A transdermal patch is designed to deliver Methadone. Before the drug is delivered across the skin, it diffuses through a rate-controlling membrane between the drug reservoir and skin. The surface area, thickness, diffusion coefficient, and partition coefficient K (Oil/Water) of the membrane is 10 cm2, 100m, 10-8 cm2 sec-1 and 10, respectively. Calculate the permeability coefficient of this drug through this membrane.

Continuing from the above, if the Methadone concentration in the patch reservoir is maintained at 16 mg/mL constantly during a 12-hour release period, how much drug is delivered? (Assuming sink condition, constant diffusion rate without lag time)