A review of chromatographic methods used in the determination of anastrozole levels

Owing to the efficacy and popularity of anastrozole in the treatment of estrogen receptor-positive breast cancer, interest in analytical methods for its quantitative measurement both in pharmaceutical dosage formulations and Biological samples has risen sharply for a decade. This paper reviews the existing chromatographic methods, which are based on two popular detection methods: high performance liquid chromatography and gas chromatography mass spectrometry. The Current high performance liquid chromatography methods with UV detection so far reported; focus primarily on determining the concentration of anastrozole in pharmaceutical dosage formulations. However, such methods are insufficient in measuring the concentrations yielded in biological samples when the relatively low doses (1 mg daily) recommended for breast cancer treatment are used. Therefore, there is limited applicability of HPLC-UV detection methods for quantitative measurements of anastrozole in biological samples. A number of methods combining liquid chromatography with tandem mass spectrometry with limits of quantitation as low as 0.05 ng/ml have been developed for anastrozole measurement in plasma. A few methods on active pharmaceutical ingredients have also been reported. On the other hand, only a few gas chromatography methods have successfully been developed for the determination of anastrozole concentrations. In majority of the methods, where relevant, parameters such as selectivity, linearity, limit of detection, limit of quantitation, and accuracy have been considered, and recovery assessments during accuracy evaluation are generally satisfactory, with reported values ranging between 81 and 109%. However, a significant number of these studies did not use an internal standard to correct for the area of anastrozole, making their accuracies questionable. Overall, the current available detection methods for anastrozole are inadequate, and improved method validation techniques as well as simple and affordable anastrozole quantification methods in both pharmaceutical dosage formulations and especially biological samples are needed.