Affiliation: Departamento de Farmacia, Faculdade de Ciencias Farmaceuticas, Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 580, Cidade Universitaria, 05508-000, Sao Paulo, SP, Brasil.
This work aims to develop and validate a UPLC stability indicating method for quantitative analysis of Caspofungin, grounded in statistical analysis able to estimate measurement uncertainty, and determine drug degradation kinetics. The validation was performed as recommended in ICH guidelines. The chromatographic method was conducted applying the following conditions: 220 nm wavelength, 10 μL injection volume, 25 °C oven temperature, 0.6 mL/minute flow, and gradient elution involving mobile phases A and B, composed of 0.1 % solution of triethylamine pH adjusted to 2.5 with the aid of phosphoric acid and acetonitrile, respectively. The validation of the UPLC method demonstrated the selectivity, robustness, linearity, precision, accuracy and the ability to indicate caspofungin stability. Statistical analysis demonstrated the method is linear in the concentration range between 20 and 80 μg/mL (y= 30908912.1196x – 11246.7143; r= 0.9997), precise (repeatability: 1.09%, intermediate precision: 1.79%) and accurate (recovery range: 95.61–101.36%). According to these results, the uncertainties associated with accuracy and precision were the most significant, contributing to 57% overall uncertainty. On the other hand, repeatability of sample and standard peak areas were almost insignificant (less than 5% of overall uncertainty). The analysis of measurement uncertainty proved to be useful for validating the results and a very useful tool in routine analysis. The degradation kinetics were calculated using the UPLC method, which is a validated and well-established technique, capable of indicating thermal stability (80 °C) of caspofungin in solution. The drug kinetics of degradation showed a first order reaction (y = - 0.0078 x + 2.0168, r = 0.9993) and half-life (t1/2) estimated at 3.9-minute analysis under the conditions tested, indicating that caspofungin is strongly sensitive to heat stress condition.