Bioequivalência de duas formulações de oxalato de escitalopram comprimidos em voluntários sadios administradas em jejum / Bioequivalence of two tablets formulations of escitalopram oxalate in healthy volunteers under fasting conditions

O estudo foi conduzido para verificar a bioequivalência entre duas formulações de oxalato de escitalopram 10 mg, comprimidos. Foram 32 voluntários sadios de ambos os sexos que participaram no estudo randomizado, cruzado, dois períodos, com washout mínimo de dez dias. Um comprimido de cada formulação foi administrado após jejum noturno de dez horas. Após administração, amostras seriadas de sangue foram coletadas por 144 horas. As amostras de plasma foram analisadas para determinação do escitalopram por método validado de cromatografia líquida acoplada à detecção por espectrometria de massas (LC-MS-MS). Os parâmetros farmacocinéticos área sob a curva de concentração plasmática do tempo zero a última concentração medida (ASC0-t) e concentração máxima observada (Cmax) foram os principais critérios para verificação da bioequivalência entre as formulações. Área sob a curva de zero a infinito (ASC0-inf), tempo em que ocorre Cmax (Tmax) e meia-vida (t1/2) também foram determinados. Os intervalos de confiança (IC) de 90% obtidos por análise de variância (ANOVA) não mostraram diferenças significativas entre as duas formulações e caíram dentro dos limites pre-estabelecidos (96,91-106,79 para ASC0-t e 89,40-102,39 para Cmax). A bioequivalência entre as duas formulações foi demonstrada tanto em termos de taxa quanto de extensão da absorção.

Effect of Helicobacter pylori infection and acid blockade by lansoprazole on clarithromycin bioavailability

The effect of proton pump inhibitors and Helicobacter pylori infection on the bioavailability of antibiotics is poorly understood. We determined the effects of 5-day oral administration of 60 mg lansoprazole on the bioavailability of clarithromycin in individuals with and without H. pylori infection. Thirteen H. pylori-infected and 10 non-infected healthy volunteers were enrolled in a study with an open-randomized two-period crossover design and a 21-day washout period between phases. Plasma concentrations of clarithromycin in subjects with and without lansoprazole pre-treatment were measured by liquid chromatography coupled to a tandem mass spectrometer. Clarithromycin Cmax and AUC0-10 h were significantly reduced after lansoprazole administration. In addition, lansoprazole treatment of the H. pylori-positive group resulted in a statistically significant greater reduction in Cmax (40 vs 15 percent) and AUC0-10 h (30 vs 10 percent) compared to lansoprazole-treated H. pylori-negative subjects. Thus, treatment with lansoprazole for 5 days reduced bioavailability of clarithromycin, irrespective of H. pylori status. This reduction, however, was even more pronounced in H. pylori-infected individuals.

Plasma hydroxy-metronidazole/ metronidazole ratio in hepatitis C virus-induced liver disease

It has been suggested that the measurement of metronidazole clearance is a sensitive method for evaluating liver function. The aim of this study was to evaluate the usefulness of plasma hydroxy-metronidazole/metronidazole ratios as indicators of dynamic liver function to detect changes resulting from the various forms of chronic hepatitis C virus (HCV) infection. A total of 139 individuals were studied: 14 healthy volunteers, 22 healthy, asymptomatic, consecutive anti-HCV-positive HCV-RNA negative subjects, 81 patients with chronic hepatitis C (49 with moderate/severe chronic hepatitis and 34 with mild hepatitis), and 20 patients with cirrhosis of the liver. HCV status was determined by the polymerase chain reaction. Plasma concentrations of metronidazole and its hydroxy-metabolite were measured by reverse-phase high-performance liquid chromatography with ultraviolet detection in a blood sample collected 10 min after the end of a metronidazole infusion. Anti-HCV-positive HCV-RNA-negative individuals demonstrated a significantly reduced capacity to metabolize intravenously infused metronidazole compared to healthy individuals (0.0478 ± 0.0044 vs 0.0742 ± 0.0232). Liver cirrhosis patients also had a reduced plasma hydroxy-metronidazole/metronidazole ratio when compared to the other groups of anti-HCV-positive individuals (0.0300 ± 0.0032 vs 0.0438 ± 0.0027 (moderate/severe chronic hepatitis) vs 0.0455 ± 0.0026 (mild chronic hepatitis) and vs 0.0478 ± 0.0044 (anti-HCV-positive, HCV-RNA-negative individuals)). These results suggest an impairment of the metronidazole metabolizing system induced by HCV infection that lasts after viral clearance. In those patients with chronic hepatitis C, this impairment is paralleled by progression of the disease to liver cirrhosis.