Development and validation of high performance liquid chromatographic and derivative spectrophotometric methods for determination of gadodiamide in liposomal formulations

Gadodiamide is a complex of gadolinium (Gd), whose structure presents two carboxylate groups of diethylenetriaminepentaacetic acid (DTPA) substituted by two amide groups (BMA). The use of liposomes as carriers of gadodiamide (Gd-DTPA-BMA) has shown great potential for cancer therapy. In this study, two methods using high performance liquid chromatography (HPLC) without derivatization and derivative spectrophotometry (DSUV) were developed and validated for determination of Gd-DTPA-BMA in liposomes. No interference was observed by using the HPLC method. Also, the third-order derivative has eliminated the interference from the lipid formulations. The methods have shown to be selective, precise, accurate, and linear in the range of 0.1-0.5 mu mol mL(-1) for HPLC and 25-285 mmol mL(-1) for DSUV. The limits of quantification were 3.50 x 10(-2) mu mol mL(-1) for HPLC and 18.33 mmol mL(-1) for DSUV, while the limits of detection were 2.02 x 10(-)2 mu mol mL(-1) and 12.42 mmol mL(-1) for HPLC and DSUV, respectively. Both methods were employed to determine the concentrations of Gd-DTPA-BMA entrapment in three liposomal formulations with different characteristics. No significant difference was found between the results obtained by the developed methods. HPLC and DSUV methods presented advantages over existing methodologies, such as simplicity, speed, low cost, and applicability to the characterization of liposomes containing Gd-DTPA-BMA.