Um método indicador de estabilidade por cromatografia líquida foi desenvolvido e validado para a análise de Nistatina (Nys) em uma pomada, uma vez que os métodos microbiológicos tradicionais não têm a habilidade de serem indicadores de estabilidade. A nistatina degradou significativamente em condições alcalinas e ácidas e também em meio oxidante. Quando a amostra foi exposta a luz de xenônio, foram observados menores níveis de degradação. A resolução entre os picos cromatográficos de Nys e seus produtos de degradação (PD) foi maior que 2, utilizando-se uma coluna Inerstil ODS-3, eluição isocrática com metanol: água e detecção no UV em 305 nm. O sistema foi linear entre a faixa de 102 a 310 UI mL-1 e preciso uma vez que o DPR(%) foi de 0,24% entre as seis replicatas testadas. Além disso, o método exibiu bons níveis de recuperação (de 98,24% a 100,74%). Consequentemente, considera-se que a validação atendeu a todos os requisitos farmacopêicos e o método pode ser considerado confiável, preciso, exato e seletivo para determinação de Nys e seus produtos de degradação.

A liquid chromatography method for evaluating the stability of Nystatin (Nys) in an ointment was developed and validated, since the traditional pharmacopeial microbiological methods are unable to indicate stability. The stress experiments showed that Nys was found to significantly degrade in alkaline and acidic conditions and also under oxidative stress. Lower levels of degradation were detected under heat and with the sample exposed to Xenon light. Resolutions higher than 2 for Nys and degradation products (DP) chromatographic peaks were achieved by using an Inerstil ODS-3 column, isocratic elution with methanol:water and UV detection at 305 nm. The system was found to be linear over a range of 102 to 310 IU mL-1 and proved precise, since the RSD(%) was 0.24% for the six replicates tested. The method also exhibited good levels of recovery (from 98.24% to 100.74%). Therefore, the validation fulfilled pharmacopeial requirements and the procedure was found to be reliable, precise, accurate and selective for determination of Nys and its degradation products.

An analytical method has been developed and validated for the determination of an association of ampicillins in a lyophilized powder for injection by HPLC. The advantage of chromatographic method other than the microbiological one is that, it is possible to monitor precisely, out-of-specification results in quality control processes and also during stability studies, in which an association of ampicillins is present. The proposed HPLC method was developed by using forced degraded samples, in order to reach a selective analysis of ampicillins when in the presence of their degradation products. It was possible to detect benzatine and through indirect calculation, to determine the ampicillin sodium in the drug sample. The method showed to be selective, accurate, precise, robust and linear (from 45.92 to 36.04 μg mL-1 of total ampicillin and from 14.53 to 43.28 μg mL-1 of benzatine). The accuracy determined from recovery test, gave results in the range of 99.41% of total ampicillin to 100.31% of benzatine. Hence, it can be concluded that the proposed HPLC method is applicable for ampicillins determination.