Espectrofotometria derivada: uma contribuição prática para o desenvolvimento de métodos / A contribution to the derivative spectrophotometry method

A espectrofotometria derivada (ED) tem sido utilizada como uma importante ferramenta no controle de qualidade de medicamentos para a determinação simultânea de fármacos em sistemas multicomponentes. Esta técnica oferece uma alternativa para melhorar a sensibilidade e a seletividade na análise de misturas e está acessível à maioria dos laboratórios. O procedimento é simples, rápido e não necessita extração prévia da amostra. Este trabalho tem como objetivo fornecer subsídios para o desenvolvimento de método por espectrofotometria derivada, utilizando a técnica do ponto de anulação, visando utilizá-la como um método alternativo no controle de qualidade de fármacos associados e, em especial, nos estudos de dissolução. Muitos subsídios foram retirados da literatura, outros de experiências vivenciadas no laboratório durante o desenvolvimento do método por ED aplicado na análise de dois inibidores da protease do vírus da imunodeficiência humana. Várias ordens de derivadas, diferentes valores de lambda delta e diferentes velocidades de varredura foram avaliados.

Derivative spectrophotometry has been successfully used as a quality control tool in pharmaceutical analysis for the simultaneous determination of drugs in multicomponent formulations. This technique, accessible to most laboratories, offers an alternative means of enhancing the sensitivity and specificity in mixture analysis. The procedure is simple, rapid and does not require any preliminary separations or treatment of the samples. The aim of this study is to provide pointers for the development of methods of analysis by derivative spectrophotometry (DS), using the zerocrossing technique, and to encourage professionals and researchers to use DS as an alternative method for quality control of drug combinations, especially in the study of dissolution. Much information, extracted from the literature, has been assembled here, together with the laboratory experience gained while developing a DS method to analyze a combination of two human immunodeficiency virus protease inhibitors. Various orders of derivatives, values of delta lambda and scan speeds were tested.

Effect of addition of rituximab to salvage chemotherapy on outcome of patients with diffuse large B-cell lymphoma relapsing after an autologous stem-cell transplantation.

BACKGROUND: We have investigated if rituximab-based salvage regimens improve response rates and survival of patients with diffuse large B-cell lymphoma (DLBCL) relapsing after an autologous stem-cell transplantation (ASCT). PATIENTS AND METHODS: We have retrospectively analyzed 82 patients with DLBCL who received salvage therapy for relapse or progression after ASCT. Patients were divided into two groups, according to whether rituximab-based salvage regimens were given (n = 42, 'R-' group) or not (n = 40, 'R+' group) after ASCT. RESULTS: Patients in the R+ group had better complete remission (CR) (55% versus 21.4%, P = 0.006) and overall response (OR) (75% versus 40.4%, P = 0.001) rates, and better 3-year event-free survival (EFS) (37% versus 9%, P = 0.002) and overall survival (OS) (50% versus 20%, P = 0.005) than patients in the R- group. Patients retreated with rituximab had better CR (42.9% versus 21.4%, P = 0.032) and OR (66.7% versus 40.4%, P = 0.019) rates, and better OS (36.2% versus 20% at 3 years, P = 0.05) and EFS (36.2% versus 9% at 3 years, P = 0.05) than patients who received chemotherapy alone at relapse after ASCT. CONCLUSIONS: The addition of rituximab to salvage chemotherapy improves response rates and EFS in patients with relapsed DLBCL after ASCT. These patients may benefit from rituximab retreatment, although larger prospective studies are needed to confirm these results.