Evaluation of Drug-Excipient Compatibility of Ibuprofen with Eggshell-Derived Calcium Citrate Using FTIR, DSC, and Molecular Docking Studies

Abstract Ethnomedicinal Relevance : The use of eggshells for nutritional and medicinal purposes has long been documented in African folklore, where crushed or powdered shells are traditionally administered to enhance bone strength, treat calcium deficiency, and promote general well-being. Despite this ethnomedicinal relevance, their potential application as pharmaceutical excipients remains underexplored. Background : Drug-excipient incompatibilities are critical considerations in the development of stable and effective pharmaceutical formulations. This study investigated the compatibility of ibuprofen with eggshell-derived calcium citrate using Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and molecular docking approaches. Methods : Calcium citrate was prepared from chicken eggshells via reaction with citric acid and characterised. Binary mixtures of ibuprofen and calcium citrate were evaluated for potential interactions using FTIR and DSC. In silico molecular docking studies were conducted using AutoDock Vina, and docking methodology was validated using re-docking of a known ibuprofen-calcium interaction. Results : FTIR spectra of the binary mixtures showed minor peak shifts, particularly at 1710 cm⁻¹ (C=O) and 3300 cm⁻¹ (O-H), suggesting weak physical interactions. DSC thermograms demonstrated slight broadening and depression of the ibuprofen melting endotherm, indicating no significant incompatibility. Molecular docking revealed a binding affinity of -4.7 kcal/mol, primarily mediated by ionic interactions between ibuprofen’s carboxyl group and calcium ions. Conclusion : Ibuprofen exhibits acceptable compatibility with eggshell-derived calcium citrate. These findings suggest its potential as a sustainable and cost-effective pharmaceutical filler in oral drug formulations.