Effect of pentoxifylline on the pharmacokinetics of rosiglitazone in Wistar rats.

The aim of this study was to investigate the effect of pentoxifylline (PTX), an antiplatelet agent, on the pharmacokinetics of rosiglitazone (RSG) in rats. Pharmacokinetic parameters of RSG were determined in rats after oral administration (3 mg/kg/day) in the presence and absence of PTX (10 mg/kg) 3 times daily. Compared to control animals, rats pretreated with PTX for 7 days had a decrease in RSG peak plasma concentration (Cmax) of 19% with no change in the values of the area under the concentration-time curve (AUC). Alternatively, rats coadministered single-dose PTX did not show any differences from control with regard to RSG Cmax and AUC parameters. The time to peak concentration (tmax) of RSG was significantly increased in rats pretreated with PTX under both single- and multiple-dose conditions, whereas the elimination half-life (t1/2) of RSG was increased only with multiple-dose PTX pretreatment. In conclusion, the presence of PTX was found to cause a slight decrease in the oral exposure of RSG in rats. Concurrent use of PTX with RSG therefore needs to be appropriately evaluated for proper dose adjustments in humans.

First-principles investigation of strain effects on the energy gaps in silicon nanoclusters.

First-principles density functional calculations were performed to study strain effects on the energy gaps in silicon nanoclusters with diameter ranging from 0.6 to 2 nm. Hydrostatic and non-hydrostatic strains have been found to affect the energy gaps differently. For the same strain energy density, non-hydrostatic strain leads to a significantly larger change in the energy gap of silicon clusters compared to that of the hydrostatic strain case. In contrast, hydrostatic and non-hydrostatic strain effects on the energy gaps of bulk Si or larger size Si quantum dots are comparable. Non-hydrostatic strains break the tetrahedral bonding symmetry in silicon, resulting in significant variation in the energy gaps due to the splitting of the degenerate orbitals in the clusters. Our results suggest that the combination of energy gaps and strains permits the engineering of photoluminescence in silicon nanoclusters and offers the possibility of designing novel optical devices and chemical sensors.