Abstract
Dimethyl sulfoxide is a well-known and widely used dermal penetration enhancer. Its incorporation in transdermal patches would be highly desirable; however, due to its volatility this is extremely challenging. Here, we report on the feasibility of a dimethyl sulfoxide (DMSO) containing transdermal system containing estradiol as a model compound. Transdermal patches were prepared from duro-tak® 387-2510 containing various DMSO concentrations at different drying temperatures. The resulting patches were analyzed for DMSO content, estradiol and DMSO release, estradiol and DMSO permeation through excised porcine skin, and recrystallization during stability testing. Drying conditions in the range of 35° to 40° allowed a complete polymer solvents removal while retaining significant amounts of DMSO (≤10 mg/patch). Estradiol skin permeation increased 4-fold (Jss = 4.12 µg/cm−2·h−1) compared to DMSO-negative control (Jss = 1.1 ± 0.2 µg/cm−2·h−1). As additional benefit, estradiol recrystallization was inhibited by DMSO at even lowest solvent concentrations. Storage stability was limited to 6 months at 25 °C with a surprising discrepancy between DMSO content (significantly lower) and flux (not significantly different). Although the technical feasibility range is relatively narrow, such DMSO-containing matrix-type patches are able to significantly enhance drug permeation through the skin while ameliorating the product stability against recrystallization.
Highlights
The skin is the largest organ of the body and it functions as an effective barrier, the skin represents an attractive option for the administration of drugs for their systemic availability
dimethyl sulfoxide (DMSO) was supplied by VWR (Darmstadt, Germany). ß-Estradiol (E2), 1,3-dimethyl2-imidazolidinone, and γ-Cyclodextrin were obtained by TCI Chemicals (Eschborn, Germany)
Integrating DMSO in transdermal patches exhibited several benefits compared to conventional patch formulations
Summary
The skin is the largest organ of the body and it functions as an effective barrier, the skin represents an attractive option for the administration of drugs for their systemic availability. Drug delivery across the skin is an essential alternative over, e.g., the oral drug administration, because it offers a number of advantages over other routes of delivery, including avoiding first-pass metabolism, reducing peak plasma concentrations, the potential of delivering at controlled rates, and increasing patient compliance [1]. Since transdermal administration is not suitable for all drugs or therapeutic indications, it requires a detailed study of the physicochemical and biological properties of the drugs in question. A successful drug molecule for passive transdermal delivery is preferentially nonionic, lipophilic, and effective at low doses, and has a low molecular weight (
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