Understanding biorelevant drug release from a novel thermoplastic capsule by considering microstructural formulation changes during hydration.
OBJECTIVE
To study the biorelevant drug release from novel starch-based polyvinyl alcohol capsules (S-PVA-C). The effect of the shell material is studied by considering microstructural formulation changes during hydration.


METHODS
Two different self-emulsifying systems containing either fenofibrate or probucol were filled in S-PVA-C, as well as capsules of gelatin (SGC) and starch (VegaGels®). Release analysis employed a BioDis® apparatus, while disintegration was studied by texture analysis. For microstructural analysis we used small angle x-ray scattering (SAXS).


RESULTS
S-PVA-C opened only partially in biorelevant media compared to completely opened SGC and VegaGels®. In case of the fenofibrate formulation, this opening mechanism caused only a short lag time, while the probucol formulation in S-PVA-C resulted in a sustained release. The latter formulation demonstrated much higher viscosity upon hydration compared to the fenofibrate system. Such a rheological effect on drug release was barely noted for SGC or VegaGels® and SAXS revealed differences in the hydrated microstructure.


CONCLUSIONS
Even though S-PVA-C are highly attractive for encapsulation of rather hydrophilic formulations, some care is needed regarding an immediate release form. The type of formulation hydration must be considered for adequate selection of the capsule material.
Institute of Pharma Technology, University of Applied Sciences and Arts Northwestern Switzerland,, Gründenstr. 40, 4132, Muttenz, Switzerland.
Zdravka
Z
Misic
Raphael
R
Urbani
Thomas
T
Pfohl
Katharina
K
Muffler
Georg
G
Sydow
Martin
M
Kuentz
D002214:Capsules / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry; D011345:Fenofibrate / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D010316:Particle Size; D011142:Polyvinyl Alcohol / Q000737:chemistry; D011341:Probucol / Q000737:chemistry; D053838:Scattering, Small Angle; D013213:Starch / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods
D002214:Capsules; D003692:Delayed-Action Preparations; D004655:Emulsions; D005780:Gelatin; D011142:Polyvinyl Alcohol; D013213:Starch; D011341:Probucol; D011345:Fenofibrate