Development of in situ gel for nasal delivery: design, optimization, in vitro and in vivo evaluation

Context: The mucoadhesive gel formulations are helpful to prolong the residence time at the nasal absorption site and thereby facilitate the uptake of drug. Sumatriptan succinate has oral bioavailability of 15% and undergoes hepatic metabolism, hence it is suitable for nasal administration. Objective: The objective of the investigation was to develop a mucoadhesive in situ gel to improve the bioavailability of the sumatriptan succinate. Materials and methods: Deacetylated gellan gum was used as gelling agent. In situ gel was formulated by ion activation mechanism in simulated nasal fluid. A 3 2 factorial design was found suitable to optimize batch. In vivo study was carried out in Spraugue-Dawley rats, and drug was estimated in plasma by UPLC-MS. Result: The optimized batch showed drug release of 98.57% within 5 h followed by Peppas model of drug release. Ex vivo studies on sheep nasal mucosa showed 93.33% within 5 h. In histopathological study, optimized batch was found to be safe and stable in accelerated stability study for three months. Optimized formulation, F7 has shown absolute bioavailability, which was found to be 164.70%. Drug targeting index for brain tissues was found to be 1.866. Discussion: Concentration of the gelling polymer was compromised for satisfactory gel strength and an acceptable viscosity. The release depended on viscosity of formulation. Drug targeting index indicates sumatriptan can reach to brain via olfactory pathway. Conclusion: In situ gel proved to be suitable for administration of sumatriptan succinate through nasal route. The ease of administration coupled with less frequent administration enhances patient compliance.