The drug permeation studies were performed using a Franz diffusion cell (PermeGear Inc., Hellertown, PA, USA) with a 3.14 cm2 diffusion area and a receptor volume of 10 mL. Strat-M membranes (Merck Millipore, Darmstadt, Germany) were used as skin-mimic artificial membranes. Prior to the diffusion experiments, the membranes were soaked in PBS (pH 7.4), at room temperature, for 12 h. After that period, the membranes were placed between the donor and the receptor compartments, and the latter was filled with PBS. The system was maintained under constant magnetic stirring (500 rpm), and the temperature was controlled at 37 °C by a circulating water bath.
In each experiment, a cylindrical API-loaded hydrogel sample (1.7 cm diameter; 0.3–0.5 cm thickness) was applied to the membrane. To minimize evaporation, the donor compartment and sampling port were occluded with parafilm. Periodically, a 400 µL sample was collected from the receptor compartment, and the same volume was replaced with a fresh and preheated receptor solution. Ibuprofen, caffeine, and diclofenac concentrations in the withdrawn solution were determined by high-performance liquid chromatography (HPLC) (Dionex Summit, Sunnyvale, CA, USA) using an Eclipse C18 column 4.6 × 250 mm (Agilent, Santa Clara, CA, USA) equipped with an amperometric detector. The analysis was performed at 25 °C, with acetonitrile-dipotassium hydrogen phosphate (65:35 v/v) as eluent, at a flow rate of 0.7 mL/min. The salicylic acid concentration in the withdrawn solution was determined by HPLC, using a Luna C18 column 4.6 × 250 mm (Phenomenex, Torrance, CA, USA). The mobile phase was a mixture of acetonitrile (ACN) and 0.1% of trifluoroacetic acid (TFA) used with the concentration of ACN varying from 12.5 to 100 to 12.5% in 0.1% TFA with the flow rate of 0.5 mL/min. The analysis was performed at 25 °C.
In each experiment, a cylindrical API-loaded hydrogel sample (1.7 cm diameter; 0.3–0.5 cm thickness) was applied to the membrane. To minimize evaporation, the donor compartment and sampling port were occluded with parafilm. Periodically, a 400 µL sample was collected from the receptor compartment, and the same volume was replaced with a fresh and preheated receptor solution. Ibuprofen, caffeine, and diclofenac concentrations in the withdrawn solution were determined by high-performance liquid chromatography (HPLC) (Dionex Summit, Sunnyvale, CA, USA) using an Eclipse C18 column 4.6 × 250 mm (Agilent, Santa Clara, CA, USA) equipped with an amperometric detector. The analysis was performed at 25 °C, with acetonitrile-dipotassium hydrogen phosphate (65:35 v/v) as eluent, at a flow rate of 0.7 mL/min. The salicylic acid concentration in the withdrawn solution was determined by HPLC, using a Luna C18 column 4.6 × 250 mm (Phenomenex, Torrance, CA, USA). The mobile phase was a mixture of acetonitrile (ACN) and 0.1% of trifluoroacetic acid (TFA) used with the concentration of ACN varying from 12.5 to 100 to 12.5% in 0.1% TFA with the flow rate of 0.5 mL/min. The analysis was performed at 25 °C.
Free full text: Click here
