Predicting in vivo performance of fenofibrate amorphous solid dispersions using in vitro non-sink dissolution and dissolution permeation setup.

Amorphous solid dispersion (ASD) is emerging as a useful formulation strategy to increase the bioavailability of active pharmaceutical ingredients with poor solubility. In vitro dissolution testing under non-sink conditions has often been used to evaluate the ability of ASDs to generate and maintain supersaturation to predict the in vivo performance. However, such a single compartment dissolution setup can fail to predict the oral bioavailability, due to an interdependence between precipitation and permeation. Hence, the use of two compartment dissolution-permeation setups is emerging. In this study, three ASDs containing fenofibrate as model drug substance were developed using Soluplus®, and Hypromellose Acetate Succinate in two different grades (high and low), respectively. The aim was to compare the use of a small-scale in vitro non-sink dissolution setup and a small-scale in vitro dissolution-permeation setup to predict the in vivo oral exposure of the ASDs in rats. The maximum concentration (Cmax) and area under curve (AUC) obtained in the in vitro studies were used to predict the in vivo rank order of the formulations. The results showed that the two in vitro studies resulted in the same rank order based on both Cmax and AUC. Interestingly, Cmax resulted in a better in vitro/in vivo correlation than the in vitro AUC, and based on the in vitro Cmax, the in vivo rank order was predicted.

Bioavailability of seocalcitol II: development and characterisation of self-microemulsifying drug delivery systems (SMEDDS) for oral administration containing medium and long chain triglycerides.

By constructing ternary phase diagrams it was possible to identify two self-microemulsifying drug delivery systems (SMEDDS) containing either medium chain triglycerides (MC-SMEDDS) or long chain triglycerides (LC-SMEDDS), with the same ratio between lipid, surfactant and co-surfactant. The SMEDDS ended up having a composition of 25% lipid, 48% surfactant and 27% co-surfactant, MC-SMEDDS: viscoleo, cremophor RH40, akoline MCM and LC-SMEDDS: sesame oil, cremophor RH40, peceol. Upon dilution with water both SMEDDS resulted in clear to bluish transparent microemulsions with a narrow droplet size of 30nm. The industrial usefulness of the developed SMEDDS was evaluated with regard to bioavailability and chemical stability using the vitamin D analogue, seocalcitol, as model compound. The absorption and bioavailability of seocalcitol in rats were approximately 45% and 18%, respectively, from both the MC-SMEDDS and LC-SMEDDS indicating similar in vivo behavior of the two formulations, despite the difference in nature of lipid component. There was no improvement in bioavailability by the use of SMEDDS, compared to the bioavailability achieved from simple MCT and LCT solutions (22-24%) (Grove, M., Pedersen, G.P., Nielsen, J.L., Mullertz, A., 2005. Bioavailability of seocalcitol. I. Relating solubility in biorelevant media with oral bioavailability in rats-effect of medium and long chain triglycerides. J. Pharm. Sci. 94, 1830-1838.). After 3 months' storage at accelerated conditions (40 degrees C/75% RH), a decrease in concentration of seocalcitol of 10-11% was found in MC-SMEDDS and LC-SMEDDS compared with a degradation of less than 3% for the simple lipid solutions of MCT and LCT. In this study the simple lipid solutions seem to be a better choice compared with the developed SMEDDS due to a slightly higher bioavailability and a better chemical stability of seocalcitol.