Fluorescence Studies of the Dehydration of Cefadroxil Monohydrate*

Although cefadroxil does not exhibit the phenomenon of photoluminescence when dissolved in a fluid medium, the compound has been found to exhibit fluorescence in its solid‐state monohydrate crystal form. The monohydrate was found to exhibit complicated photoluminescence, where two different sets of emission spectra could be obtained upon irradiation with an appropriate excitation wavelength. One of these photophysical systems became strongly suppressed when the monohydrate was half‐dehydrated, and only one of the photophysical systems could be observed in this hemihydrate. In the fully dehydrated state, both photophysical pathways became almost totally suppressed, so that the nonsolvated cefadroxil became effectively nonfluorescentand the American Pharmacists Association J Pharm Sci 96: 2757-2764, 2007