Background: Pleurodesis is a treatment method that aims to create permanent adhesion between the pleural layers to prevent recurrent fluid or air accumulation in the pleural cavity. Talc, one of the most commonly preferred agents in this procedure, is widely used in clinical practice. In this study, a new talc formulation with a modified surface to impart antibacterial and analgesic properties was experimentally evaluated for the first time. The main objective of the study was to comparatively assess the inflammatory and fibrotic responses following standard talc and modified talc applications. Methods: Thirty-six 12-week-old female Wistar albino rats were simply randomly divided into three different groups: control (n = 12), standard talc (n = 12), and modified talc (n = 12). Under anesthesia, 1 mL of physiological saline containing 17 mg of talc was injected intrapleurally into the right hemithorax. The presence of pneumothorax after the procedure was assessed by chest radiography. After a 12-day follow-up period, the animals were euthanized. Bronchoalveolar lavage (BAL) fluid samples, blood samples, and lung and pleural tissue samples were collected for biochemical, histopathological, and immunohistochemical analyses. Results: Modified talc application resulted in a significant increase in both visceral and parietal pleural thickness (p < 0.05). Granulation tissue formation and collagen deposition were significantly higher in the modified talc group. In addition, TGF-β expression and CD68-positive macrophage count increased significantly in the modified talc group (p < 0.05). Inflammatory changes in the lung parenchyma were limited and not statistically significant. Conclusions: The modified talc formulation enriched with lidocaine and antibacterial agents produced a stronger inflammatory and fibrotic response compared to standard talc. These findings indicate that modified talc may increase the effectiveness of pleurodesis. Furthermore, the absence of significant lung parenchymal damage suggests that this treatment is locally effective and feasible. However, further long-term and advanced studies are needed to translate these results into clinical use.