Parallel Artificial Membrane Permeability Assay (PAMPA)

The PAMPA was conducted using a previously reported method with some technical modifications.²⁴ Paired glass permeable diffusion cells with a PVDF membrane sandwiched between them were divided into supply and receiving chambers. A 4% (w/v) n-dodecane solution of egg yolk lecithin (artificial membrane solution, 500 μL) was added to the PVDF membrane and allowed to equilibrate for 30 min. Donor solutions (8 mL) and drug solutions (2 mL) of flavonoids (30 mg/mL) and flavonoids-APS (flavonoids: APS=1: 2) were added to the receiving and supply chambers, respectively. The samples were placed in thermostatic oscillator (37 °C, 300 r/min) and collected at 2, 4, 6, 8, 10,12 h from the receiving chamber for analysis using HPLC.

Calculation of effective permeability coefficient (Lg_Pe) and effective transmittance (P_eff) according to equation (5), (6) and (7).

V_d: volume of liquid added to the supply chamber; V_a: volume of liquid added to the receiving chamber; A=π-r²: effective area of the artificial membrane; t: incubation time (s); [drug]_a: drug concentration in receiving chamber at time t; [drug]_e: theoretical equilibrium concentration at time t; [drug]_d: drug concentration in supply chamber at time t.