Oral insulin delivery by polymeric nanospheres

Carrier technology with biodegradable polymers offers an intelligent approach for drug delivery by entrapping the drug in a carrier particle such as nanospheres and nanoparticles which modulate the release and absorption characteristics. Among the biodegradable polymers, poly-epsilon-caprolactone (PCL) has been receiving increasing attention as matrix materials for controlled release drug formulations. Poly-epsilon-caprolactone and its derivatives, with a high permeability to many therapeutic drugs and lack of toxicity, are well suited for oral and controlled drug delivery. In our present work, the method for the efficient encapsulation of insulin in poly-epsilon-caprolactone nanospheres using a water-in-oil-in-water double emulsion solvent evaporation method was investigated and optimized. The nanospheres formed were characterized for percent yield, percent encapsulation efficiency, surface morphology, particle size, confocal microscopy, drug-polymer interaction, and in-vitro drug release profiles. The results obtained showed that nanospheres made with 1% polymer concentration gave better results than nanospheres with 0.5% or 1.5% polymer concentrations. A high percent yield of 99.3 +/- 0.13%, with a moderate entrapment efficiency of 51.43 +/-:0.04% was observed for nanospheres prepared with 1% PCL concentration. Differential scanning calorimetric studies showed no drug-polymer interactions. Scanning electron microscope scans showed the formation of smooth, spherical poly-epsilon-caprolactone nanospheres ensuring the successful formulation of PCL nanospheres encapsulating insulin, thus highlighting poly-epsilon-caprolactone as a potential biodegradable polymer for oral controlled drug delivery.