Meloxicam (MX) is a poorly water-soluble drug with severe gastrointestinal side effects. Topical hydrogel of hydroxypropyl guar (HPG) was formulated using a solid dispersion (SD) of MX with hydroxypropyl cellulose (LHPC) as an alternative to oral administration. The development of a solid dispersion with an adequate MX:LHPC ratio could increase the topical delivery of meloxicam. Solid dispersions showed high MX solubility values and were related to an increase in hydrophilicity. The drug/polymer and polymer/polymer interactions of solid dispersions within the HPG hydrogels were evaluated by SEM, DSC, FTIR, and viscosity studies. A porous structure was observed in the solid dispersion hydrogel MX:LHPC (1:2.5) and its higher viscosity was related to a high increase in hydrogen bonds among the -OH groups from LHPC and HPG with water molecules. In vitro drug release studies showed increases of 3.20 and 3.97-fold for hydrogels with MX:LHPC ratios of (1:1) and (1:2.5), respectively, at 2 h compared to hydrogel with pure MX. Finally, a fitting transition from zero to first-order model was observed for these hydrogels containing solid dispersions, while the n value of Korsmeyer-Peppas model indicated that release mechanism is governed by diffusion through an important relaxation of the polymer.
Keywords: hydrogels; hydroxypropyl guar; low-substituted hydroxypropyl cellulose; meloxicam; polymer/polymer interactions; solid dispersion.