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Introduction: Chronic cough has increasingly been recognized as a distinct clinical entity that affects a significant portion of the global population. Despite advancements in understanding its pathophysiology, treatment options remain limited. Opioid analgesics have long been used for cough, and some have proven clear antitussive potential. However, these have yet to be approved by regulatory authorities for the treatment of chronic cough. Several novel synthetic opioid modulators that demonstrated antitussive effects in early-stage studies also failed to translate into clinical practice., Areas Covered: This mini review aims to summarize the implications of opioid receptors in the development of cough medicines and highlight recent advances in opioid analgesics in cough trials. PUB MED/CINAHL/Web of Science/Scopus was searched (September 2024)., Expert Opinion: Our understanding of the precise sites of action and the involvement of peripheral opioid receptors in cough remains limited. Despite these gaps in knowledge, opioids remain a viable option for some patients until more novel effective treatments are available. Due to the frequent opioid side effects, new opioid derivatives with improved properties are needed. The development of tailored or biased delta-opioid receptor ligands and mixed agonists of opioid receptor-like 1/mu receptors may offer hope for new opioid-based drug discovery for chronic cough.

The aim of this trial was to assess the effectiveness of Sediflù, a medical device containing active herbal ingredients, on nocturnal and diurnal persistent coughs in children, with a duration of 3 to 7 days. Children with a dry and/or productive cough were enrolled in this prospective, interventional, multicenter, placebo-controlled, double-blind, randomized clinical study. Clinical efficacy was assessed through the evaluation of the soothing action of Sediflù against dry and/or productive coughing, both at night and during the day, and other effects of coughing associated with quality of sleep: frequency, child's quality of sleep, parental quality of sleep and severity. Treatment with Sediflù improved both night-time and day-time cough scores from day 2. The diurnal score also improved significantly in the Sediflù group at days 3 and 7. Sediflù syrup can be considered a valid treatment for cough management in younger children with upper respiratory tract infections, shortening the cough duration., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: CC-R and ER have been scientific advisors for Cinfa and speakers outside the objective of this work. CC-R has worked as principal investigator in clinical studies promotes by Cinfa. CN and MCC are principal investigator in this trial. The other author declares that they have no competing interest.

Background: Refractory or unexplained chronic cough disrupts quality of life and burdens health care systems around the world. The P2X3 receptor antagonist gefapixant is approved in many countries for its antitussive effects, but taste disturbances are a common adverse effect. Four newer, more selective P2X3 receptor antagonists have been developed to address this problem., Research Question: How does the benefit-risk profile vary across the five available P2X3 receptor antagonists?, Study Design and Methods: A systematic review and network meta-analysis was conducted to evaluate the efficacy of P2X3 receptor antagonists, including gefapixant, sivopixant, eliapixant, camlipixant, and filapixant. Primary outcomes were a reduction rate in 24-hour cough frequency and incidence of taste disturbance. Dose-response curves and median effective dose (ED 50 ) were calculated. Effect size at ED 50 was ranked according to the surface under the cumulative ranking curve. The confidence was evaluated by Confidence In Network Meta-Analysis., Results: Sixteen randomized controlled trials involving 4,904 participants were analyzed. The gefapixant regimen demonstrated an ED 50 of 90.7 mg/d for cough frequency reduction. Gefapixant showed the highest antitussive effectiveness at ED 50 (reduction rate in 24-hour cough frequency: median, 28.1%; 95% credible interval [CrI], 21.0%-35.6%; ranked 1 of 5; moderate certainty) but the highest prevalence of taste disturbance (absolute risk difference per 100 patients: median, 38; 95% CrI, 27-51; ranked 5 of 5; high certainty) and the highest prevalence of discontinuation. Camlipixant had a well-balanced profile (reduction rate in 24-hour cough frequency: median, 14.7%; 95% CrI, 5.4%-26.0%; ranked 3 of 5; low certainty; and taste disturbance; absolute risk difference per 100 patients; median, 2; 95% CrI, 1-6; ranked 2 of 5; low certainty). Placebo had a mean of 33.1% reduction in 24-hour cough frequency., Interpretation: When used at safe doses, gefapixant had a favorable risk-benefit profile compared with the other four agents. Camlipixant showed initial promise, which may be further investigated by phase III trials currently underway., Clinical Trial Registration: University Hospital Medical Information Network Center (UMIN-CTR); No. UMIN000050622; URL: https://center6.umin.ac.jp., Competing Interests: Financial/Nonfinancial Disclosures The authors have reported to CHEST the following: S. Y. has received overseas scholarships from the Japan Society for Promotion of Science. Y. K., Y. O., T. K., and H. M. received honoraria from Kyorin Pharmaceutical Co Ltd. A. N. received honoraria from Kyorin Pharmaceutical Co Ltd and MSD K.K. None declared (N. H., J. H., M. S., and Y. H.)., (Copyright © 2024 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background: Cough is a common clinical complaint in small animal practice with limited treatment options for chronic underlying conditions., Objectives: The present study aimed to evaluate the efficacy of three antitussive drugs in a novel, minimally invasive canine acute cough model., Methods: Five clinically healthy Beagles were used to create an acute cough model by administering sterile saline via a transtracheally placed central venous catheter. Single-dose antitussive effects of butorphanol, maropitant and Danpron were assessed. Cough frequency was measured before and at hourly intervals up to 3 h post-administration of each drug, with a linear mixed model used for statistical analysis., Results: Butorphanol (0.3 m/kg, IM) significantly reduced cough frequency at 1 and 3 h post-administration. Danpron (0.1 mL/kg, IM) also significantly reduced cough frequency 1 h post-administration; however, this effect was not sustained at 3 h. Maropitant (1 mg/kg, IM) did not significantly reduce cough frequency. The cough induction method was effective and minimally invasive, with no adverse effects., Conclusion: The present study demonstrated that butorphanol has a potent and prolonged antitussive effect in an acute canine cough model, whereas Danpron shows a transient effect. These findings provide valuable insights into the comparative efficacy of commonly used antitussive drugs in dogs., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Herbal medicines, particularly traditional Chinese medicines (TCMs), are a rich source of natural products with significant therapeutic potential. However, understanding their mechanisms of action is challenging due to the complexity of their multi-ingredient compositions. We introduced Herb-CMap, a multimodal fusion framework leveraging protein-protein interactions and herb-perturbed gene expression signatures. Utilizing a network-based heat diffusion algorithm, Herb-CMap creates a connectivity map linking herb perturbations to their therapeutic targets, thereby facilitating the prioritization of active ingredients. As a case study, we applied Herb-CMap to Suhuang antitussive capsule (Suhuang), a TCM formula used for treating cough variant asthma (CVA). Using in vivo rat models, our analysis established the transcriptomic signatures of Suhuang and identified its key compounds, such as quercetin and luteolin, and their target genes, including IL17A, PIK3CB, PIK3CD, AKT1, and TNF. These drug-target interactions inhibit the IL-17 signaling pathway and deactivate PI3K, AKT, and NF-κB, effectively reducing lung inflammation and alleviating CVA. The study demonstrates the efficacy of Herb-CMap in elucidating the molecular mechanisms of herbal medicines, offering valuable insights for advancing drug discovery in TCM., (© The Author(s) 2024. Published by Oxford University Press.)

Aim: To study the efficacy and safety of Eladis® in comparison with placebo in patients with non-productive cough., Materials and Methods: A phase III clinical trial enrolled 250 patients aged 18-65 years with acute respiratory viral infection with upper respiratory tract involvement or acute bronchitis. Patients were randomized into 2 groups of 125 subjects: group 1 received Eladis® (40 mg tablets), group 2 received a matching placebo. The patients received the study drugs 1 tablet BID for 7-14 days. After the treatment, patients were followed up (day 7±2) to assess the effect of therapy on the frequency of coughing attacks, the frequency and severity of daytime and nocturnal cough, the severity of cough, the duration of clinical cough cure, and the effect on the severity of the main acute respiratory viral infection symptoms., Results and Conclusion: The results of the study demonstrate the overall efficacy and statistically significant superiority of Eladis® over placebo: there were significant differences between the study groups in the proportion of patients who decreased the coughing attack frequency by ≥50% by day 5 ( p <0.0001). In addition, the clinical cure of cough in the Eladis® group occurred 2 days earlier: the median time was 6 days, vs 8 days in placebo group. There was a decrease in the frequency of cough attacks and a decrease in its severity by more than 3.5 points by day 5 of treatment. All the effects were associated with high safety of the drug.

Refractory chronic cough is a disabling disease with very limited therapeutic options. A better understanding of cough pathophysiology has led to the development of emerging drugs targeting cough receptors. Recent strides have illuminated novel therapeutic avenues, notably centred on modulating transient receptor potential (TRP) channels, purinergic receptors, and neurokinin receptors. By modulating these receptors, the goal is to intervene in the sensory pathways that trigger cough reflexes, thereby providing relief without compromising vital protective mechanisms. These innovative pharmacotherapies hold promise for improvement of refractory chronic cough by offering improved efficacy and potentially mitigating adverse effects associated with current recommended treatments. A deeper comprehension of their precise mechanisms of action and clinical viability is imperative for optimising therapeutic interventions and elevating patient care standards in respiratory health. This review delineates the evolving landscape of drug development in this domain, emphasising the significance of these advancements in reshaping the paradigm of cough management., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Ethnopharmacological Relevance: "Snow-white waterlily" (Nymphaea candida) dried flower possesses various efficacy in Uighur medicine such as reducing fever and nourishing the liver, anti-inflammatory and cough relieving, moistening the throat and quenching thirst., Aim of the Study: Polyphenols are characteristic component of N. candida as well as its quality markers, and the purpose of this study was to conduct investigations into anti-inflammatory, antitussive, antipyretic, and analgesic activities of the polyphenol-enriched fraction from N. candida (NCTP) in order to validate the traditional efficacy of this plant., Materials and Methods: The polyphenols in NCTP were analyzed by HPLC, and an acute oral toxicity study was conducted for NCTP. The anti-inflammatory activities of NCTP were evaluated using xylene induced ear edema, capillary permeability, cotton pellet granuloma, and carrageenan-induced rat paw edema, of which multiple biochemical indices were measured in carrageenan-induced rat paw edema such as prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2),5-lipoxygenase (5-LOX), interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) activities; the analgesic activities were investigated using acetic acid writhing, hot plate test, and formalin test; the anti-tussive and antipyretic effects were tested by ammonia induced cough in mice and yeast-induced fever respectively., Results: NCTP with LD50 of 5222 mg/kg was low toxicity and safety. NCTP (200 mg/kg) could significantly reduce ear swelling and capillary permeability by 30.63% and 31.37%, respectively. NCTP revealed 15.76% inhibiting activities in cotton pellet granuloma in mice at a dosage of 200 mg/kg. Furthermore, NCTP (50, 100, and 200 mg/kg) substantially decreased carrageenin-induced paw edema in rats between 1 and 5 h, and NCTP could decrease PGE2, 5-LOX, COX-2 levels as well as IL-6, IL-1β, TNF-α activities compared with the control group; NCTP could decrease MDA contents in carrageenin-induced rise, and increase SOD and GSH activities. Furthermore, the dose-dependent inhibition effect of NCTP on pain was revealed in the hot plate experiment. In addition to reducing the amount of writhes brought on by acetic acid, NCTP (50, 100, and 200 mg/kg) significantly inhibited pain latency against both stages of the formalin test. Moreover, NCTP (50, 100, 200 mg/kg) showed the better antitussive activities in mice in a dose-dependent manner. In the yeast-induced pyrexia test, dosages of 50, 100, and 200 mg/kg resulted in a statistically significant drop in rectal temperature., Conclusion: The experimental results proved the analgesic, anti-inflammatory, anti-tussive and antipyretic activities of the polyphenol-enriched fraction from N. candida, and supported the traditional use of this plant as well., Competing Interests: Declaration of competing interest All authors disclosed no relevant relationships, and confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: Codeine is a narcotic antitussive often considered for managing patients with refractory or unexplained chronic cough. This study aimed to evaluate the proportion and characteristics of patients who responded to codeine treatment in real-world practice., Methods: Data from the Korean Chronic Cough Registry, a multicenter prospective cohort study, were analyzed. Physicians assessed the response to codeine based on the timing and degree of improvement after treatment initiation. Follow-up assessments included the Leicester Cough Questionnaire and cough severity visual analog scale at six months. In a subset of subjects, objective cough frequency was evaluated following the initiation of codeine treatment., Results: Of 305 patients, 124 (40.7%) responded to treatments based on anatomic diagnostic protocols, while 181 (59.3%) remained unexplained or refractory to etiological treatments. Fifty-one subjects (16.7%) were classified as codeine treatment responders (those showing a rapid and clear response), 57 (18.7%) as partial responders, and 62 (20.3%) as non-responders. Codeine responders showed rapid improvement in objective cough frequency and severity scores within a week of the treatment. At 6 months, responders showed significantly improved scores in cough scores, compared to non-responders. Several baseline parameters were associated with a more favorable treatment response, including older age, non-productive cough, and the absence of heartburn., Conclusions: Approximately 60% of chronic cough patients in specialist clinics may require antitussive drugs. While codeine benefits some, only a limited proportion (about 20%) of patients may experience rapid and significant improvement. This underscores the urgent need for new antitussive drugs to address these unmet clinical needs., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: Farfarae Flos has the effect of cough suppression and phlegm elimination, with cough suppression as the main function. Studies have revealed that certain components of Farfarae Flos may be related to its cough suppressant effect, and some components have been confirmed to have cough suppressant activity. However, the antitussive material basis of Farfarae Flos has not been systematically elucidated. This study aims to elucidate the group of active ingredients in Farfarae Flos with cough suppressant activity by correlating the high performance liquid chromatography (HPLC) fingerprint of Farfarae Flos extract with its cough suppressant activity., Methods: HPLC was used to establish the fingerprint profiles of 10 batches of Farfarae Flos extract and obtain their chemical composition data. Guinea pigs were selected as experimental animals and the citric acid-induced cough model was used to evaluate the antitussive efficacy data of 10 batches of Farfarae Flos extract. SPF-grade healthy male Hartley guinea pigs were randomly divided into the S1 to S10 groups, a positive control group, and a blank control group (12 groups in total), with 10 guinea pigs in each group. The S1 to S10 groups were respectively administered Farfarae Flos extract S1 to S10 (4 g/kg), the positive control group was administered pentoverine citrate (10 mg/kg), and the blank control group was administered purified water. Each group received continuous oral administration for 5 days. The guinea pigs were placed in 5 L closed wide-mouth bottles, and 17.5% citric acid was sprayed into the bottle with an ultrasonic atomizer at the maximum spray intensity for 0.5 minutes. The cough latency period and cough frequency in 5 minutes were recorded for each guinea pig. Grey relational analysis (GRA) and partial least squares regression (PLSR) were used to conduct spectral-effect correlation analysis of the chemical composition data of Farfarae Flos extract and the antitussive efficacy data, and predict the group of active ingredients in Farfarae Flos with antitussive activity. The bioequivalence verification was conducted to verify the predicted group of active ingredients in Farfarae Flos with antitussive activity: SPF-grade healthy male Hartley guinea pigs were randomly divided into a S9 group, an active ingredient group, a positive control group, and a blank control group (4 groups in total), with 10 guinea pigs in each group. The S9 group was administered Farfarae Flos extract S9 (4 g/kg), the active ingredient group was administered the predicted combination of antitussive active ingredients (dose equivalent to 4 g/kg of Farfarae Flos extract S9), the positive control group was administered pentoverine citrate (10 mg/kg), and the blank control group was administered purified water. Each group received continuous oral administration for 5 days, and animal modeling and observation of efficacy indicators were the same as above., Results: The HPLC fingerprint of 10 batches of Farfarae Flos extract was established, and the peak area data of 14 main common peaks were obtained. The antitussive effect data of 10 batches of Farfarae Flos extract were obtained. Compared with the blank control group, the cough latence in the positive control group and S1, S2, S3, S4, S6, S7, S8, S9, S10 groups was prolonged (all P <0.01), while the cough frequency in 5 minutes in the positive control group and S1, S2, S4, S6, S8, S9, S10 groups was decreased (all P <0.05). The analysis of spectrum-effect relationship revealed that isochlorogenic acid C, isochlorogenic acid A, chlorogenic acid, isochlorogenic acid B, isoquercitrin, and rutin had high contribution to the antitussive effect of Farfarae Flos, and the 6 components were predicted to be the antitussive component group of Farfarae Flos. The verification of bioequivalence showed that there were no statistically significant differences in the antitussive effect between the S9 group and the antitussive component composition group(all P> 0.05), which confirmed that isochlorogenic acid C, isochlorogenic acid A, chlorogenic acid, isochlorogenic acid B, isoquercetin, and rutin were the antitussive component group of Farfarae Flos., Conclusions: The analysis of spectrum-effect relationship combined with the verification of bioequivalence could be used to study the antitussive material basis of Farfarae Flos. The antitussive effect of Farfarae Flos is the result of the joint action of many components.

In recent years, there has been a substantial increase in the development of antitussive therapies and the first new therapy, gefapixant has been licenced in Europe. This review describes current unlicenced treatments for chronic cough and details treatments currently in development for refractory chronic cough and cough in idiopathic pulmonary fibrosis, as well as compounds previously explored., (© 2023. The Author(s).)

Ethnopharmacological Relevance: Xingbei antitussive granules (XB) is a classic Chinese Medicine prescription for treating post-infectious cough(PIC), based on the Sanao Decoction from Formularies of the Bureau of People's Welfare Pharmacies in the Song Dynasty and Jiegeng decoction from Essentials of the Golden Chamber in the Han Dynasty. However, the therapeutic effects and pharmacological mechanisms are still ambiguous. In the present study, we endeavored to elucidate these underlying mechanisms., Aims of the Study: This study aimed to explore the potential impact and mechanism of XB on PIC, and provide a scientific basis for its clinical application., Materials and Methods: Cigarette smoking (CS) combined with lipopolysaccharide (LPS) nasal drops were administered to induce the PIC guinea pig with cough hypersensitivity status. Subsequently, the model guinea pigs were treated with XB and the cough frequency was observed by the capsaicin cough provocation test. The pathological changes of lung tissue were assessed by HE staining, and the levels of inflammatory mediators, mast cell degranulating substances, and neuropeptides were detected. The protein and mRNA expression of transient receptor potential vanilloid type 1(TRPV1), proteinase-activated receptor2(PAR2), and protein kinase C (PKC) were measured by Immunohistochemical staining, Western blot, and RT-qPCR. Changes in the abundance and composition of respiratory bacterial microbiota were determined by 16S rRNA sequencing., Results: After XB treatment, the model guinea pigs showed a dose-dependent decrease in cough frequency, along with a significant alleviation in inflammatory infiltration of lung tissue and a reduction in inflammatory mediators. In addition, XB high-dose treatment significantly decreased the levels of mast cell Tryptase as well as β-hexosaminidase (β-Hex) and downregulated the expression of TRPV1, PAR2, and p-PKC. Simultaneously, levels of neuropeptides like substance P (SP), calcitonin gene-related peptide (CGRP), neurokinin A (NKA), and nerve growth factor (NGF) were improved. Besides, XB also can modulate the structure of respiratory bacterial microbiota and restore homeostasis., Conclusion: XB treatment alleviates cough hypersensitivity and inflammatory responses, inhibits the degranulation of mast cells, and ameliorates neurogenic inflammation in PIC guinea pigs whose mechanism may be associated with the inhibition of Tryptase/PAR2/PKC/TRPV1 and the recovery of respiratory bacterial microbiota., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Background: Chronic cough (CC) affects about 10% of adults, but opioid use in CC is not well understood., Objectives: To determine the use of opioid-containing cough suppressant (OCCS) prescriptions in patients with CC using electronic health records., Design: Retrospective cohort study., Methods: Through retrospective analysis of Midwestern U.S. electronic health records, diagnoses, prescriptions, and natural language processing identified CC - at least three medical encounters with cough, with 56-120 days between first and last encounter - and a 'non-chronic cohort'. Student's t -test, Pearson's chi-square, and zero-inflated Poisson models were used., Results: About 20% of 23,210 patients with CC were prescribed OCCS; odds of an OCCS prescription were twice as great in CC. In CC, OCCS drugs were ordered in 38% with Medicaid insurance and 15% with commercial insurance., Conclusion: Findings identify an important role for opioids in CC, and opportunity to learn more about the drugs' effectiveness.

Renal fibrosis is a common pathway leading to progressive renal function loss in various forms of chronic kidney disease. Many fibrogenic factors regulate renal fibrosis; two key players are post-injury inflammation and transforming growth factor-β1 (TGF-β1)-induced myofibroblast differentiation. Myofibroblast differentiation is tightly regulated by the microtubule polymerization. Noscapine, an antitussive plant alkaloid, is a potent microtubule-interfering agent previously identified as a potential anticancer compound. Here, we examined how noscapine affects renal fibrogenesis in an in vitro renal fibroblast model and an in vivo unilateral ureteral obstruction (UUO) model. UUO mice were intraperitoneally treated with noscapine at 1 day before UUO surgery and daily thereafter. At 7 days post-surgery, kidneys were collected for further analysis. To analyze whether noscapine inhibits downstream TGF-β1-related signaling, we pre-incubated NRK-49F fibroblasts with noscapine and then performed TGF-β1 stimulation. In UUO mice, noscapine attenuated extracellular matrix protein deposition and the expression levels of type I collagen, type IV collagen, α-smooth muscle actin, and fibronectin. In addition, noscapine decreased tubulointerstitial inflammation in UUO kidneys by reducing TLR2 expression, modulating NLRP3 inflammasome activation, reducing macrophage infiltration, and antagonizing the M2 macrophage phenotype. Furthermore, noscapine pre-incubation suppressed the TGF-β1-induced fibroblast-myofibroblast transformation by downregulating the TGF-β/Smads signaling pathways in NRK-49F cells. These results suggest that noscapine reduces tubulointerstitial inflammation and fibrosis in the kidneys of UUO mice and inhibits the fibroblast-myofibroblast transformation induced by TGF-β1. Noscapine is an over-the-counter antitussive that has been used safely for several decades. Therefore, noscapine is an attractive therapeutic agent for inhibiting renal tubulointerstitial fibrosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)