Supersaturated Self-Nanoemulsifying Drug Delivery Systems (Super-SNEDDS) Enhance the Bioavailability of the Poorly Water-Soluble Drug Simvastatin in Dogs

This study investigates the potential of supersaturated self-nanoemulsifying drug delivery systems (super-SNEDDS) to improve the bioavailability of poorly water-soluble drugs compared to conventional SNEDDS. Conventional SNEDDS contained simvastatin (SIM) at 75% of the equilibrium solubility (S(eq)). Super-SNEDDS containing SIM at 150 and 200% of S(eq) were produced by subjecting the SNEDDS preconcentrates to a heating and cooling cycle. The super-SNEDDS were physically stable over 10 months. During in vitro lipolysis of SNEDDS and super-SNEDDS the SIM concentration in the aqueous phase increased for the first 30 min almost proportional to the drug loads and amounts of preconcentrate employed. The 200% drug-loaded super-SNEDDS generated an amorphous SIM precipitate at the end of in vitro lipolysis. In vivo, the relative bioavailability of SIM from super-SEDDDS increased significantly to 180 ± 53.3% (p = 0.014) compared to the dosing of two capsules of (dose equivalent) 75% drug-loaded SNEDDS. A significant increase in the terminal half-life of elimination was observed for super-SNEDDS (2.3 ± 0.6 h) compared to conventional SNEDDS (1.4 ± 0.3 h) as well as a decreased area under the curve ratio of the SIM metabolite simvastatin acid to the parent compound (0.57 ± 0.20 and 0.90 ± 0.3), possibly due to a combination of saturation effects on presystemic metabolising enzymes and prolonged absorption along the small intestine. In summary, this study demonstrated that super-SNEDDS are a viable formulation option to enhance the bioavailability of poorly water-soluble drugs such as simvastatin while reducing the pill burden by an increased drug load of SNEDDS

Development of Physiologically Based Pharmacokinetic/Pharmacodynamic Model for Indomethacin Disposition in Pregnancy

Findings of a recent clinical study showed indomethacin has lower plasma levels and higher steady-state apparent clearance in pregnant subjects when compared to those in non-pregnant subjects reported in separate studies. Thus, in the current work we developed a pregnancy physiological based pharmacokinetic/pharmacodynamic (PBPK/PD) model for indomethacin to explain the differences in indomethacin pharmacokinetics between pregnancy and non-pregnancy. A whole-body PBPK model with key pregnancy-related physiological changes was developed to characterize indomethacin PK in pregnant women and compare these parameters to those in non-pregnant subjects. Data related to maternal physiological and biological changes were obtained from literature and incorporated into the structural PBPK model that describes non-pregnant PK data. Changes in indomethacin area under the curve (AUC), maximum concentration (Cmax) and average steady-state concentration (Cave) in pregnant women were predicted. Model-simulated PK profiles were in agreement with observed data. The predicted mean ratio (non-pregnant:second trimester (T2)) of indomethacin Cave was 1.6 compared to the observed value of 1.59. In addition, the predicted steady-state apparent clearance (CL/Fss) ratio was almost similar to the observed value (0.46 vs. 0.42). Sensitivity analysis suggested changes in CYP2C9 activity, and to a lesser extent UGT2B7, as the primary factor contributing to differences in indomethacin disposition between pregnancy and non-pregnancy. The developed PBPK model which integrates prior physiological knowledge, in vitro and in vivo data, allowed the successful prediction of indomethacin disposition during T2. Our PBPK/PD model suggested a higher indomethacin dosing requirement during pregnancy