Formulation and Characterization of Daridorexant Floating Raft-Forming In Situ Gel for Gastroretentive Drug Delivery

Abstract

This study developed and evaluated a daridorexant floating raft-forming in situ gel for prolonged gastric retention and controlled nighttime drug delivery. Six formulations, DRG1–DRG6, were prepared using sodium alginate, calcium carbonate, sodium bicarbonate and Tween 80. The formulations were assessed for appearance, pH, viscosity, gelation time, raft strength, floating lag time, total floating duration, drug content, in vitro release, release kinetics and accelerated stability. Increasing sodium alginate and calcium carbonate concentrations improved gelation, raft strength and buoyancy while slowing drug release. DRG4 showed the most balanced performance, with pH 7.26 ± 0.03, viscosity 428.2 ± 19.4 mPa·s, gelation time 31 ± 2 s, raft strength 8.12 ± 0.48 g, floating lag time 28 ± 2 s, drug content 99.18 ± 1.16% and 94.18% release at 12 h. Release followed the Korsmeyer-Peppas model, indicating anomalous transport. DRG4 remained stable for three months under accelerated conditions without meaningful changes in performance parameters.