Synthesis and characterization of methoxypolyethyleneglycol and lauric acid grafted novel polyurethanes for controlled release of nifedipine

Abstract

Novel polyurethanes (PUs) grafted with methoxypolyethyleneglycol (mPEG) and lauric acid (LA) were synthesized by solution polymerization using dibutyl tin dilaurate as a catalyst, taking different molar ratios of LA-trimethylol propane (LA-TMP) with respect to mPEGtrimethylol propane (mPEG-TMP). The polymers obtained were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography to confirm, respectively, the PU formation and molecular weight. Moderate molecular-weight PUs were obtained, and nifedipine (NFD)-loaded microspheres were prepared by solvent evaporation method. The size of the microspheres as measured by laser light scattering technique ranged between 10 and 50 mm. An increase in the size of particles was observed with an increasing molar ratio of mPEG-TMP with respect to LA-TMP. The % encapsulation efficiency was found to vary between 65 and 92. The surface morphology of microspheres as studied by scanning electron microscopy revealed the spherical nature of the particles with wrinkles on their surfaces. Crystalline nature of the drug in the microspheres after loading was studied by X-ray diffraction technique. The release of NFD through the matrix microspheres was investigated in pH-7.4 phosphate buffer. An increase in release rate was observed with increasing molar ratio of mPEG-TMP with respect to LA-TMP.

Synthesis, characterization and evaluation of novel methoxypolyethyleneglycol‐ grafted‐ poly(ester‐urethane)s for controlled release of repaglinide

“…The estimated values of n in the formulations vary from0.5 to 0.65, indicating the Fickian type release trends. These trends are similar to those reported for other systems in the reported literature 6, 7, 19, 20…”

“…Polyurethanes were prepared by the method described earlier 7. Methoxy polyethylene glycol‐trimethylol propane (0.005 mol) and PCL (0.005 mol) were dissolved in DMF taken in a 100 mL round bottom flask fitted with addition funnel, nitrogen inlet and a guard tube.…”

“…Similarly, biodegradable polyurethanes (PUs) prepared from polyols are also biocompatible and biodegradable having excellent flexibility. In our previous research,6, 7 we have shown that PUs containing polyethylene glycol (PEG) exhibited good biocompatibility and biodegradability 8, 9. Polyesterurethanes (PEUs) have also been studied because of their flexibility and superior biocompatibility 10, 11.…”

“…As part of our continuing efforts6, 7 to develop novel types of biocompatible PUs, we now report on the synthesis of polycaprolactone diol‐based PEUs grafted with methoxy polyethylene glycol (mPEG) to investigate their use in controlled release (CR) of repaglinide, an antidiabetic drug, a fast and short‐acting meglitinide analog. The drug has low bioavailability (50%) and poor absorption in the upper intestinal tract15, 16 and hence, its consumption with the protective polymeric coating is necessary.…”