Mathematical Modeling of the Release of Active Ingredients from a Contraceptive Patch: Ortho Evra(®) as a Case Study

Contraceptive patches have become a frequently used contraceptive method. We present a mathematical model that describes the serum concentration profiles of Norelgestromin (NGMN) and Ethinylestradiol (EE) released from the contraceptive patch Ortho Evra(®). We propose a simple one-compartment model based on pharmacokinetics data reported in previous studies. The model assumes a time-dependent release rate and a first order elimination rate for each of the active ingredients contained in the patch. The model was applied to noncompliance scenarios, such as total and partial detachment of the patch or prolonged use without patch replacement. The proposed model adequately describes the clinically observed evolution of NGMN and EE in serum. Predictions from the model were successfully validated using reported experimental data of serum concentrations of NGMN and EE. This simple model can be a valuable tool to predict pharmacokinetic profiles in diverse scenarios such us non-compliance situations. Alternatively, the model can be conveniently adapted to anticipate the effect of variations on patch characteristics such as differences in contact area, doses, materials, among others.