Millex hv syringe driven filter unit

The mass ratio of dry powder collected after spray-drying to the initial solid compositions before drying was calculated to determine the percentage yield of each sample. For drug content calculation, a precisely scaled amount of the spray-dried samples was dissolved in 10 mL of distilled 50% methanol and stirred at 400 rpm by a magnetic stirrer (AREC. X heating magnetic stirrer, Velp Scientifica Srl, Italy) at room temperature for 24 h. Then, samples were filtered by filtration disks (0.45 µm pore size, Millex-HV syringe-driven filter unit, Millipore Corporation, Bedford, MA, USA) and quantified spectrophotometrically at λ 258 nm by UV (ATI-Unicam UV/VIS Spectrophotometer, Cambridge, UK). The percentage of ketoprofen content was determined as a ratio of calculated to theoretical drug content.

A modified paddle method (Hanson SR8 Plus, Teledyne Hanson Research, Chatsworth, CA, USA) from European Pharmacopeia was applied to study the release of KETO [102 ]. A 100 mL vessels’ volume instead of 1000 mL was used with smaller paddle size. A simulated lung fluid (SLF), which was composed of NaCl, NaHCO₃, CaCl₂, NaH₂PO₄, H₂SO₄, and glycine (pH = 7.4), was prepared [103 ]. Vessels were filled with 50 mL of SLF, and temperature was set to 37 °C. These parameters were designed based on the human airways’ circumstances [104 (link),105 (link)]. The raw drug and samples equivalent to 5 mg of KETO (based on drug content analysis) were dispersed in the medium. We decided the pulmonary dose of KETO as 10% of its oral dose [60 (link)]. The rotation of paddles was adjusted to 50 rpm, and the duration of the study was 120 min. A total of 2 mL of each sample was withdrawn and replenished after 5, 10, 15, 30, 60, and 120 min. Samples were filtered (filtration disks with 0.45 µm pore size, Millex-HV syringe-driven filter unit, Millipore Corporation, Bedford, MA, USA), and then quantified spectrophotometrically at λ 258 nm (UV/VIS ATI-UNICAM UV/VIS Spectrophotometer, Cambridge, UK). Measurements were carried out in triplicate.