Effects of Edaravone Treatment on Endometriotic Lesion Sizes in a Surgically Induced Rat Model: A Pilot Study

Endometriosis is a chronic, oestrogen-dependent inflammatory disorder associated with elevated systemic oxidative stress. Current medical therapies are limited by significant side effects and high recurrence rates, underscoring the need for novel therapeutic strategies. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a clinically approved synthetic free radical scavenger with established antioxidant and anti-inflammatory properties, representing a candidate for drug repurposing in endometriosis.

Ten female Wistar Albino rats underwent surgical endometriosis induction using the Vernon and Wilson method. After four weeks, lesion sizes were measured at a second laparotomy using a digital calliper (baseline). Animals were randomly allocated to an edaravone-treated group (n=6; 3 mg/kg/day subcutaneously for 28 days) or a saline control group (n=4). Lesion sizes were re-measured at a third laparotomy and tissue samples were collected for histological examination (haematoxylin and eosin staining). Between-group changes were compared using the Mann-Whitney U-test.

In the edaravone group, mean lesion size decreased from 2.40 ± 0.52 mm to 1.91 ± 0.54 mm (mean change: -0.50 mm; -17.0%). In the control group, mean lesion size increased from 4.47 ± 1.89 mm to 4.79 ± 2.02 mm (mean change: +0.32 mm; +7.09%). Baseline lesion size was larger in the control group than in the edaravone group, and this imbalance should be considered when interpreting the findings. The between-group difference in absolute lesion size change was statistically significant (Mann-Whitney U-test, p = 0.0095; rank-biserial r = 1.00), although the within-edaravone change was not statistically significant (p = 0.3125) and the between-group difference in percentage change did not reach significance (p = 0.114). Histological examination revealed active endometrial glands within fibrous stroma in control animals, whereas edaravone-treated implants showed predominantly fibrotic tissue with markedly reduced or absent glandular structures.

In this pilot study, edaravone-treated animals showed reduced lesion size relative to controls; however, the within-group reduction was not statistically significant, baseline lesion size differed between groups, and no mechanistic markers were measured. These preliminary, hypothesis-generating findings should be interpreted with caution and warrant larger, adequately powered, mechanistically comprehensive studies before any therapeutic potential of edaravone in endometriosis can be inferred.