The USP paddles apparatus (Biobase Biodustry, Jinan, Shandong China) was used to study in vitro drug release from the developed TOFs. Briefly, an in vitro release study was performed in 0.1 N HCl (pH, 1.2) for 2 h and in phosphate buffer (pH, 6.8) for 24 h. Approximately 500 mL of 0.1 N HCl (pH, 1.2)/PBS (pH, 6.8) was poured in dissolution vessels. The film size was cut per unit dose and placed in a steel wire mesh. Then mesh was tied with paddles. The temperature was kept at 37 ± 0.5 °C and stirring speed was adjusted at 100 rpm. The samples (5 mL) were drawn at predetermined time intervals (0, 1, 2, 3, 4, 5, 6, 8 and 24 h) and fresh dissolution medium was added every time a sample was taken to maintain the sink conditions. The drug release was analyzed using Shimadzu-HPLC-LC-10AD (Shimadzu Corporation, Kyoto, Japan) at 257 nm [29 (link)]. The mobile phase was composed of an acetonitrile:methanol:ammonium acetate buffer (20:30:50) and was equipped with a C-18 column (5 mm, 25,034.0 mm; Agilent). The flow rate of 1 mL/min and column temperature of 40 °C were maintained throughout analysis.
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