An excerpt from an article "Preparation of Curcumin-Loaded Liposomes and Evaluation of Their Skin Permeation and Pharmacodynamics" is provided below:
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3.8. In Vitro Drug Release
A Franz diffusion cell was used to perform the release experiment. The dialysis tubing (molecular weight cutoff of 8,000 to 14,000) was mounted between the donor and the receptor compartments. The cell provided a diffusional area of 0.785 cm2, and the receptor compartment was 10 mL. The donor medium consisted of 0.2 mL of vehicle containing different types of liposomes. To maintain the sink condition, 0.5% tween-80 with 20% ethanol (v/v) in pH 6.5 PBS was used as receptor medium. The system was adjusted to ensure that the membrane surface was at 37 °C to mimic the in vivo conditions. The stirring rate was 400 rpm and the temperature was 37 °C. At different intervals (1, 2, 4, 8, 10, 12, 18, 24, 36, and 48 h), the receptor samples were removed and replaced with fresh receptor medium. The receptor samples were then analyzed for the drug content by HPLC. The cumulative amount of drug released was determined as a function of time, and the release rate was calculated.