Soluplus

The drug loading (DL%) and encapsulation efficiency (EE%) were determined by membrane filtration method [49 (link)]. TQ-SSM were filtered with a 0.20 µm filter membrane. The non-encapsulated TQ was retained on the membrane, while 20 µL of the filtrate was disrupted with 980 µL of MeOH.
The amount of TQ encapsulated and loaded into polymeric micelles was quantified by HPLC: the mobile phase consisted of (A) formic acid/water pH 3.2 and (B) acetonitrile. The flow rate was set at 0.8 mL/min. The gradient profile was: 0.10–25 min 10–90% B, 25–27 min 9% B, 27–30 min 10% B. For the calibration curve, different concentrations ranging from 0.002 µg/µL to 0.99 µg/µL were used. The linear correlation coefficient was >0.999. The DL% and EE% were calculated by equations (1) and (2), respectively:
$\mathrm{DL}\%=\frac{\mathrm{Weight}\mathrm{of}\mathrm{TQ}\mathrm{in}\mathrm{nanomicelles}}{\mathrm{Weight}\mathrm{of}\mathrm{fed}+\mathrm{Weight}\mathrm{of}\mathrm{the}\mathrm{excipients}}\times 100$
$\mathrm{EE}\%=\frac{\mathrm{Weight}\mathrm{of}\mathrm{TQ}\mathrm{in}\mathrm{nanomicelles}}{\mathrm{Weight}\mathrm{of}\mathrm{TQ}\mathrm{fed}}\times 100$

AGN was dried in the oven at 55°C for 24 h and cooled at room temperature. The AGN sample was then stored at 4°C until milling. Coarse and ultrafine powder formulations were acquired by the reported milling methods with slight modifications [11 (link)]. AGN samples were milled into coarse powder by a pin crusher (JIC-P10-2; Myungsung Machine, Seoul, Korea) equipped with a 30-mesh sieve. The milled powder was fractionated using a sieve shaker (CG-213, Ro-Top, Chunggye Industrial Mfg. Co., Seoul, Korea) equipped with a series of sieves (Φ 20 cm). The powder was passed through 300-μm mesh size sieves, and unpassed particles were grinded again with the pin crusher. Those powders were then stored at 25°C before ultrafine milling. The coarse powders were pulverized and classified by a low temperature turbo mill (HKP-05; Korea Energy Technology Co., Ltd., Seoul, Korea). The powders were pulverized after passing an impeller with high rotation speed, and the first, second, and third stator classifier system was used to classify particles using centrifugal and drag forces. For ultrafine powder processing, the rotor speed was set as 10,500 rpm, and the temperature of mill chamber was kept at -18°C. The ultrafine AGN powder obtained was stored in a desiccator before its use.
Particle sizes of coarse and ultrafine AGN (F1 and F2) were measured by a particle size analyzer (Mastersizer 2000; Malvern Instruments Ltd., Worcestershire, UK), by using the laser diffraction technique. Particle size was measured at 25°C with a scattering angle of 90°. The average particle size indicates the mean value of 9 measurements for every sample.
AGN-based oral formulations were prepared in this investigation according to the experimental conditions and composition ratios shown in Table 1. For solid formulations, ultrafine AGN powder and water (4:1, w/w) was extruded by different shears using an STS-25HS twin-screw extruder (Hankook E.M. Ltd., Pyoung-Taek, Korea) equipped with a round-shaped die (1 mm in diameter), according to the presented temperatures (Table 2). Three different (low, middle, and high) shear stresses were generated by the different screw arrangements. Each shear stress (low, middle, and high) was represented by measuring specific mechanical energy (SME) [23 ]. The feeding amount of sample was 28 g. Water (20% of total input weight) was added at 1.0 mL/min speed to the extruder. The speed of screw was 150 rpm and the diameter of die was 1.0 mm, respectively. In Soluplus-included formulations, ultrafine AGN powder was mixed with the determined ratios of Soluplus and then extruded with high shear stress. Prepared AGN-based formulations were dried in the oven at 40°C.

The effect of co-surfactant Soluplus^® was tested by preparing a series of Pluronic^®/Soluplus^®@VES-GEM mixed micelles with a varying Pluronic^® molar ratio and decreasing Pluronic^® F68 and Pluronic^® F127 concentration to compensate for the addition of the co-surfactant. Briefly, Pluronic F68^®/Soluplus^®@VES-GEM mixed micelles (0.375/0.375/1 and 0.75/0.375/1) and Pluronic F127^®/Soluplus^®@VES-GEM mixed micelles (0.375/0.375/1 and 0.75/0.375/1) were prepared as explained above, but with co-dissolving polymeric surfactants at the desired concentration in the ethanolic VES-GEM solution, and stirred for 3 h at RT before dropwise addition to PBS diluted in water (50:50 v/v, 15 mL) [66 (link)].