A review on the efficacy and safety of gabapentin in the treatment of chronic cough

Practical multidisciplinary framework for the assessment and management of patients with unexplained chronic aerodigestive symptoms

OBJECTIVE

Patients experiencing unexplained chronic throat symptoms (UCTS) are frequently referred to gastroenterology and otolaryngology outpatient departments for investigation. Often despite extensive investigations, an identifiable structural abnormality to account for the symptoms is not found. The objective of this article is to provide a concise appraisal of the evidence-base for current approaches to the assessment and management of UCTS, their clinical outcomes, and related healthcare utilisation.

DESIGN

This multidisciplinary review critically examines the current understanding of aetiological theories and pathophysiological drivers in UCTS and summarises the evidence base underpinning various diagnostic and management approaches.

RESULTS

The evidence gathered from the review suggests that single-specialty approaches to UCTS inadequately capture the substantial heterogeneity and pervasive overlaps among clinical features and biopsychosocial factors and suggests a more unified approach is needed.

CONCLUSION

Drawing on contemporary insights from the gastrointestinal literature for disorders of gut-brain interaction, this article proposes a refreshed interdisciplinary approach characterised by a positive diagnosis framework and patient-centred therapeutic model. The overarching aim of this approach is to improve patient outcomes and foster collaborative research efforts.

Gabapentin alleviated the cough hypersensitivity and neurogenic inflammation in a guinea pig model with repeated intra-esophageal acid perfusion

OBJECTIVE

The anti-tussive effect of gabapentin and its underlying neuromodulatory mechanism were investigated via a modified guinea pig model of gastroesophageal reflux-related cough (GERC).

METHODS

Intra-esophageal perfusion with hydrochloric acid (HCl) was performed every other day 12 times to establish the GERC model. High-dose gabapentin (48 mg/kg), low-dose gabapentin (8 mg/kg), or saline was orally administered for 2 weeks after modeling. Cough sensitivity, airway inflammation, lung and esophagus histology, levels of substance P (SP), and neurokinin-1 (NK1)-receptors were monitored.

RESULTS

Repeated intra-esophageal acid perfusion aggravated the cough sensitivity in guinea pigs in a time-dependent manner. The number of cough events was significantly increased after 12 times HCl perfusion, and the hypersensitivity period was maintained for 2 weeks. The SP levels in BALF, trachea, lung, distal esophagus, and vagal ganglia were increased in guinea pigs receiving HCl perfusion. The intensity of cough hypersensitivity in the GERC model was significantly correlated with increased SP expression in the airways. Both high and low doses of gabapentin administration could reduce cough hypersensitivity exposed to HCl perfusion, attenuate airway inflammatory damage, and inhibit neurogenic inflammation by reducing SP expression from the airway and vagal ganglia.

CONCLUSIONS

Gabapentin can desensitize the cough sensitivity in the GERC model of guinea pig. The anti-tussive effect is associated with the alleviated peripheral neurogenic inflammation as reflected in the decreased level of SP.

Potential applications of P2X3 receptor antagonists in the treatment of refractory cough

Refractory chronic cough is defined as a clinical condition in which the cause of the cough remains unclear after comprehensive examination and treatment, or the cause is clear but symptomatic treatment is ineffective. Patients with refractory chronic cough experience a variety of physiological and psychological issues that significantly lower their quality of life and place a significant socio-economic burden on society. As a result, research both domestically and internationally has turned heavily toward these patients. Recently, several studies have identified P2X3 receptor antagonists for the treatment of refractory chronic cough, and this paper reviews the background, mechanism of action, evidence-based proof and application prospects of this class of drugs. KEY MESSAGE: There were plenty of studies about P2X3 receptor antagonists in the past, and in recent years this series of drugs are effective in refractory chronic cough. Although review articles summarizing have been published previously, most have focused on their chemical properties rather than their clinical aspects, with some omitting drugs that have been in clinical studies for nearly two years such as Eliapixant and Sivopixant. Focusing on four P2X3 receptor antagonists with proven efficacy in clinical studies, we analyzed the characteristics and disadvantages of each drug by comparing their clinical results of them and theoretically explained the common side effects of these drugs, as well as their potential for treating refractory chronic cough. This article can be used as a reference for the follow-up studies of P2X3 receptor antagonists in chronic cough. Additionally, it also has implications for the clinical focus of the drug and the approaches to relieve some side effects.

Gabapentin for chronic refractory cough: A system review and meta-analysis

Objective

To evaluate the efficacy and safety of gabapentin in the treatment of chronic refractory cough by Meta-Analysis.

Methods

Literatures were retrieved from PubMed, Embase (OvidIP), Cochrane Library, CNKI, VIP, Wanfang Database and China Biomedical Management System and eligible prospective studies were screened. Data were extracted and analyzed by using RevMan 5.4.1 software.

Results

Six articles (2 RCTs and 4 prospective studies) with 536 participants were finally included. Meta-analysis showed that gabapentin was better than placebo in cough-specific quality of life (LCQ score, MD = 4.02, 95%CI [3.26,4,78], Z = 10.34, P < 0.00001), cough severity (VAS score, MD = -29.36, 95% CI (-39.46, -19.26), Z = 5.7, P < 0.00001), cough frequency (MD = -29.87, 95% CI [- 43.84, -15.91], Z = 4.19, P < 0.0001) and therapeutic efficacy (RR = 1.37,95%CI [1.13,1.65], Z = 3.27, P = 0.001), and equal in safety (RR = 1.32,95%CI [0.47,3.7], Z = 0.53, P = 0.59). Gabapentin was similar to other neuromodulators in therapeutic efficacy (RR = 1.07,95%CI [0.87,1.32], Z = 0.64, P = 0.52), but its safety was better.

Conclusion

Gabapentin is effective in the treatment of chronic refractory cough in both subjective and objective evaluations, and its safety is better than other neuromodulators.

Prediction of therapeutic efficacy of gabapentin by Hull Airway Reflux Questionnaire in chronic refractory cough

Background:

Gabapentin is recommended for the treatment of chronic refractory cough (CRC). This study aims to identify its therapeutic predictors in a prospective clinical study.

Methods:

A total of 179 patients with CRC were treated with gabapentin. Prior to the therapy, all patients were assessed by Hull Airway Reflux Questionnaire (HARQ) and inhaled capsaicin challenge. When the treatment ended and cough resolution was confirmed, a stepwise logistic regression analysis was performed to identify the therapeutic predictors for gabapentin and to establish the prediction equation.

Results:

Gabapentin treatment achieved a therapeutic success rate of 66.48%. HARQ scores were significantly higher in responders than non-responders to gabapentin (29.79 ± 9.58 versus 21.95 ± 7.83, t = –3.685, p <0.001), which were positively related to the therapeutic efficacy of gabapentin (r = 0.433, p <0.001). The optimal cutoff point of 21.50 in HARQ presented with a moderate ability to predict gabapentin efficacy, with a sensitivity of 84.60% and specificity of 63.60%. Multiple logistic regression identified items of “A tickle in your throat, or a lump in your throat” (OR = 7.927, p = 0.005), “Cough when you get out of bed in the morning” (OR = 7.016, p = 0.045), and “Cough with eating” (OR = 6.689, p = 0.011) as independent predictors. The established logistic regression equation predicted 83.72% of the treatment success rate of gabapentin, which was verified by consequent preliminary revalidating study in 59 patients.

Conclusion:

HARQ may be useful to screen patients with CRC most likely responsive to gabapentin, and help improve the therapeutic success.

Trial registration:

http://www.chictr.org/; No.: ChiCTR-ONC-13003123

Management of chronic refractory cough in adults

Cough is a common respiratory symptom that is considered to be chronic when it lasts more than eight weeks. When severe, chronic cough may significantly impact an individual's quality of life, and such patients are frequently referred for specialist evaluation. Current international guidelines provide algorithms for the management of chronic cough: in most cases, treatment of the underlying disease is sufficient to improve or resolve cough symptoms. Severe chronic cough may significantly affect patients' quality of life and necessitate frequent referral for specialist evaluations. In this narrative review, we summarize non-pharmacologic and pharmacologic management of adult patients with chronic cough of known cause that persists after proper treatment (chronic refractory cough, CRC) or chronic cough of unknown cause in adult patients. If chronic cough persists even after treatment of the underlying disease, or if the chronic cough is not attributable to any cause, then a symptomatic approach with neuromodulators may be considered, with gabapentin as the first choice, and opioids or macrolides as alternatives. Speech pathology treatment and/or neuromodulators should be discussed with patients and alternative options carefully considered, taking into account risk/benefit. Novel promising drugs are under investigation (e.g. P2×3 inhibitors), but additional studies are needed in this field. Speech pathology can be combined with a neuromodulator to give an enhanced treatment response of longer duration suggesting that non-pharmacologic treatment may play a key role in the management of CRC.

Mechanisms and Rationale for Targeted Therapies in Refractory and Unexplained Chronic Cough

Chronic cough, defined as a cough lasting > 8 weeks, is a common medical condition that exerts a substantial physical, mental, and social burden on patients. A subset of patients with chronic cough are troubled with a cough that persists despite optimal treatment of presumed associated common and uncommon conditions (refractory chronic cough; RCC) or in which no diagnosable cause for cough can be identified despite extensive assessment (unexplained chronic cough; UCC). Many of these patients exhibit clinical features of cough hypersensitivity, including laryngeal paresthesia, hypertussia, and allotussia. Over-the-counter cough remedies are ineffective and can lead to intolerable side effects when used for RCC/UCC, and the lack of approved treatments indicated for these conditions reflects a major unmet need. An increased understanding of the anatomy and neurophysiology of protective and pathologic cough has fostered a robust clinical development pipeline of several targeted therapies for RCC/UCC. This manuscript reviews the mechanisms presumed to underly RCC/UCC together with the rationale and clinical evidence for several targeted therapies currently under clinical investigation, including transient receptor potential channel antagonists, P2X3-receptor antagonists, voltage-gated sodium channel blockers, neuromodulators, and neurokinin-1-receptor antagonists. Finally, we provide an overview of targets that have been investigated in preclinical models of cough and other airway diseases that may hold future promise for clinical studies in RCC/UCC. Development of targeted therapies with different sites of action may foster a precision medicine approach to treat this heterogeneous, underserved patient population.

The cognitive footprint of medication: A review of cognitive assessments in clinical trials

WHAT IS KNOWN AND OBJECTIVE

Polypharmacy is common, and many medications have cognitive side effects. Such effects can be transient and subside when the drug in question is discontinued or can be long-lasting with effects present for years afterwards. Although formal assessment of cognition is feasible and often undertaken in neuropsychiatric trials, these effects are usually neglected in the evaluation of any non-neuropsychiatric health intervention. Medication effects can be assessed within a cognitive footprint framework, to account for the magnitude and the duration of cognitive side effects, with some likely to have a greater and more lasting effect than others.

COMMENT

Adverse event reporting suggests that many medications may be indirectly associated with cognitive effects, for example due to headaches, somnolence and 'dizziness'; however, inferring causation from adverse event reporting can be problematic. In order to better understand the impact of investigational drug and concomitant medications effect on cognition, it would be essential to ensure cognition is prioritized in drug development evaluation. It is suggested that simple instruments that can be easily incorporated into existing trial designs are used to assess the cognitive footprint of medication.

WHAT IS NEW AND CONCLUSION

We present an overview of existing measures of cognition that can be integrated into drug trials in order to provide a cognitive footprint. Like quality of life testing, such tests should be administered as a standard throughout the key assessment stages of the design of the trial to ensure that any effects on this equally important outcome are also documented. Furthermore, employing routine cognition testing may also enable researchers to identify unanticipated beneficial and non-beneficial effects on cognition. Provision of such a cognitive footprint profile of drugs may provide the necessary evidence to enable decision-makers to make informed decisions on risk-benefit analysis that can subsequently make trade-offs between different drug regimens.

The management of chronic cough

Chronic cough is a common presentation to primary care and constitutes a significant volume of referrals to secondary care. It affects around 10% of the adult population and has a plethora of respiratory and non-respiratory causes. It can have a significant impact on the quality of life of affected individuals. In many patients, minimal baseline investigations lead to an easily identifiable and treatable cause. In others, no cause can be identified even after extensive investigations in specialized cough clinics. This evidence-based review article outlines the approach to the adult patient presenting with chronic cough and focuses upon current management strategies in those with chronic idiopathic cough. It includes results from trials of speech and language therapies, and the emerging concept of chronic idiopathic cough as a neuropathic disorder with its own bespoke approach to management including the use of neuromodulatory agents.

Effect of pregabalin for the treatment of chronic refractory cough: A case report

RATIONALE

Chronic refractory cough (CRC) is a common clinical problem which is more likely associated with some physical problems. Although many patients have received satisfactory treatment, there were still many patients suffered from long-term cough symptoms after standardized treatment.

PATIENT CONCERNS

A patient suffered from postherpetic neuralgia (PHN) and also he complained CRC for more than 20 years.

DIAGNOSIS

The patient was diagnosed with PHN and CRC.

INTERVENTIONS

Pregabalin was originally administered to treat PHN.

OUTCOMES

pregabalin not only alleviated her pain of PHN but also relieved chronic cough.

LESSONS

This report demonstrated the surprising effect of pregabalin on the treatment of CRC.

Danish respiratory society position paper: palliative care in patients with chronic progressive non-malignant lung diseases

Background: Chronic non-malignant lung diseases such as chronic obstructive pulmonary disease (COPD) and interstitial lung diseases (ILD) result in reduced quality of life (QoL), a high symptom burden and reduced survival. Patients with chronic non-malignant lung disease often have limited access to palliative care. The symptom burden and the QoL of these patients resembles patients with cancer and the general palliative approach is similar. However, the disease trajectory is often slow and unpredictable, and the palliative effort must be built on accessibility, continuity and professional competences. The Danish Health Authority as well as the WHO recommends that there is access to palliative care for all patients with life-threatening diseases regardless of diagnosis. In 2011, the Danish Health Authority requested that the national medical societies would to formulate guidelines for palliation.

Methods: In 2015, a group of members of the Danish Respiratory Society (DRS) was appointed for this purpose. It was composed of experienced ILD and COPD researchers as well as clinicians from different parts of Denmark. A literature review was made, a draft was prepared, and all recommendations were agreed upon unanimously.

Results: The Danish version of the position paper was finally submitted for review and accepted by all members of DRS.

Conclusion: In this position paper we provide recommendations on the terminology of chronic and terminal lung failure, rehabilitation and palliative care, advanced care planning, informal caregivers and bereavement, symptom management, the imminently dying patient, and organization of palliative care for patients with chronic non-malignant lung diseases.

An update and systematic review on drug therapies for the treatment of refractory chronic cough

INTRODUCTION

Chronic Cough (CC) is common and often associated with significant comorbidity and decreased quality of life. In up to 50% of cases, the cough is refractory despite extensive investigation and treatment trials. It is likely that the key abnormality in refractory CC is dysfunctional, hypersensitive sensory nerves, similar to conditions such as laryngeal hypersensitivity and neuropathic pain.

AREAS COVERED

The aim of this systematic review is to assess drug therapies for refractory CC. The authors review the current management of CC and provide discussion of the similarities between neuropathic pain and refractory CC. They review repurposed and new pharmacological treatments. Several meta-analyses were performed to compare the efficacy of treatments where possible.

EXPERT OPINION

Repurposed pain medications such as gabapentin and pregabalin reduce the frequency of cough and improve quality of life. Along with speech pathology, they are important and alternate treatments for refractory CC. However, more treatments are needed and the P2X3 ion channel receptor antagonists show the most promise. With a better understanding of neuronal activation and sensitisation and their signal processing in the brain, improved animal models of cough, and the use of validated cough measurement tools, more effective treatments will develop.

Symptomatic Treatment of Cough Among Adult Patients With Lung Cancer: CHEST Guideline and Expert Panel Report

BACKGROUND

Cough among patients with lung cancer is a common but often undertreated symptom. We used a 2015 Cochrane systematic review, among other sources of evidence, to update the recommendations and suggestions of the American College of Chest Physicians (CHEST) 2006 guideline on this topic.

METHODS

The CHEST methodologic guidelines and the Grading of Recommendations, Assessment, Development, and Evaluation framework were used. The Expert Cough Panel based their recommendations on data from the Cochrane systematic review on the topic, uncontrolled studies, case studies, and the clinical context. Final grading was reached by consensus according to the Delphi method.

RESULTS

The Cochrane systematic review identified 17 trials of primarily low-quality evidence. Such evidence was related to both nonpharmacologic (cough suppression) and pharmacologic (demulcents, opioids, peripherally acting antitussives, or local anesthetics) treatments, as well as endobronchial brachytherapy.

CONCLUSIONS

Compared with the 2006 CHEST Cough Guideline, the current recommendations and suggestions are more specific and follow a step-up approach to the management of cough among patients with lung cancer, acknowledging the low-quality evidence in the field and the urgent need to develop more effective, evidence-based interventions through high-quality research.

Alleviation of pain in painful diabetic neuropathy

INTRODUCTION

Painful diabetic neuropathy (PDN) is a disabling pain condition. Its pathomechanism remains unknown, but a sensitization and neuronal hyperexcitabilty have been suggested. Only symptomatic pharmacological pain management treatment is currently available.

AREAS COVERED

The origin of PDN is enigmatic, and the evidence-based therapeutic guidelines therefore consist only of antidepressants and antiepileptics as first-line recommended drugs. This article relates to a MEDLINE/PubMed systematic search (2005-2015).

EXPERT OPINION

The results of the meta-analysis from the aspect of the efficacy of amitriptyline, duloxetine, venlafaxine, gabapentin and pregabalin are favorable, but the placebo response rate is relatively high in patients with neuropathic pain. For personalization of the medication of PDN patients, the optimum dosing, the genotyping of the metabolizing enzymes and optimum biomarkers are needed. As concerns the future perspectives, specific sodium channel subtype inhibitors acting on peripheral nociceptive neurons or modified T-type voltage-gated calcium channel blockers may be promising targets for pharmaceutical innovations. Another attractive strategy for the treatment is based on the effects of monoclonal antibodies against nerve growth factor, sodium channels, specific receptor and cytokines. Botulinum toxin A, capsaicin patch and spinal cord stimulation therapies are the nearest future therapeutic options for the treatment of PDN patients.

Symptom management in the older adult: 2015 update

This article updates the 2002 Jamie von Roenn article about "the palliation of commonly observed symptoms in older patients, including pain, neuropsychiatric, gastrointestinal, and respiratory symptoms." When palliative care was last covered in Clinics in Geriatric Medicine, President George W. Bush had just signed the No Child Left Behind Act, Homeland Security was being established, Michael Jackson won the Artist of the Century Award at the American Music Awards, and gas cost $1.61 a gallon. What has changed in the last decade and a half?

Endogenous central suppressive mechanisms regulating cough as potential targets for novel antitussive therapies

Cough and the accompanying sensation known as the urge-to-cough are complex neurobiological phenomena dependent on sensory and motor neural processing at many levels of the neuraxis. In addition to the excitatory neural circuits that provide the positive drive for inducing cough and the urge-to-cough, recent studies have highlighted the existence of likely inhibitory central neural processes that can be engaged to suppress cough sensorimotor processing. In many respects, the balance between excitatory and inhibitory central cough control may be a critical determinant of cough in health and disease which argues for the importance of understanding the biology of these putative central inhibitory processes. This brief review summarises the current knowledge of the central circuits that govern voluntary and involuntary cough suppression and posits the notion of targeting central suppressive mechanisms as a treatment for disordered cough in disease.