN but substantially fewer frequent adverse events than pregabalin.

Laparoscopic colonic resection in fast-track patients does not enhance short-term recovery after elective surgery

BACKGROUND

Laparoscopic colorectal surgery has been claimed to enhance recovery when compared with open surgery. The aim of our study was to investigate whether laparoscopic colorectal resection improved recovery with the use of a multimodal rehabilitation programme.

METHOD

We carried out a prospective audit of 80 patients undergoing elective colorectal resection between November 2003 and March 2005. All patients underwent a fast-track protocol with early feeding, mobilization and a fluid and sodium restriction regime. Recovery was measured in terms of return of gastrointestinal function, hospital stay, complications and quality of life measures.

RESULTS

Of the 80 patients in the study 22 underwent laparoscopic resection and 58 had open surgery. Patients were well matched for all baseline characteristics. The groups were not significantly different in terms of opioid or antiemetic use. They were also similar in median time to first flatus (69 h vs 69 h, P = 0.36) and median time to first bowel motion (127 h vs 101 h, P = 0.07). There was no difference in median hospital stay (5.8 days vs 5.9 days, P = 0.87) or complications (P = 0.46) between the laparoscopic and open group. There were no significant differences in Short Form 36 scores between the two groups for any of the components measured.

CONCLUSION

Laparoscopic colorectal resection does not appear to reduce the duration of ileus or hospital stay with the use of a multimodal rehabilitation regime. Further large randomized trials are required to confirm these findings.

Intrathecal anesthesia with ketamine

BACKGROUND AND OBJECTIVES

Intrathecal anesthesia is the method of choice for transurethral prostate resection in the United Kingdom, despite its associated hypotension. Intrathecal ketamine with epinephrine has been used for lower limb surgery with minimal cardiovascular disturbance. Because cardiovascular stability might be advantageous in this group of elderly patients, we undertook this study to determine if intrathecal ketamine was a suitable intrathecal anesthetic agent for transurethral prostate surgery. Because of the high incidence of side effects and inadequate analgesia, the study was terminated after only ten patients had been recruited.

METHODS

Ten ASA I to III males were studied. Spinal anesthesia was performed with a 25-gauge Whitacre needle at the L2-L3 or L3-L4 space. The dose of ketamine was determined by a sequential allocation technique after initial empirical doses of 0.5 and 0.75 mg/kg. Sensory and motor block were monitored using pinprick and modified Bromage score, respectively. If spinal anesthesia was inadequate at any time, a general anesthetic was administered.

RESULTS

At doses higher than 0.7 mg/kg, intrathecal ketamine produced both motor and sensory block. The onset of motor block was within 2-3 minutes, peaked in 5-10 minutes, and lasted 30-60 minutes. Sensory block took 5-20 minutes to reach its maximal height. Maximum sensory block height varied from L1 to T7. Despite adequate block to pinprick, half the patients sensed the diathermy and were given a general anesthetic. The incidence of severe psychotomimetic side effects was 30%.

CONCLUSIONS

Intrathecal ketamine at doses of 0.7-0.95 mg/kg produces sensory and motor block. The frequency of psychomimetic disturbance, inadequate analgesia, and short duration of action preclude its use as a sole anesthetic agent.

Choosing the best needle for diagnostic lumbar puncture

A new generation of Atraumatic (blunt tipped) needles now exists in addition to the traditional Quincke (cutting tip) needles for LP. We wished to identify the optimal size and type of needle that should be used for this technique. Requirements include rapid and accurate transduction of CSF pressure and adequate flow rate for CSF collection purposes while minimizing headache and other neurologic sequelae. Different types of available Atraumatic and Quincke needles were tested in two models that simulated normal and raised CSF pressures. The flow rates and the time required for an accurate transduction of CSF pressure onto a standard spinal manometer through each needle type was measured. Overall, Atraumatic-tipped needles compared favorably with similarly sized Quincke needles tested. The 20-gauge needles displayed suitable flow and pressure transduction characteristics. Some of the 22-gauge Atraumatic needles rapidly measured CSF pressure, but their flow rates were only suitable for small volume CSF collection. There is extensive literature to support that neurologic sequelae are reduced using Atraumatic needles. Diagnostic LP can be easily and accurately performed by using a large Atraumatic needle with the potential for considerable reduction in post-LP headache and related neurologic sequelae.