Bioavailability of estradiol from two matrix transdermal delivery systems:Menorest (R) and Climara (R)

Objectives: To compare two estradiol transdermal matrix systems with regard to bioavailability, pharmacokinetics and tolerability. Methods: A single c entre, open, randomized, comparative cross-over study in 20 healthy postmen opausal women. Menorest(R) with 3 or 4 days of suggested use and Climara(R) with 7 days of suggested use (both 50 mu g/24 h) were compared at steady s tate. Two 14-day treatment periods were separated by a 4 week washout. Plas ma levels of estradiol were monitored during the second week of each treatm ent. Tolerability was assessed by open questions and inspection of the appl ication site. Results: There were no differences between the two treatments With regards to AUC, C-max, C-min, C-average or fluctuations of plasma est radiol. T-max was significantly shorter for Menorest(R) than Climara(R). C- max and C-min were significantly higher for the second Menorest(R) patch du ring the monitoring period compared to the first. Ah local reactions were m ild and there were three cases of erythema with Menorest(R) and a total of 21 skin reactions in 15 subjects with Climara. Systemic tolerability was si milar between treatments with eight estrogen-related adverse events in eigh t subjects (period pains, uterine bleeding, mastodynia, headache and vagina l discharge) with Menorest(R) and 13 events in ten subjects with Climara(R) . Conclusions: The bioavailability of estradiol from the two matrix transde rmal delivery systems Menorest(R) and Climara(R) was similar, but the produ cts were not bioequivalent because T-max was significantly shorter for Meno rest(R) than for Climara(R) Tolerability of treatment was good for both pat ches but with a higher number of local reactions and estrogen related adver se events for Climara(R). (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.