Sustained Release of Poorly Water-Soluble Drug from Hydrophilic Polymeric Film Sandwiched Between Hydrophobic Layers
This proof-of-concept study explores the feasibility of using a drug-loaded hydrophilic polymeric layer sandwiched between two hydrophobic layers for improving film drug load while achieving sustained release of poorly water-soluble drug. Such films having total thickness in range ~ 146–250 μm were prepared by slurry-based casting using hydrophilic hydroxypropyl methylcellulose (HPMC) as matrix layer containing fenofibrate (FNB) as the model drug, encased between two very thin rate-limiting layers of 10 μm each of hydrophobic poly-ɛ-caprolactone (PCL). Film precursor slurry consisted of HPMC with plasticizer and water along with micronized FNB powders, which were dry-coated with hydrophilic silica. Characterization techniques demonstrated the presence of homogeneously dispersed crystalline FNB in films. The films are very thin and hence two-dimensional; hence, average drug load per unit area in range ~ 5 to ~ 9 mg/cm2 could be achieved by altering the thickness of the drug matrix layer. Drug amount and drug content uniformity were measured through assay of ten circular samples ~ 0.712 cm2 in area punched out using a circular-shaped punch tool. Drug release rate was investigated using USP IV flow-through cell and surface dissolution imaging system. Thinner films followed Fickian diffusion, and thicker films followed non-Fickian anomalous diffusion. Overall, the application of middle layer thickness could be used as a tool to manipulate drug load without the need for altering its formulation or precursor preparation by changing its thickness, hence achieving relatively high drug loading yet having sustained release of drug.
KEY WORDSsustained release sandwich films poorly water-soluble drugs micronized fenofibrate powder release kinetics
The authors appreciate useful discussions and comments from Prof. Ecevit Bilgili and Dr. Scott Krull on earlier versions of this paper and also thanks to Mr. Benchafia Mostafa for his assistance with ATR-FTIR spectroscopy analysis.
The study was supported by financial grant from the National Science Foundation (NSF) through grant nos. EEC-0540855 and IIP-1312125.
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