Sodium lauryl sulfate

IMQ drug substance of GMP grade was purchased from Teva Pharmaceuticals Industries Ltd.—Teva API Division (Debrecen, Hungary). Aponorm 7 mL tubes, Aqua conservata DAC, Carbopol 974P, jojoba wax, polysorbate 80 and sodium hydroxide were purchased from Caesar & Loretz GmbH (Hillscheid, Germany). Zirconium oxide milling spheres of 1 mm diameter were purchased from Fritsch GmbH (Idar-Oberstein, Germany). Acetonitrile ≥ 99.9%, HiPerSolv CHROMANORM gradient grade and methanol ≥ 99.8%, HiPerSolv CHROMANORM gradient grade, WTW technical buffers TEP 2, STP-7 and STP-10 trace were purchased from VWR International GmbH (Darmstadt, Germany). Phosphoric acid LiChropur > 85%, sulfuric acid ≥ 98% LiChropur, Millex nylon syringe filters of 0.45 µm pore size and a diameter of 25 mm, triethylamine ≥ 99.5% LiChropur and IMQ USP Reference Standard were purchased from Sigma Aldrich Chemie GmbH (Taufkirchen, Germany). Ethanol Rotisolv HPLC gradient grade, heptane-1-sulphonic acid sodium salt, sodium lauryl sulfate ≥ 99% and Omnifix disposable 50 mL syringes with Luer-Lock fitting were purchased from Carl Roth GmbH (Karlsruhe, Germany). Inertsil ODS3-5 µm 250 mm × 4.6 mm and Zorbax RX-C8 150 mm × 4.6 mm 5 µm HPLC columns were purchased from MZ Analysentechnik GmbH (Mainz, Germany).

Micronized P4 was supplied by Euro OTC Pharma (particle size: x95 10 µm, Bönen, Germany). The EVA polymers used were EVA9 (Greenflex ML31, 9% VA, Versalis, Milan, Italy), EVA18 (ATEVA 1820, 18% VA, Celanese, Irving, TX, USA), EVA28 (Greenflex ML60, 28% VA, Versalis, Milan, Italy) and EVA40 (ELVAX 40L_03, 40% VA, DuPont de Nemours, GmbH, Neu-Isenburg, Germany). For the preparation of the dissolution medium, Milli-Q water (in-house preparation, MicroPure TKA), glacial acetic acid (Merck KGaA, Darmstadt, Germany), sodium lauryl sulfate (SLS) and sodium acetate trihydrate (both Carl Roth GmbH + Co. KG, Karlsruhe, Germany) were used. For the mobile phase, ethanol of HPLC grade (Sigma Aldrich, Vienna, Austria) and MilliQ water were applied.

Polycaprolacton (PCL, MW 14.000) and Nile red (NR, MW 318.37) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Acetone, sodium lauryl sulfate (SDS) (99%—MW 288.38) and tween 80 (T80) were purchased from Carl Roth (Karlsruhe, Germany). Lutensol AT50 (LAT50) was a donation from BASF (Ludwigshafen, Germany). Cethyltrimethylammoniumbromide (CTAB) (99%—MW 364.46) was purchased from Merck (Darmstadt, Germany). Deionized water was used throughout the experiments. All chemicals were used as received.