Fluorescence determination of sulphobutylether-beta-cyclodextrin sodium inhuman plasma and urine by size-exclusion chromatography with inclusion complex formation

HPLC methods with fluorescence detection have been developed for the determ ination of sulphobutylether-beta -cyclodextrin sodium (SBECD), a novel exci pient for use with drugs of limited aqueous solubility, in human plasma and urine. SBECD contains no chromophore or fluorophore but can be detected by size-exclusion HPLC using excitation and emission wavelengths of 290 and 3 60 nm when l-naphthol is included in the mobile phase. The guest-host inclu sion complex SBECD forms with the l-naphthol restores the quenched fluoresc ence in the mainly aqueous environment of the mobile phase. Using simple so lid phase extraction, recoveries of 41% were obtained using aminopropyl car tridges for urine and of 69% using end-capped cyclohexyl cartridges for pla sma. These extracts were analysed using size exclusion HPLC. Both methods w ere precise, accurate and simple to perform. The working ranges were 4 to 2 00 mug mL(-1) and 50 to 1500 mug mL(-1) for plasma and urine respectively T he lower limits of quantification were 4 mug mL(-1) for plasma and 50 mug m L(-1) for urine. The methods were also selective; no significant interferen ces were observed in six different sources of plasma or urine, or from a ra nge of likely co-medicants.