Background An alternative liquid sevoflurane for vascular ulcers has recently been reported in the literature. Innovative topical application of this halogenated anaesthetic for management of analgesia appears to be successful. The selection of dimethyl sulfoxide (DMSO) as a vehicle for sevoflurane responds to both pharmaceutical and pharmacological needs: it is a polar solvent and chemically compatible with sevoflurane over a wide range of concentrations. Additionally, some studies suggest it might possess some analgesic, hydroxyl free radical scavenger, healing and antimicrobial properties after topical application, enhancing the activity of sevoflurane.

Purpose To evaluate the stability of sevoflurane dilution in DMSO.

Material and methods Sevoflurane dilutions 1:2 and 1:50 in DMSO were prepared and stored at different temperatures (23°C, 6°C and -10°C) for 21 days. The presence of sevoflurane and its degradation products in the samples was determined by gas chromatography (GC) with flame ionisation detector, and by ¹H, ¹⁹F, and proton decoupled ¹⁹F nuclear magnetic resonance (19F NMR).

Results Over 21 days, the clear and colourless solution remained. 19F NMR in the same signals were observed in all samples, these signals corresponding to the unchanged chemical structure of sevoflurane and DMSO. Meanwhile, in the GC analysis, no occurrence of any additional peak was shown at each storage temperature. For both analytical techniques, no breakdown products were detected in any of the samples.

Conclusion This study shows that different concentrations of sevoflurane in DMSO retain their chemical composition after exposure to different temperatures for a period of at least 21 days. These findings represent an important step in the pharmaceutical formulation of topical sevoflurane solutions.

References and/or Acknowledgements To Ignacio Rodríguez García, Department of Chemistry and Physics. University of Almería

No conflict of interest.