Development and evaluation of in situ nasal gel formulations of loratadine

The objective of the present work was to formulate and evaluate mucoadhesive in situ nasal gels of loratadine. This drug delivery system may overcome the first-pass metabolism and subsequently improve the bioavailability of the drug. A total of 16 formulations of in situ nasal gels were prepared using different polymeric ratios of hydroxypropyl methylcellulose (HPMC K-100) and xanthan gum. All formulations had a clear appearance in the sol form, with gelling temperature of the nasal gels ranging between 33.1 ± 0.43 and 34.8 ± 0.82 °C. The gelling time of all the formulations varied from 4.0 ± 0.21 to 11.3 ± 0.22 s; the drug content was >95%. The pH of the formulations ranged between 5.6 ± 0.004 and 6.0 ± 0.003, i.e. no mucosal irritation is expected as the pH was in the acceptable range. Mucoadhesive strength was adequate (3010.89 ± 1.21-6678.89 ± 0.45 dyne/cm2) to provide prolonged adhesion. In vitro drug release studies showed that the prepared formulations could release the drug for up to 10 h with all of them following Higuchi kinetics. The accelerated stability studies indicated that the gels were stable over the six months test period. The DSC and XRD analysis revealed that there was no drug-polymer interaction. From these findings it can be concluded that in situ nasal gels may be potential drug delivery systems for loratadine to overcome first-pass metabolism and thereby to improve the bioavailability.