Cefdinir: A comparative study of anhydrous vs. monohydrate form: Microstructure and tabletting behaviour

Anhydrous cefdinir (AC) vs. monohydrated cefdinir (MHC) was compared in order to be used as antimicrobial in therapeutics. Different techniques have been used to characterize physically AC and MHC, and also a complete microstructural analysis of raw materials was carried out. Cefdinir and Maltodextrin QDM® 500 (3:2) formulations were compressed in order to obtain tablets with typical dose of Cefdinir, i.e. 300 mg. Dissolution profiles were obtained for both AC and MHC tablets. Finally tablet X-ray diffraction was performed to ensure the stability of the monohydrated form after tabletting being clearly different in both AC and MHC crystals. AC crystal structure was agreed with the known pattern of anhydrous Cefdinir described in the literature. Microstructural analysis showed large differences in specific surface area (SSA), confirmed by mercury intrusion. Crystal structures of both AC and MHC were stable under mixing, compression and storing processes. Dissolution profiles were faster for hydrate form, probably related to microstructural properties of the crystal which remained after tabletting. In conclusion, it is possible to isolate Cefdinir in two forms anhydrous and monohydrate, well characterized and differentiated. The use of this later improves dissolution of tablet dosage form due to the lack of interconversion during tablet manufacture.