[Jan 2025] Montelukast may help prevent cardiac fibrosis. Cardiac fibrosis is a major cause of heart failure.  

A number of Chinese universities coordinated in a study published by the European Journal of Pharmacology in 2022. In tranverse aortic constricted mice, they found that montelukast improved cardiac pumping function and inhibited cardiac fibrosis by down-regulation of the proteins related to the fibrosis.

Montelukast was found to reduce the production of proteins like connective tissue growth factor (CTGF), transforming growth factor β (TGF-β), and alpha-smooth muscle actin (α-SMA). 

Montelukast was also found to reduce the number of cells that are proliferating during the fibrosis process and also reduce the amount of collagen production.

https://pubmed.ncbi.nlm.nih.gov/35358494/

In another study conducted by the Department of Pharmaceutical Sciences, University of Milan, Italy was published in Nature in 2024. In the study, mice of a type used as a model of myocardial infarction were subjected to coronary artery ligation and received montelukast. The montelukast treated mice received beneficial effects in the infarcted area and had improved cardiac pumping action when compared to the untreated mice. The results provided evidence for repurposing montelukast for cardiac diseases.

Unfortunately even though there is much evidence by using animal models that montelukast is effective in treating cardiac diseases, the difficulty lies in getting governments and institutions to sponsor clinical trials. Certainly the pharmaceutical industry is not interested in spending money on a generic drug clinical trial.

https://www.nature.com/articles/s41598-024-53936-x

[Mar 2025] An investigation was done in Japan in 2010 to test the effectiveness of montelukast in alleviating the symptoms of dysmenorrhea (moderate to severe  menstrual pain).

Study design
This prospective, double-blind, randomized, placebo-controlled study was comprised of 62 patients with dysmenorrhea who were randomly divided into 2 groups (montelukast 10 mg taken 4 times a day and the placebo group). Data obtained from 50 patients were analyzed (montelukast: 24; placebo: 26). Using visual analog scale (VAS) scores and nonsteroidal anti-inflammatory drug (NSAID) usage per menstrual cycle, values before treatment were compared to average scores over two menstrual cycles with treatment.

Results
Both the VAS scores and NSAID usage decreased significantly in both groups. The decreases were greater in the montelukast group compared to the placebo group, but the differences were not statistically significant. Nevertheless, in “highly effective cases,” which were defined as having a post-treatment value less than half of the pre-treatment value, the decreases were significantly greater in the montelukast group than in the placebo group (VAS: montelukast, 4 vs. placebo, 0 (P = 0.029); NSAID: montelukast, 9 vs. placebo, 3 (P = 0.031)).

Conclusions
The present study found that montelukast may be effective in alleviating pain associated with dysmenorrhea in some women. Montelukast is safe and does not influence hormonal levels. Therefore, montelukast is a clinically reasonable management option to consider before prescribing a hormonal agent.

This trial got it right by giving an effective dosage of 10 mg 4 times a day. Unfortunately many clinical trials for other conditions have used the ineffective dosage of 10 mg once a day, which is the approved dosage for asthma. Merck really got it wrong when it submitted this low dosage to the FDA for approval 25 years ago. Montelukast, which has a half life of only about 4 hours, could have been a much more effective asthma drug at 10 mg twice or three times a day. 

https://www.sciencedirect.com/science/article/abs/pii/S0301211509006460