BACKGROUND: The benefits and harms of adding antileukotrienes to H1 antihistamines (AHs) for the management of urticaria (hives, itch, and/or angioedema) remain unclear.
OBJECTIVE: We sought to systematically synthesize the treatment outcomes of antileukotrienes in combination with AHs versus AHs alone for acute and chronic urticaria.
METHODS: As part of updating American Academy of Allergy, Asthma & Immunology and American College of Allergy, Asthma, and Immunology Joint Task Force on Practice Parameters urticaria guidelines, we searched Medline, Embase, Central, LILACS, WPRIM, IBECS, ICTRP, CBM, CNKI, VIP, Wanfang, US Food and Drug Administration, and European Medicines Agency databases from inception to December 18, 2023, for randomized controlled trials (RCTs) evaluating antileukotrienes and AHs versus AHs alone in patients with urticaria. Paired reviewers independently screened citations, extracted data, and assessed risk of bias. Random effects models pooled effect estimates for urticaria activity, itch, wheal, sleep, quality of life, and harms. The GRADE approach informed certainty of evidence ratings. The study was registered at the Open Science Framework (osf.io/h2bfx/).
RESULTS: Thirty-four RCTs enrolled 3324 children and adults. Compared to AHs alone, the combination of a leukotriene receptor antagonist with AHs probably modestly reduces urticaria activity (mean difference, -5.04; 95% confidence interval, -6.36 to -3.71; 7-day urticaria activity score) with moderate certainty. We made similar findings for itch and wheal severity as well as quality of life. Adverse events were probably not different between groups (moderate certainty); however, no RCT reported on neuropsychiatric adverse events.
CONCLUSIONS: Among patients with urticaria, adding leukotriene receptor antagonists to AHs probably modestly improves urticaria activity with little to no increase in overall adverse events. The added risk of neuropsychiatric adverse events in this population with leukotriene receptor antagonists is small and uncertain.

BACKGROUND: Post-marketing surveillance found montelukast use was associated with an increased risk of depression. However, results of observational studies are inconsistent.
OBJECTIVE: This study aimed to assess whether montelukast exposure is associated with depression and elucidate the possible molecular mechanism.
METHODS: We conducted a cross-sectional study of 9508 adults from the National Health and Nutrition Examination Survey (NHANES) 2007-2016. Multivariable regression was used to evaluate the association between montelukast exposure and depression. Network pharmacology was conducted to identify the mechanisms of montelukast on depression.
RESULTS: Montelukast exposure had a higher prevalence of depression (37.4 %). In a multivariable logistic regression model adjusted for sociodemographic, behavioural, and health characteristics, montelukast exposure was associated with depression (odds ratio [OR]: 1.61; confidence interval [CI]: 1.18-2.19). Network pharmacology was identified 69 key targets of montelukast on depression. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis suggested montelukast mainly works through multiple pathways in endocrine resistance, chemical carcinogenesis-receptor activation, estrogen signaling pathway, etc. LIMITATIONS: Cross-sectional data.
CONCLUSIONS: The study implies a potential positive association between long-term montelukast exposure and depression through multi-faceted mechanisms. It is suggested that attention be given to the possibility of depression in patients undergoing prolonged montelukast therapy.

BACKGROUND: Post-market monitoring has shown a potential link between the use of leukotriene-modifying agents (LTRAs) and an increased risk of neuropsychiatric events, such as depression. However, observational studies have produced inconsistent findings, offering no definitive conclusions.
OBJECTIVE: To assess the potential correlation between LTRAs exposure and depression in US adults.
METHODS: This cross-sectional study, based on population data from the National Health and Nutrition Examination Survey (NHANES) 2007-2016 cycle. The Patient Health Questionnaire-9 was used to assess depression. Multivariable regression was used to evaluate the association between LTRAs exposure and depression. Sensitivity and subgroup analyses were conducted, with the calculation of the E-value. Network pharmacology was employed to investigate the influence of LTRAs on mechanisms of depression.
RESULTS: Among the 9414 participants, 595 (6.3 %) were classified as having depression. LTRAs exposure was associated with a higher prevalence of depression (16.9 % vs. 6.0 %). The multivariable logistic regression results showed that LTRAs use increased the risk of depression (OR = 1.70; 95 % CI, 1.05-2.75). An association between LTRAs exposure and depression was found in sensitivity analyses conducted regardless of multivariable linear regression with the PHQ-9 score as a continuous variable (β = 0.97; 95 % CI, 0.44-1.50) or multivariable logistic regression with the PHQ-9 cut-off of 5 (OR = 1.52; 95 % CI, 1.08-2.14). The association between LTRAs and depression was stable in the different subgroups.
CONCLUSIONS: LTRAs exposure is positively associated with depression in US adults. Therefore, the risk for depression in patients receiving long-term LTRAs treatment should be considered.

Cysteinyl leukotriene receptor 1 (CYSLTR1) is observed to increase in psoriatic skin lesions. Montelukast, a CYSLTR1 antagonist, effectively treats inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis, and atopic dermatitis. Thus, blocking CYSLTR1 may be a promising strategy for psoriasis immunotherapy. We prepared a montelukast sodium cream and solution and investigated their effects on psoriasis-like skin lesions induced by imiquimod (IMQ). After the treatment, serum, skin, and spleen samples were collected for evaluation. We treated human T helper (Th) 17 cells with montelukast in vitro to study its effect on Th17 differentiation and nuclear factor kappa-B (NF-κB) signaling. We also created a keratinocyte proliferation model induced by M5 cytokines and assessed the influence of montelukast on key psoriasis-related genes. We induced psoriasis in CYSLTR1 knockout (KO) mice using IMQ to explore the role of CYSLTR1 in psoriasis development. Montelukast sodium cream and solution effectively reduced the psoriasis area and severity index (PASI) and alleviated disease symptoms in IMQ-induced mice. Furthermore, reduced infiltration of inflammatory cells (Th1, Th17, and T follicular helper [Tfh] cells), decreased mRNA expression of cytokines in the skin (interleukin [IL]-17/F and IL-23), and lower serum concentrations of various cytokines (IL-2, IL-6, IL-13, and IL-17A/F) were observed. Montelukast cream and solution also decreased spleen size and the proportion of Th17 and Tfh cells, and significantly inhibited NF-κB signaling-related genes after application. Moreover, montelukast inhibited Th17 cell differentiation and suppressed NF-κB signaling in vitro. CYSLTR1 KO mice induced with IMQ showed improvement in PASI scores, serum IL-17A/F levels, and lower Th1 and Th17 cells in the spleen and skin compared to wild-type mice. Montelukast also suppressed the proliferation and inflammatory response of keratinocytes by regulating NF-κB signaling. Collectively, our results strongly indicate that inhibition of CYSLTR1 signaling to target the Th17 response holds significant promise as a therapeutic approach to manage psoriasis.

Background: Montelukast (MTK), a potent antagonist of cysteinyl leukotriene receptor 1, has shown therapeutic promise for the treatment of neuropsychiatric disorders. Delirium, a common complication in critically ill patients, lacks effective treatment. This study aims to explore the impact of pre-intensive care unit (ICU) MTK use on in-hospital delirium incidence and, subsequent, prognosis in critically ill patients. Methods: A retrospective cohort study (n = 6344) was conducted using the MIMIC-IV database. After propensity score matching, logistic/Cox regression, E-value sensitivity analysis, and causal mediation analysis were performed to assess associations between pre-ICU MTK exposure and delirium and prognosis in critically ill patients. Results: Pre-ICU MTK use was significantly associated with reduced in-hospital delirium (OR: 0.705; 95% CI 0.497-0.999; p = 0.049) and 90-day mortality (OR: 0.554; 95% CI 0.366-0.840; p = 0.005). The association was more significant in patients without myocardial infarction (OR: 0.856; 95% CI 0.383-0.896; p = 0.014) and could be increased by extending the duration of use. Causal mediation analysis showed that the reduction in delirium partially mediated the association between MTK and 90-day mortality (ACME: -0.053; 95% CI -0.0142 to 0.0002; p = 0.020). Conclusions: In critically ill patients, MTK has shown promising therapeutic benefits by reducing the incidence of delirium and 90-day mortality. This study highlights the potential of MTK, beyond its traditional use in respiratory disease, and may contribute to the development of novel therapeutic strategies for delirium.

Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in preterm infants and lacks effective methods for prevention and treatment. The aim of this study is to explore the efficacy and safety of montelukast in preventing or treating BPD in preterm infants. The preterm infants with BPD risk factors were divided randomly into a montelukast group and a control group. In the montelukast group, preterm infants were given 1 mg/kg of montelukast sodium daily. There was no placebo in the control group. There was no significant difference in the incidence of moderate or severe BPD between the two groups (31.8% vs. 35%). The duration of respiratory support in the montelukast group was shorter than that in the control group (36.4 ± 12.8 d vs. 43.1 ± 15.9 d, p = 0.037). The pulmonary severity score (PSS) at 21 days of life in the montelukast group was significantly lower than that in the control group (0.56 ± 0.13 vs. 0.62 ± 0.14, p = 0.048). There were no significant differences in the duration of mechanical ventilation, length of stay, hospitalization expenses, or incidence of adverse events. Although montelukast cannot alleviate the severity of BPD, it may shorten the duration of respiratory support and decrease the PSS in very preterm infants. There were no significant adverse drug events associated with montelukast treatment.

OBJECTIVE: This study aimed to evaluate the efficacy and safety of montelukast (Mon) + fluticasone propionate (Flu) versus Flu in the treatment of cough variant asthma (CVA) in children.
METHODS: Eligible documents were selected from various databases. Weighted mean difference (WMD) and 95% confidence interval (CI) were used to evaluate continuous variables, and categorical variables were evaluated using risk ratio (RR) and 95% CI. Heterogeneity analysis was performed using Cochran\'s Q test and I2 statistics, followed by sensitivity analysis and publication bias evaluation.
RESULTS: Nine studies were included, and Flu + Mon was found to significantly improve the total effective rate and reduce cough recurrence compared to Flu. The cough remission and disappearance times in the Mon + Flu group were significantly lower than those in the Flu group. FEV1% recovery in the Mon + Flu group was significantly better than that in the Flu group.
CONCLUSIONS: Mon + Flu is effective and safe for the treatment of CVA in children.

Use of montelukast, as a cause of neuropsychiatric events, in patients with asthma or allergic rhinitis is controversial, and comprehensive statistical analyses verifying this relationship remain lacking. To better understand the relationship between montelukast and neuropsychiatric events, it is vital to guide patients in the effective use of the drug, especially in children whose mothers are concerned about its side effects. In this study, randomized controlled trials (RCTs) investigating montelukast and neuropsychiatric events were retrieved from a literature search of the Medline (1966 to February 2023), Embase (1974 to February 2023), Web of Science, and other related databases. After screening, 18 RCTs were ultimately included in a meta-analysis to merge statistics, which demonstrated no significant increase in neuropsychiatric events compared with placebo. A similar pattern of adverse neuropsychiatric events was observed in patients grouped according to age, with headache being the most common adverse neuropsychiatric event. Overall, montelukast did not significantly increase neuropsychiatric events in patients with allergic rhinitis and/or asthma compared with placebo. Large-sample RCTs are needed to verify the association between neuropsychiatric events and montelukast use in children, and attention is also devoted to FDA warnings.

Background: Adenoidal hypertrophy (AH) is one of the most common causes of upper airway obstruction in children. Drug and surgical treatment are the typical treatment of AH. The study on the inflammatory mechanism of AH in children provides a new idea for preoperative intervention and non-surgical treatment with anti-inflammatory drugs such as montelukast sodium (a cysteine leukotriene receptor antagonist). The aim of this study is to evaluate the effect of montelukast sodium on adenoidal lymphoid tissue pathology in children with AH under light microscope. Objective: To study whether there is any change in pathology of the adenoidal lymphoid tissue under the light microscope compared with the control group in children with moderate to severe simple AH treated with montelukast sodium for 1 month before operation. Materials and methods: Twenty patients (8 males, 12 females, 3-8 years old) with moderate to severe AH who were prepared for surgical treatment were selected. All the patients were examined by Nasopharyngeal CT and hemocyte analysis before operation. 20 subjects were randomly divided into two groups: One group was given montelukast chewable tablets 5 mg/d, qn, for 4 weeks; The control group was given placebo 5 mg/d, qn, for 4 weeks. After 4 weeks, the adenoids were removed and examined histopathology. Results: Compared with the control group, the number of lymphocytes in the blood cell analysis of the study group was significantly reduced, with a statistically significant difference (p < 0.05). And the number of germinal centers in adenoid tissue of the study group was relatively reduced, no small cyst was found in the epithelium, and the degree of inflammatory cell infiltration was reduced, with a statistically significant difference (p < 0.05). Conclusion: Montelukast can reduce the number of reactive cells, the number of lymphocytes in blood cells and blood vessels in adenoid lymphoid tissue, which can provide a new idea for preoperative intervention and non-surgical treatment of adenoid hypertrophy in children. However, this is only a pilot study and a longer treatment period is needed to assess the long-term effects of montelukast sodium on adenoid lymphoid tissue. Clinical Trial Registration: www.Chictr.org.cn, identifier ChiCTR2300075040.

Pancreatic cancer is one of the most lethal cancer types with 5-year survival rate of ∼10.8%. Various KRAS mutations exist in ∼85% pancreatic cancer cell lines. Mutated KRAS is a major cause that leads cancer cell proliferation. Chemotherapy is still the major treatment for pancreatic cancer. Alternatively, repositioning old drug to inhibit mutated KRAS may be a cost-effective way for pancreatic cancer treatment. In this study, we choose mutated KRAS (G12D) as a target. Based on mutated KRAS GTP binding domain (hydrolyze GTP to GDP), we perform virtual screening on FDA-approved drugs. Montelukast shows strong binding affinity to mutated KRAS as well as interfering both GTP and GDP binding to mutated KRAS. Furthermore, Montelukast shows very strong anti-proliferation effect on mutated KRAS pancreatic cancer cells both in vitro and in vivo. Our results support repositioning of Montelukast as single agent for pancreatic cancer treatment.