ESPE Abstracts

Background: We have previously shown that estradiol (E₂) matrix patches for adults could be cut in smaller pieces to administer low doses for pubertal induction in girls with hypogonadism. With a slow increase of the patch size during a few years, serum E₂ levels in normal girls undergoing puberty can be closely mimicked.

Objective and hypotheses: To evaluate storage conditions once the patch has been cut.

Method: Evorel^® 25 μg/24 h patches, containing 1.55 mg E₂ (Janssen-Cilag Pharmaceutica N.V.) were used. The outer edge on the patch were cut off and discarded. Two equal 1/7 pieces were cut, following the dotted marks on its cover. The cut pieces were stored together with the remaining patch in its foil-lined sachets, either i) in a plastic bag in the fridge ii) in a plastic bag in room temperature or iii) just in room temperature. Storage for 0, 1, 2, 3, 4, and 5 days were compared. E₂ concentrations were determined in the entire patch. The patch pieces were put in a solution of n-hexan+ethylacetat and put on slow shaking for 1 h. The samples were thereafter serially diluted. After totally evaporated, reconstitution was made using zero calibrator. E₂ concentrations were determined by RIA with lower limit of detection 9 pmol/l and total coefficient of variation (CV) 9% for 250 pmol/l and above.

Results: In average, 1/7 pieces of a 25 μg patch contained 190 μg E₂ which is 86% of the expected concentration. No difference was seen either in time of storage, the way the patches were stored or how many edges that were cut. Total CV was 3%.

Conclusion: In vitro, the patches contained the expected drug amount E₂ and it was evenly distributed on the surface. After cutting the patches, E₂ concentrations were stable for at least 5 days storage.