Rheological evaluation of thermoreversible and mucoadhesive nasal gels of Zolmitriptan.

BACKGROUND AND OBJECTIVES Rheological evaluation of thermoreversible mucoadhesive nasal gel of zolmitriptan is done to determine the steady shear behaviour and gelation temperature. The thermoreversible mucoadhesive polymers are sucessesfully used to increase the contact time of the therapeutic compound in the nasal cavity as well as they cause enhancement in permeation of drug through the nasal mucosa. MATERIAL AND METHODS Pluronic (F127) and Pluronic (F 68) were used as thermoreversible polymers in combination with a mucoadhesive polymer obtained from natural resource Zolmiriptan anti migraine drug obtained from Cipla Ltd. Rheometer Brookfield R/S- CPS- PI having cone-and-plate geometry was used for steady shear behaviour study and the gelation temperature was determined by Brookfield R/S plus Rheometer (Brookfield viscometer Ltd, Harlow, Essex, UK) fitted with spindle and Eurotherm cone/plate geometry. RESULTS Steady shear behaviour study concludes as content of mucoadhesive polymer starts increasing subsequently the viscosity of the solution starts increasing in the same manner. Gelation temperature study suggests that as the mucoadhesive content was increased in formulation the gelation temperature of the formulation was decreased subsequently. So it was concluded from the study that gelation temperature of the formulation was influenced by the mucoadhesive content. Temperature increases the gelation time of the formulation. CONCLUSIONS Above studies indicate that even small difference in the composition of the thermoreversible mucoadhesives gel formulations may cause major change in the rheological behaviour. Although the gelation temperatures of all the three formulations L1, L2 and L3 were below the human nasal temperature, they show different responses to the varied shear rates at different temperatures below and above the temperature of nasal cavity.