Formulation and Efficacy Studies of New Topical Anesthetic Creams
Abstract Local anesthetics (lidocaine or tetracaine) spontaneously melted at 25°C when mixed with thymol and aqueous isopropyl alcohol solution (IPA) at proper ratios and formed novel two-phase melt systems (TMS). The TMS consisted of a homogeneous oil phase containing primarily a local anesthetic a...
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Veröffentlicht in: | Drug development and industrial pharmacy 2003-01, Vol.29 (5), p.505-512 |
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Sprache: | eng |
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Zusammenfassung: | Abstract
Local anesthetics (lidocaine or tetracaine) spontaneously melted at 25°C when mixed with thymol and aqueous isopropyl alcohol solution (IPA) at proper ratios and formed novel two-phase melt systems (TMS). The TMS consisted of a homogeneous oil phase containing primarily a local anesthetic agent (lidocaine or tetracaine) and thymol, and a homogeneous aqueous phase containing primarily IPA and pH 9.2 buffer. The relationship between melting of the solid components and system composition was determined from the phase diagram obtained by a titration method. A select TMS of a local anesthetic agent (lidocaine or tetracaine) was directly emulsified to prepare an O W cream and tested for the anesthetic efficacy on intact human skin. While both lidocaine (6%) and tetracaine (4%) creams were highly effective for dermal anesthesia with a similar onset time, the tetracaine cream exhibited a significantly longer duration of action than the lidocaine cream. An accelerated stability study indicated that lidocaine was significantly more stable than tetracaine in the creams. |
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ISSN: | 0363-9045 1520-5762 |
DOI: | 10.1081/DDC-120018639 |