Repurposing Clotrimazole for Pancreatic Ductal Adenocarcinoma: Comparative In Vitro Evaluation and In Silico ADMET Context

Background: Clotrimazole (CLZ) is an approved antifungal with reported pleiotropic effects. Beyond its antifungal use, CLZ can perturb glycolytic flux and ionic homeostasis, motivating its evaluation as a repurposing candidate in oncology. Objective: We aimed to evaluate CLZ and nitazoxanide (NTZ) as drug repurposing candidates for pancreatic ductal adenocarcinoma (PDAC) in comparison with standard chemotherapeutics gemcitabine (GEM) and 5-fluorouracil (5-FU). Methods: T3M4 PDAC cells were treated (0.1–100 µM; 48–72 h) with 5-FU, GEM, CLZ, and NTZ. Cell viability (MTT) and morphology were assessed, and CLZ-based combinations were analyzed by the Chou–Talalay method. In silico studies provided physicochemical descriptors and ADMET profiles, along with predicted interactions with relevant bioorganic targets (e.g., KCa3.1/KCNN4 ion channels). Results: CLZ produced marked cytotoxicity at 72 h (IC50 ≈ 9 µM) and achieved a greater reduction in cell viability at higher concentrations compared to 5-FU and GEM under identical conditions, whereas NTZ showed modest and inconsistent effects. CLZ combinations with 5-FU or GEM were mainly antagonistic. In silico analyses indicated high membrane permeability and suggested potential interactions with KCa3.1, supporting a hypothesis-generating interpretation of the observed in vitro effects. Conclusions: Within a drug repurposing framework, CLZ exhibited consistent cytotoxic activity as a single agent in a PDAC cell model, whereas NTZ revealed limited effects and CLZ-based combinations were not beneficial under the tested conditions. These findings position CLZ as a monotherapy-oriented repurposing candidate for PDAC and motivate further mechanistic and translational studies to clarify the biological basis of its in vitro activity.