Poly(ethylene oxide) Gel Based Dimexide Ointment

Abstract

Dimexide (dimethyl sulfoxide, DMSO), approved for medical applications since 1971, is used for the treatment of contusions, strained muscles, edemas of various etiology, lymphostasis, burns, phlegmons, hemarthrosis, acute and chronic thrombophlebitis, erysepilatous inflammations, eczemas, diffuse streptoderma, and other disorders. The main medicinal form of dimexide administration are applications and compresses using 30 – 70% aqueous DMSO solutions (most frequently, 50% solution) [1 – 3]. However, this form is rather inconvenient since a patient has to prepare the solution at home. Another disadvantage is a pronounced specific odor sometimes complicating use of DMSO solutions. Despite the broad range of indications for administration and the wide experience gained on using DMSO in practice, optimum medicinal forms of dimexide have yet to be developed. Creation of an ointment containing 50% DMSO is a complicated task because a base with such a high content of this liquid is difficult to densify. Another problem is related to the fact that DMSO is a strong penetrant facilitating absorption of the base components through the skin. This property of DMSO excludes using hydrocarbon bases for preparation of DMSO ointments because the absorption of hydrocarbons and other lipophilic ointment-forming components detrimentally affects the gas exchange and water metabolism in the skin. Therefore, dimexide ointments should be developed using hydrophilic water-soluble polymer-based components. A promising modern medicinal form of dimexide is offered by analgesic and antiinflammatory gel preparations [4]. Such gels are prepared based on gelatin, poly(vinyl pyrrolidone) (PVP), or starch and additionally contain taurine. We have prepared a series of dimexide gels according to recommendations [4]. It was found that some characteristics of the preparations (appearance, colloidal stability, rheological properties) do not meet the pharmacopoeial requirements. The gels appear as viscous liquids, exhibit strong characteristic odor, and seem “greasy” to the touch. The ointments exhibit separation into layers on standing and cannot be strictly classified as gels due to unsatisfactory elastic-plastic behavior. In contrast, a gel prepared on carbopol base [5] possess valuable organoleptic properties, an attractive appearance, and good spreading capacity owing to the pronounced elastic-plastic properties. This gel is stable on storage, but still has a pronounced odor and was “greasy” to the touch. The purpose of this study was to create a ready-to-use medicinal form – a dimexide ointment – with a DMSO content in the range from 30.0 to 70.0% using bases not containing hydrocarbons (paraffin, vaseline, vaseline oil) and free of the aforementioned disadvantages (odor and “greasy” feel). The work was performed in cooperation with specialists of the Pyatigorsk Pharmaceutical Plant.