A pharmacokinetic study comparing a low-dose estrogen contraceptive transdermal system with an oral contraceptive tablet in healthy adult females

Background This study evaluated pharmacokinetics (PK) of a once-weekly low-dose estrogen contraceptive transdermal system (TDS) and a once-daily combined oral contraceptive (COC) in healthy women.Research design and methods In this Phase 1 study, 24 healthy women aged 18–35 years were randomized to crossover sequence of three consecutive 168–hour applications of the norelgestromin ([NGMN] drug load 4.86 mg/ethinyl estradiol ([EE] drug load 0.264 mg) TDS to the abdomen (Treatment A) or buttock (Treatment B), followed by once-daily COC (drug load 0.18 mg norgestimate/0.025 mg EE) for 7 days (Treatment C). Plasma NGMN and EE concentrations were assessed using standard PK parameters; application-site irritation, residual patch analysis, and safety were also evaluated.Results Variability in NGMN and EE exposure was lower for Treatments A and B versus Treatment C (AUCτ,ss: NGMN, 38.4% and 31.7% versus 47.0%; EE, 49.3% and 35.4% versus 51.2%) with comparable or lower Cp,ss(max) variability. EE Cp,ss(max) and normalized exposure were lower with the NGMN/EE TDS. No serious adverse events occurred. Residual patch analysis indicated delivery of ~200 µg/day NGMN and 19 µg/day EE.Conclusions The NGMN/EE TDS demonstrated lower PK variability, EE peak concentrations and normalized EE exposure than the COC. No new safety signals were reported.