Liquiritigenin is a chiral flavonoid present in licorice and other medicinal plants. The nature of its biological fate with respect to the individual enantiomers has not been examined. In this study, we characterize, for the first time, the stereoselective PHARMACOKINETICs of liquiritigenin. Liquiritigenin was intravenously (20 mg/kg) and orally (50 mg/kg) administered to male Sprague-Dawley rats (n=4 per route of administration). Concentrations in serum and urine were characterized via stereospecific reversed-phase, isocratic HPLC method with UV detection. Serum concentrations were quantified but rapidly fell to undetectable levels. Sliquiritigenin showed a short half-life (0.25-0.54 h), while a better estimation of half-life (26-77 h) and other PHARMACOKINETIC parameters was observed using urinary data. The flavonoid is predominantly excreted via non-renal routes (fe values of 0.16-3.46 %), and undergoes rapid and extensive phase II metabolism. Chiral differences in the chemical structure of the compound result in some PHARMACOKINETIC differences. Serum concentrations rapidly declined, making modeling difficult. S-liquiritigenin showed an increased urinary half-life.

This study was designed to assess PHARMACOKINETIC parameters and pattern of pharmacodynamic effects (heart rate and blood pressure) of 100 mg Atenolol tablets in comparison with those of 100 mg Tenormin tablets as reference. A double blind cross over study was carried out among 12 healthy male subjects. A HPLC system using RP-C18 column and fluorescence detector was used to assess Atenolol in plasma. Heart r ate and blood p pressure was measured by the t rained clinic staff. Peak levels were observed about 2.97h for Atenolol and 3.73h for Tenormin after oral dosing. Cmax values for both formulations were about 0.49 µg/ml. AUC0-24was about 4.89 µg.h/ml for the test and 5.31 µg.h/ml for the reference group. Atenolol given orally caused a significant reduction in heart rate, systolic and diastolic blood pressure after administration of two formulations (P<0.05). It is concluded that two formulations are not significantly different in terms of pharmacodynamic and PHARMACOKINETIC parameters which were studied.  

Background and the purpose of the study: Encapsulation of human insulin in lipid vesicular systems such as niosomes was sought as a route to protect this protein against proteolytic enzymes and to improve its oral bioavailability. The purpose of this study was to assess the effect of insulin encapsulation in niosomes on oral bioavailability in diabetic rats.Methods: Recombinant human insulin was entrapped in multilamellar niosomes composed of polyoxyethylene alkyl ether surfactants (Brij 52 and Brij 92) or sorbitan monostearate (Span 60) and cholesterol. The amount of insulin released in simulated intestinal fluid (SIF) and simulated gastric fluid (SGF) were measured at 37oC. The protection of entrapped insulin against pepsin, α-chymotrypsin and trypsin were evaluated in comparison with free insulin solution. Diabetes was induced by IP injection of streptozotocin (65 mg/kg) in male wistar rats and effects of orally administered niosomes and subcutaneously injected insulin on hypoglycemia and elevation of insulin levels in serum were compared.Results and conclusion: The extent and rate of insulin release from Brij 92 and Span 60 vesicles were lower than that of Brij 52 niosomes (P<0.05). Vesicles protected insulin in comparison with free insulin solution against proteolytic enzymes (P<0.05) significantly. Animals treated with oral niosome-encapsulated insulin (100 IU/kg) showed decreased levels of blood glucose and elevated serum insulin, which in the case of Brij 92 niosomes, hypoglycemic effect was significant (P<0.05).Niosomes were also stable in solubilizing bile salt solutions and could effectively prolong the release of insulin in both SGF and SIF. Results of this study showed that niosomes may be utilized as oral carriers of insulin, however, to increase bioavailability of insulin, further studies on the protease inhibitor co-encapsulation in niosomal formulations might be helpful.