Menorest: technical development and pharmacokinetic profile.

Transdermal application of oestradiol enables the use of lower doses than with the oral drug and avoids first-pass metabolism in the liver. First-generation transdermal delivery systems were of reservoir design. Menorest is one of a new generation of patches, in which oestradiol is dispersed in a micronized suspension throughout the adhesive matrix. This design results in a very thin patch with good cosmetic acceptability. Pharmacokinetic studies indicate that Menorest allows transdermal release of oestradiol at a constant and reproducible rate at doses from 25-100 micrograms/day. There is a linear relationship between the dose of oestradiol administered (which is determined by the surface area of the patch) and the plasma concentration of oestradiol. In contrast to the standard reference reservoir patch, Estraderm, Menorest maintains plasma oestradiol concentrations at or above the target level of 40 pg/ml throughout the 84-h dosing interval.