Application of miscibility analysis and determination of Soluplus solubility map for development of carvedilol-loaded nanofibers
Electrospinning was used to produce carvedilol-loaded Soluplus polymer nanofibers using a systematic approach. Miscibility between drug and polymer was determined through calculation of the interaction parameter, χ, and the difference between the total solubility parameters, Δdt. A solubility map for Soluplus was obtained by examining different solvent systems, carrying out electrospinning, and characterizing the nanofibers formed. Miscibility studies showed that carvedilol and Soluplus can form a miscible system (χ = −2.3054; Δδt < 7.0 MPa1/2). Based on the Soluplus solubility map, acetone: chloroform (90:10; w/w) represents a suitable solvent system for electrospinning of carvedilol-loaded Soluplus nanofibers. Scanning electron microscopy of these nanofiber samples showed smooth surface morphology. The nanofibers had a regular cylindrical morphology. Beads appeared along the nanofibers more frequently in formulations with lower percentages of carvedilol. Differential scanning calorimetry showed no melting endothermic peak for carvedilol, which suggests its complete conversion from the crystalline to the amorphous form (at polymer: carvedilol 1:1). The infrared spectrum of the carvedilol-loaded Soluplus nanofibers showed no characteristic carvedilol peak at 3344.5 cm−1, which suggests interactions between carvedilol and Soluplus. Dissolution studies of these nanofibers showed improved pure carvedilol dissolution properties, with >85% of the carvedilol released in the first 15 min, versus 20% for pure carvedilol. The use of miscibility analysis and polymer solubility studies demonstrate great technological potential to tackle the challenge for inadequate dissolution of poorly water-soluble drugs.