Majority of newly discovered active substances are poorly soluble in water. Bioavailability of a poorly soluble drug with good permeability can be modified by increasing its dissolution rate and/or solubility. This can be achieved by incorporation of the drug in hydrophilic nanofibers. Increased specific surface area and better wetting improve the contact between solute and solvent. Amorphous forms of active ingredients usually exhibit higher solubility than their crystalline forms. The increase in contact surface and solubility improves dissolution rate according to the Noyes-Whitney equation.
Nanofibers were produced from ethanol solutions of poly(ethylene oxide), poloxamer 407 and ibuprofen. A precipitation inhibitor, namely Soluplus, hydroxypropyl methylcellulose (HPMC) 606 or HPMC 615, was added to the solutions. Nanofibers were prepared from the polymer solutions by electrospinning. The morphology of the produced nanofibers was studied by scanning electron microscopy. The analysis of ibuprofen solubility and release from the nanofibers were also performed.
Nanofibers were formed from all polymer solutions. Smooth nanofibers without any artifacts in morphology were produced from the formulation without precipitation inhibitor and from the formulation with the addition of HPMC 615. Addition of HPMC 606 resulted in beaded nanofibers and nanofibers with Soluplus were in the form of discontinuous cylinders that were interconnected with thin filaments. The average diameter and standard deviation of the diameter of different nanofiber formulations were determined. The release profiles of ibuprofen from different nanofiber formulations were similar. Ibuprofen was immediately released from all formulations as 90% of the active substance was released within the first 5 minutes. The results revealed that the addition of HPMC 606 does not stabilize the supersaturated state, while the addition of Soluplus effectively increases solubility or stabilizes the supersaturation (24 h or longer).
Based on the results of this study we can conclude that the addition of Soluplus facilitates efficient supersaturation or an increase in drug solubility. Further research should be focused on optimization of the nanofiber formulation with Soluplus to improve the reproducibility of the production process and to modify the composition to increase the drug loading and decrease the amount of Soluplus in the formulation.
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