title: Stability of non-aqueous topical tetracaine and clotrimazole solutions in polypropylene droptainer bottles.
abstract: Tetracaine topical solution may improve patient adherence with topical clotrimazole therapy for fungal otitis externa. The chemical stability of tetracaine 1% and combination clotrimazole 1% with tetracaine 1% topical solutions was determined using a stability-indicating high-performance liquid chromatography assay. Propylene glycol and polyethylene glycol 400 were used as anhydrous solvents. Standard curves for tetracaine and clotrimazole were linear with r2 > or = 0.999. Clotrimazole did not degrade in either propylene glycol or polyethylene glycol 400 throughout the 90-day study period. Tetracaine degraded significantly in propylene glycol but not in polyethylene glycol 400. A beyond-use date of 90 days is supported for tetracaine and the combination clotrimazole-tetracaine solution in polyethylene glycol 400. A beyond-use date of 60 days is supported for tetracaine and the combination clotrimazole-tetracaine in propylene glycol.
authors.affiliation: SIUE School of Pharmacy, Edwardsville, Il 62026, USA. tmcpher@siue.edu
authors.forename: Timothy B
authors.initials: TB
authors.lastname: McPherson
authors.affiliation: SIUE School of Pharmacy, Edwardsville, Il 62026, USA.
authors.forename: William L
authors.initials: WL
authors.lastname: Neumann
authors.affiliation: SIUE School of Pharmacy, Edwardsville, Il 62026, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: Kolling
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003022:Clotrimazole / Q000032:analysis / Q000737:chemistry*; D004349:Drug Packaging; D004355:Drug Stability; D011126:Polypropylenes; D012996:Solutions; D013748:Tetracaine / Q000032:analysis / Q000737:chemistry*
chemical_list: D011126:Polypropylenes; D012996:Solutions; D013748:Tetracaine; D003022:Clotrimazole