RESUMO
An improved HPLC method for the measurement of cimetidine and its major metabolite-cimetidine sulfoxide-is described. The mobile phase was a mixture of methanol-ammonium phosphate (20:80), and methanol was used to elute the drug avoiding the use of acetonitrile, a very hazardous solvent. A device has been developed to wash simultaneously ten or more cartridges and to reduce the time of analysis. With this procedure a plasma sample could be analyzed in less than 30 min. The limit of detection was 0.125 micrograms/ml for cimetidine and 1.00 micrograms/ml for cimetidine sulfoxide. The absolute recovery for cimetidine was 83% and 40% for its major metabolite; is greater than that reported by previous studies. The proposed method is rapid, accurate and precise, and it should be useful for clinical, bioavailability and pharmacokinetic studies of cimetidine.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cimetidina/sangue , Cromatografia Líquida de Alta Pressão/instrumentação , Cimetidina/análogos & derivados , Cimetidina/farmacocinética , Humanos , Metanol , SolventesAssuntos
Gravidez , Adulto , Humanos , Feminino , Metabolismo Energético , Troca Materno-Fetal , Glucagon , Hormônio do Crescimento , InsulinaRESUMO
In order to know the efficiency of the human pituitary hormone extraction method utilized in the laboratory, six batches of 100 pituitaries each, were collected in acetone. Its delipidization and the initial acid extraction (0.3 M KCl, pH 5.5) of the powder were performed in the presence of 0.1 per cent thioethanol and the extraction was completed with an alkaline solution (0.1 N NaOH + H2O, v/v, pH 10.5). Hields in weight of powder and protein concentration for each fraction were similar to those previously reported by Elrick. Characterization of fractions with disc-gel-electrophoresis demonstrated a reproducible pattern for GH, and some differences among the samples containing the glycoproteins. The hormonal activities determined by radioimmunoassay showed a low contamination of GH in the fractions rich in glycoproteins, but these latter were similarly distributed between the acid and the alkaline extracts. The glycoprotein fraction had an important activity of TSH. The hormonal content per pituitary was calculated from the addition of activities in both extracts and the last residue; GH = 3 mg (4.494 IU); FSH = 761 micrograms (13.410 IU); LH = 782 micrograms (46.920 IU); TSH = 2.939 mg (9.350 IU). It is concluded that the technique is useful since there was a low GH contamination in the glycoprotein fraction and the TSH yield was important.