Background The use of topical 2% aqueous eosin in the treatment of periostomal dermatitis with varying degrees of injury has recently been reported in the literature, but the presence of periostomal ulcer is difficult to cure with eosin. Allantoin has several beneficial effects as an active agent, promoting cell proliferation and wound healing. No physical or chemical stability study has been conducted to date in order to check the conditions and maximum storage time in which a mixture of eosin and allantoin could be safely kept.
Purpose To evaluate the stability of an eosin and allantoin mixture used in the treatment of periostomal ulcer patients by proton nuclear magnetic resonance (1H-NMR) spectroscopy.
Material and methods Aqueous eosin and allantoin were prepared to a final concentration of 2%. The mixtures were packed and stored in opaque glass bottles. Bottles were stored at 23°C for a total period of 14 days in a chamber with a digitally controlled temperature. The physical parameters monitored were clearness, colour and the formation of particulate matter. The pH variation was also determined. Chemical stability was determined by 1H-NMR spectroscopy. The NMR spectra of the reference compounds were acquired. Spectroscopic signals were interpreted and assigned to the chemical structure of eosin and allantoin, and then consecutive spectra were acquired on days 1 and 14. Signals obtained in these experiments were compared with those of the reference compound. All spectra were acquired using a Bruker Avance DRX 300 MHz spectrometer equipped with a 5 mm single axis z-gradient quattro nucleus probe (Bruker Biospin GmbH, Rheinstetten, Germany).
Results On day 1, the clear and colourless solution remained, a precipitate was formed and the pH varied from 7.2 to 6.5. 1H-NMR signals identical to those of the reference compounds were observed. However, some byproduct signals were observed in the next check on day 2.
Conclusion An aqueous 2% eosin and allantoin mixture preserved in opaque glass bottles under the described conditions was not stable for a period of time greater than 1 day. This observations makes this mixture unsuitable as a therapeutic alternative for the treatment of periostomal ulcer patients.
References and/or acknowledgements University of Almería.
No conflict of interest
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