Low doses of amitriptyline, pregabalin, and gabapentin are preferred for management of neuropathic pain in India: is there a need for revisiting dosing recommendations?

Neuropathic pain management: a focused review of current treatments and novel data from main ongoing clinical trials

INTRODUCTION

Neuropathic pain (NP) remains a significant challenge in clinical practice, requiring a sophisticated pharmacotherapeutic strategy for effective symptom management. This review provides a comprehensive analysis of the current pharmacological treatments for NP, focusing on their efficacy, mechanism of action, and therapeutic potential. Additionally, it evaluates ongoing clinical trials investigating novel drugs and therapeutic approaches, highlighting emerging trends and future directions in NP management.

AREAS COVERED

This review examines first- to third-line therapeutic modalities for NP, critically analyzing their efficacy, safety profiles, and clinical applications. It also includes an overview of ongoing clinical trials exploring innovative pharmacological therapies. A thorough literature review was conducted using the MEDLINE database without temporal limitations, offering a detailed assessment of established and emerging treatments.

EXPERT OPINION

While current pharmacological options offer significant symptom relief, their overall effectiveness in managing NP remains limited, highlighting the need for further therapeutic advancements. Staying informed about emerging therapies and clinical trials is vital to enhancing patient care and quality of life. The future of NP management lies in optimizing individualized treatment strategies, refining therapeutic approaches, and fostering interdisciplinary collaboration. Close monitoring of outcomes and continued research are essential for advancing understanding and improving the precision of NP therapies.

Patterns of analgesic utilisation among people with knee osteoarthritis: a cohort study using UK primary care data

Background

Osteoarthritis (OA) is a prevalent disabling joint disease affecting more than 300 million people globally and knees are most commonly affected. It is associated with pain and functional limitation that adversely affect mental well-being and compromise quality of life. Analgesic use is common among patients with knee osteoarthritis (KOA), however, data on patterns of analgesics use at an individual patient level are sparse. The present study describes patterns of analgesic use, by determining the proportion of persistent users within one year of therapy initiation in patients with KOA.

Methods

A retrospective cohort study using the clinical practice research datalink. Analgesic prescriptions for adults with an incident KOA diagnosis were captured and grouped into five exposure groups including: antidepressants, antiepileptic drugs (AEDs), opioids, non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol. A persistent user was a person who used >180 defined daily doses (DDDs) per year and had prescriptions in at least three out of the four quarters of the year.

Results

Variable proportions of patients used respective analgesic classes persistently during the first year after prescribing; 36.8% of antidepressant users, 27.0% of NSAIDs, 23.8% of AEDs, 17.5% of paracetamol and 14.9% of opioid users were persistent users. Across classes, persistent users were slightly younger, were issued more prescriptions and used higher doses of analgesics compared to non-persistent users.

Conclusion

Between 14.9% and 36.8% became persistent analgesic users by the end of the first year after their initial prescription. The study applied meaningful clinical attributes to define persistence. This informs future research on clinical and adverse drug outcomes in persistent users compared to non-persistent users across five separate analgesic classes.

Drug Usability Survey (DUS) of Gabapentinoid and Its Combinations Among Indian Patients With Neuropathic Pain: Results From a Real-World, Multicenter, Retrospective Survey at Neurology Clinics

INTRODUCTION

 Neuropathic pain of various etiology is the most commonly reported at primary clinics by patients. Patients experience moderate to severe chronic pain, impacting quality of life (QoL) and mood. The mainstay of the treatment includes gabapentinoid-based treatment to reduce pain severity and improve the QoL for the patients.

METHODS

 In a retrospective cross-sectional survey in India, the drug usability of gabapentinoid-based treatment in various neuropathic pain was studied. This included data collection from various neurological clinics across India that considered patient demographics, comorbidities, type of neuropathies, the percentage of patients receiving gabapentinoid-based treatment, the share of diabetic patients and diabetic neuropathy, and the severity of pain reported by patients.

RESULTS

 The cross-sectional survey was conducted at 51 neurology clinics involving 2,251 patients. Patients presented with neuropathic pain of various etiologies, of which diabetic neuropathy was the most prevalent condition. Among the patients, 59.30% (1,252) consulted the neurologist for the first time, whereas 40.70% (860) of patients visited the clinic for follow-up. Neurologists prescribed gabapentinoid-based combination treatment as the main preferred treatment. Duloxetine, a selective serotonin and norepinephrine reuptake inhibitor (SSNRI) antidepressant, and nortriptyline, a tricyclic antidepressant (TCA), were the most preferred agents used in combination with pregabalin and gabapentin. Patients who visited for follow-up reported pain reduction and improved QoL with the treatment provided by the neurologists.

CONCLUSION

Gabapentinoid-based treatments combined with TCA and SSNRI are useful and well-accepted treatment modalities by neurologists in painful neuropathies. Gabapentinoids are non-opioids with no risk of abuse and addiction and were considered the first line of therapy for various types of neuropathic pain.

Efficacy of pregabalin, amitriptyline, and gabapentin for neuropathic pain

Neuropathic pain largely influences the well-being of patients. Anticonvulsant and antidepressant medications, such as Pregabalin, Gabapentin, and Amitriptyline, are routinely prescribed as initial treatments for neuropathic pain. The study sample has a total of 270 patients who meet the inclusion criteria and are further distributed into three equally sized groups (A, B, and C). Group A was administered with Gabapentine 300mg, Group B with Pregabalin 75 mg, and Amitriptyline 10 mg to Group C. The occurrence of any adverse drug response was documented using the ADR reporting form, while the pain of the patient's post-medication was recorded using a numerical pain rating scale (NPRS). The comparison of the NPRS scores of all three groups "by using ANOVA test" both at baseline and after 15 days reveal that the differences between the three groups are statistically insignificant (p > 0.089). However, after one month of continuous use, the difference becomes slightly significant (I.e., p = 0.003). Gabapentin, pregabalin, and amitriptyline demonstrate similar effectiveness in alleviating neuropathic (NeP) pain. The study concludes that gabapentin is superior to both pregabalin and amitriptyline with fewer adverse effects, leading to improved patient adherence for long-term use.

Acupuncture in diabetic peripheral neuropathy-neurological outcomes of the randomized acupuncture in diabetic peripheral neuropathy trial

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus and can lead to serious complications. Therapeutic strategies for pain control are available but there are few approaches that influence neurological deficits such as numbness.

AIM

To investigate the effectiveness of acupuncture on improving neurological deficits in patients suffering from type 2 DPN.

METHODS

The acupuncture in DPN (ACUDPN) study was a two-armed, randomized, controlled, parallel group, open, multicenter clinical trial. Patients were randomized in a 1:1 ratio into two groups: The acupuncture group received 12 acupuncture treatments over 8 wk, and the control group was on a waiting list during the first 16 wk, before it received the same treatment as the other group. Both groups received routine care. Outcome parameters were evaluated after 8, 16 and 24 wk and included neurological scores, such as an 11-point numeric rating scale (NRS) 11 for hypesthesia, neuropathic pain symptom inventory (NPSI), neuropathy deficit score (NDS), neuropathy symptom score (NSS); nerve conduction studies (NCS) were assessed with a handheld point-of-care device.

RESULTS

Sixty-two participants were included. The NRS for numbness showed a difference of 2.3 (P < 0.001) in favor of the acupuncture group, the effect persisted until week 16 with a difference of 2.2 (P < 0.001) between groups and 1.8 points at week 24 compared to baseline. The NPSI was improved in the acupuncture group by 12.6 points (P < 0.001) at week 8, the NSS score at week 8 with a difference of 1.3 (P < 0.001); the NDS and the TNSc score improved for the acupuncture group in week 8, with a difference of 2.0 points (P < 0.001) compared to the control group. Effects were persistent in week 16 with a difference of 1.8 points (P < 0.05). The NCS showed no meaningful changes. In both groups only minor side effects were reported.

CONCLUSION

Study results suggest that acupuncture may be beneficial in type 2 diabetic DPN and seems to lead to a reduction in neurological deficits. No serious adverse events were recorded and the adherence to treatment was high. Confirmatory randomized sham-controlled clinical studies with adequate patient numbers are needed to confirm the results.

Risk of cardiovascular events according to the tricyclic antidepressant dosage in patients with chronic pain: a retrospective cohort study

PURPOSE

We aimed to examine the risk of cardiovascular adverse events by tricyclic antidepressant (TCA) dosage among patients with chronic pain.

METHODS

A retrospective cohort study was conducted using a nationwide sample cohort. Among patients aged ≥ 18 years with a chronic pain diagnosis and no history of cardiovascular events, we extracted users and non-users of TCAs through 1:1 propensity score matching. TCA users were categorized into three groups according to the mean defined daily dose (DDD): very low doses (< 0.15 DDD), low doses (0.15-0.34 DDD), and traditional doses (≥ 0.34 DDD). A 6-month follow-up was conducted with an intention-to-treat approach. We examined the hazard ratio of cardiovascular adverse events using Cox proportional hazards analysis.

RESULTS

In total, 16,660 matched patients were followed up (8330 TCA users and 8330 non-users). TCA use did not significantly increase cardiovascular adverse events (hazard ratio [HR] 1.12, 95% confidence interval [CI] 0.94-1.33). Low-dose (0.15-0.34 DDD) TCAs (HR 1.37, 95% CI 1.08-1.74), particularly low-dose (0.15-0.34 DDD) nortriptyline (HR 2.11, 95% CI 1.44-3.08), was associated with an increased risk of cardiovascular adverse events. Administration of TCAs at the traditional dose (≥ 0.34 DDD) increased the risk of ischemic stroke (HR 2.08, 95% CI 1.11-3.88).

CONCLUSION

Close monitoring of patients on long-term, low-dose use of TCAs should be conducted to avoid an increase in the cumulative dose, which increases the risk of cardiovascular adverse events.

Early Optimized Pharmacological Treatment in Patients With Depression and Chronic Pain

Major depressive disorder (MDD) is the leading cause of disability worldwide. Patients with MDD have high rates of comorbidity with mental and physical conditions, one of which is chronic pain. Chronic pain conditions themselves are also associated with significant disability, and the large number of patients with MDD who have chronic pain drives high levels of disability and compounds healthcare burden. The management of depression in patients who also have chronic pain can be particularly challenging due to underlying mechanisms that are common to both conditions, and because many patients with these conditions are already taking multiple medications. For these reasons, healthcare providers may be reluctant to treat such patients. The Canadian Network for Mood and Anxiety Treatments (CANMAT) guidelines provide evidence-based recommendations for the management of MDD and comorbid psychiatric and medical conditions such as anxiety, substance use disorder, and cardiovascular disease; however, comorbid chronic pain is not addressed. In this article, we provide an overview of the pathophysiological and clinical overlap between depression and chronic pain and review evidence-based pharmacological recommendations in current treatment guidelines for MDD and for chronic pain. Based on clinical experience with MDD patients with comorbid pain, we recommend rapidly and aggressively treating depression according to CANMAT treatment guidelines, using antidepressant medications with analgesic properties, while addressing pain with first-line pharmacotherapy as treatment for depression is optimized. We review options for treating pain symptoms that remain after response to antidepressant treatment is achieved.

Clinical Remission Using Personalized Low-Dose Intravenous Infusions of N-acetylcysteine with Minimal Toxicities for Interstitial Cystitis/Bladder Pain Syndrome

Interstitial Cystitis or Bladder Pain Syndrome (IC/BPS) is a heterogeneous condition characterized by elevated levels of inflammatory cytokines, IL-1β, IL-6, IL-8, IL-10, TNF-α, and is associated with debilitating symptoms of pelvic pain and frequent urination. A standard of care for IC/BPS has not been established, and most patients must undergo a series of different treatment options, with potential for severe adverse events. Here, we report a patient with a 26-year history of IC/BPS following treatment with multiple therapies, including low doses of etodolac, amitriptyline and gabapentin, which she was unable to tolerate because of adverse effects, including headaches, blurred vision and cognitive impairment. The patient achieved a complete clinical remission with minimal adverse events after 16 cycles of N-acetylcysteine (NAC) intravenous (IV) infusions over a period of 5 months, and pro-inflammatory cytokine levels were reduced when compared to measurements taken at presentation. Personalized low dose NAC IV infusion therapy represents an effective, safe, anti-inflammatory therapy administered in the outpatient setting for IC/BPS, and warrants further investigation.

Pregabalin for neuropathic pain in primary care settings: recommendations for dosing and titration

Pregabalin is one of the first-line treatments approved for the management of neuropathic pain (NeP). While many patients benefit from treatment with pregabalin, they are often treated with suboptimal doses, possibly due to unfamiliarity around prescribing the drug and/or side effects that can occur with up-titration. This narrative review discusses key aspects of initiating, titrating, and managing patients prescribed pregabalin therapy, and addresses concerns around driving and the potential for abuse, as well as when to seek specialist opinion. To ensure that patients derive maximum therapeutic benefit from the drug, we suggest a 'low and slow' dosing approach to limit common side effects and optimize tolerability alongside patients' expectations. When requiring titration to higher doses, we recommend initiating 'asymmetric dosing,' with the larger dose in the evening. Fully engaging patients in order for them to understand the expected timeline for efficacy and side effects (including their resolution), can also help determine the optimal titration tempo for each individual patient. The 'low and slow' approach also recognizes that patients with NeP are heterogeneous in terms of their optimal therapeutic dose of pregabalin. Hence, it is recommended that general practitioners closely monitor patients and up-titrate according to pain relief and side effects to limit suboptimal dosing or premature discontinuation.

Prescription Pattern of Drugs Used for Neuropathic Pain and Adherence to NeuPSIG Guidelines in Cancer

Objective

The objective of the present research was to evaluate the prescription pattern of the drugs used in the pharmacological treatment of cancer-related neuropathic pain (CRNP) and to assess the adherence of the physicians to the Neuropathic Pain Special Interest Group (NeuPSIG) Guidelines.

Materials and Methods

This was a cross-sectional, observational study where patients who presented to the pain and palliative care outpatient clinic of the tertiary care hospital with CRNP were prospectively recruited. Participants were screened for neuropathic pain using DN4 questionnaire. Demographic details, diagnosis, medication details, and adherence to NeuPSIG guidelines were assessed using a validated questionnaire.

Results

Of 300 patients screened, 64% were male and 36% were female, with a mean age of 48.26 ± 13.05 years. The predominant symptoms found were pin-and-needle sensation (99%) followed by tingling sensation (98.66%). The most common diagnosis was head-and-neck cancers (37.3%) followed by bone cancers (17.3%) and lung cancers (15.3%). Among the first-line drugs recommended in NeuPSIG for CRNP, pregabalin (78.7%) was the most common drug prescribed followed by amitriptyline (67%). The most common co-prescribed drugs were acid suppressants drugs (50.7%). Tapentadol, which is not part of the NeuPSIG guidelines, was prescribed on 51 occasions for neuropathic pain. Underdosing was observed in 272 prescriptions. Only 12 prescriptions completely adhered, while 275 had partial, and 13 prescriptions had poor adherence to NeuPSIG guidelines.

Conclusion

The most commonly used drugs in the treatment of CRNP were pregabalin and amitriptyline. Most physician partially or did not adhere to the NeuPSIG guideline in the management of CRNP.

Pregabalin and gabapentin in neuropathic pain management after spinal cord injury: a systematic review and meta-analysis

Neuropathic pain after spinal cord injury (SCI) has a significant negative impact on the patients’ quality of life. The objective of this systematic review is to examine the safety and efficacy of pregabalin (PGB) and gabapentin (GBP) in the treatment of neuropathic pain due to SCI. PubMed, the Cochrane Library, Embase, Scopus, and the Web of Science were searched up to December 2018. The reference lists of key and review studies were reviewed for additional citations. The quality of the studies was evaluated using the Cochrane Collaboration’s tools for assessing the risk of bias. A meta-analysis was performed for primary and secondary outcomes. Eight studies were eligible for inclusion. Meta-analysis of PGB vs. placebo showed that PGB was effective for neuropathic pain (standardized mean difference [SMD] = −0.40; 95% confidence interval [CI]: −0.78, −0.01), anxiety (MD = −0.68; 95% CI: −0.77, −0.59), depression (mean difference [MD] = −0.99; 95% CI: −1.08, −0.89), and sleep interference (MD = −1.08; 95% CI: −1.13, −1.02). Also, GBP was more effective than a placebo for reducing pain. No significant difference was observed between the efficacy of the two drugs (MD = −0.37; 95% CI: −1.67, 0.93). There was no significant difference between the two drugs for discontinuation due to adverse events (risk ratio = 3.00; 95% CI: 0.81, 11.15). PGB and GBP were effective vs. placebos in decreasing neuropathic pain after SCI. Also, there was no significant difference between the two drugs for decreasing pain and adverse events.

Dual action of amitriptyline on NMDA receptors: enhancement of Ca-dependent desensitization and trapping channel block

Although the tricyclic antidepressant amitriptyline (ATL) is widely used in the clinic, the mechanism underlying its high therapeutic efficacy against neuropathic pain remains unclear. NMDA receptors (NMDARs) represent a target for ATL and are involved in sensitization of neuropathic pain. Here we describe two actions of ATL on NMDARs: 1) enhancement of Ca²⁺-dependent desensitization and 2) trapping channel block. Inhibition of NMDARs by ATL was found to be dependent upon external Ca²⁺ concentration ([Ca²⁺]) in a voltage-independent manner, with an IC₅₀ of 0.72 μM in 4 mM [Ca²⁺]. The ATL IC₅₀ value increased exponentially with decreasing [Ca²⁺], with an e-fold change observed per 0.69 mM decrease in [Ca²⁺]. Loading neurons with BAPTA abolished Ca²⁺-dependent inhibition, suggesting that Ca²⁺ affects NMDARs from the cytosol. Since there is one known Ca²⁺-dependent process in gating of NMDARs, we conclude that ATL most likely promotes Ca²⁺-dependent desensitization. We also found ATL to be a trapping open-channel blocker of NMDARs with an IC₅₀ of 220 µM at 0 mV. An e-fold change in ATL IC₅₀ was observed to occur with a voltage shift of 50 mV in 0.25 mM [Ca²⁺]. Thus, we disclose here a robust dependence of ATL potency on extracellular [Ca²⁺], and demonstrate that ATL bound in the NMDAR pore can be trapped by closure of the channel.

An Evaluation of Efficacy and Safety of Commonly Prescribed Drugs and Effect of These Drugs on Quality of Sleep in Patients Suffering From Zoster-Associated Pain

This observational, prospective, single-center study was conducted to evaluate the efficacy and safety of commonly prescribed drugs for zoster-associated pain and their impact on quality of sleep at a tertiary care hospital in western India. Patients ≥18 years of age, newly diagnosed with zoster-associated pain were evaluated on days 0, 7, 14, 30, 60, 90, 120, 150, and 180 or until resolution of pain, whichever was earlier, using the Wong Baker FACES Pain Rating Scale, Neuropathic Pain Scale, and Insomnia Severity Index for intensity of pain, quality of pain, and quality of sleep, respectively. A total of 78 patients (46.0 [16.3] years) completed the study. They received nonsteroidal anti-inflammatory drugs (65), gabapentin (30), amitriptyline (27), and amitriptyline + gabapentin (21) for mean durations of 7.7 (3.0), 89.2 (7.2), 107.6 (46.3), and 104.5 (46) days, respectively. Improvement in the Wong Baker FACES Pain Rating Scale and Neuropathic Pain Scale score was similar among treatment groups except for a greater fall in Wong Baker FACES Pain Rating Scale score at days 7 and 120 and that in deep pain score at day 7 in combination treatment group vs the amitriptyline group. Clinically significant insomnia was detected in 35 patients at baseline and demonstrated progressive and similar improvement among groups. Treatment modification was required in 20 patients. Zoster-associated pain resolved in 69 patients. Nine adverse drug reactions, mostly mild, nonserious, and nonpreventable, were reported. To conclude, drugs commonly used for zoster-associated pain are effective and well tolerated. These have a similar effect on pain and quality of sleep, except for a possible greater effect of combination treatment in the early phase of intense and deep pain.