RESUMO
Is well known that food can affect the bioavailability of several drugs, its impact is major for those drugs that have to act near of drug absorption. Documentation about alterations of ranitidine bioavailability by effect of food is poor. The purpose of this work was to evaluate the effect of food over the bioavailability of ranitidine. Twenty healthy Mexican volunteers were included for the study. The study was made in two stages, in the first one the volunteers had 12 hour fast and took a 300 mg of oral dose of ranitidine (without food, WOF) and blood samples were drawn. Two weeks later, the volunteers took a normal diet just before ranitidine intake (with food, WF). The area under the curve (AUC) was 30% greater in WOF, Cmax was 921.5 ng/ml (WF) vs. 1685.2 (WOF), and t1/2 was 2.70 +/- 1.38 (WF) h vs 3.66 +/- 1.34 (WOF). The AUC, Cmax and t1/2 were statistically different. It is evident that there are differences in the drug disposition due to the presence of food, then, it is possible that the efficacy of ranitidine as inhibitor of gastric secretion being limited by food.
Assuntos
Antiulcerosos/farmacocinética , Interações Alimento-Droga , Ranitidina/farmacocinética , Adolescente , Adulto , Antiulcerosos/sangue , Área Sob a Curva , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Feminino , Meia-Vida , Humanos , Masculino , México , Pessoa de Meia-Idade , Ranitidina/sangueRESUMO
BACKGROUND: Anemia is the most prevalent hematological problem in elderly persons, affecting 14% of the males and 6% of the females of the population over 60 years of age in Mexico City. OBJECTIVE: To determine the effect produced by the prolonged administration of ferrous fumarate in elderly persons with iron deficiency. METHOD: In a population of 178 subjects, aged between 65 to 100 years, iron deficiency was diagnosed in 51 (28.6%), who had serum iron concentrations below 80 micrograms/dL for men and 60 micrograms/dL for women, but only 21 patients (11.8%), accepted to participated in the study. The response to a 6 months oral administration of ferrous fumarate were studied with a daily oral dose of 5 mg/kg of elemental iron. The patients were classified in 3 groups according to the abnormal parameters of iron metabolism (group 1 = 10.9% anemia, group 2 = 28.0% and group 3 = 63.0% anemia). RESULTS: The efficacy of treatment was evaluated by quantification of the changes occurred in serum iron concentrations, hemoglobin, ferritin and transferrin saturation index, at 0, 30, 90 and 180 days of treatment. This study showed that the treatment of oral ferrous fumarate in elderly patients with iron deficiency, produces a quantifiable improvement in measures of iron parameters within 6 months. CONCLUSIONS: The results of this study suggest the usefulness of prolonged treatment with ferrous fumarate in elderly patients with iron deficiency, to avoid therapeutic failure as a consequence of non-compliance as is common in elderly patients.