Cytotoxicity of Ciprofloxacin and Steroids in Mouse Tympanic Membrane Fibroblasts

Abstract

Objective Ciprofloxacin, commonly given as eardrops, has been shown to adversely affect tympanic membrane fibroblasts. Dexamethasone potentiates this effect. A newly available eardrop contains ciprofloxacin and fluocinolone, a more potent steroid. We evaluated the cytotoxic effects of this preparation on mouse tympanic membrane fibroblasts. Study Design Prospective, in vitro. Setting Academic laboratory. Subjects and Methods In experiment 1, fibroblasts were exposed to 1:10 dilutions of commercially available 0.3% ofloxacin, 0.3% ciprofloxacin, 0.3% ciprofloxacin + 0.1% dexamethasone, 0.3% ciprofloxacin + 0.025% fluocinolone, or dilute hydrochloric acid (control), twice within 24 hours. In experiment 2, cells were also treated with the dilutions of the pure form of dexamethasone 0.1% or fluocinolone 0.025%, alone and in combination with ofloxacin or ciprofloxacin. Cells were exposed to the solutions for 2 hours each time and were placed back in growth media after the treatments. Cells were observed with phase-contrast microscope until the cytotoxicity assay was performed. Results Survival of fibroblasts treated with ofloxacin was not different from the control. Fibroblasts treated with ciprofloxacin, ciprofloxacin + dexamethasone, or ciprofloxacin + fluocinolone had much lower survival (all P < .0001). Cells treated with ciprofloxacin + fluocinolone had lower survival than ciprofloxacin ( P < .0001) and ciprofloxacin + dexamethasone ( P = .0001). Steroids alone also decreased fibroblast survival compared to control ( P < .0001). The combination of dexamethasone or fluocinolone with ciprofloxacin, but not ofloxacin, further decreased fibroblast survival ( P < .0001). Phase-contrast images mirrored the cytotoxicity findings. Conclusion Tympanic membrane fibroblast cytotoxicity of ciprofloxacin is potentiated by corticosteroids. This effect may be deleterious when treating a healing perforation but beneficial when treating granulation tissue on the tympanic membrane.

Cytotoxicity of Ear Drop Excipients in Human and Mouse Tympanic Membrane Fibroblasts

“…As PSB is a component of the commercial cipro + fluocinolone preparation, this likely explains the much higher mouse TM fibroblast cytotoxicity we observed with commercial cipro + fluocinolone than we saw with the same formulation made in our laboratory (ie, without PSB). 5 PSB showed much less cytotoxicity with human TM fibroblasts. We have subsequently assessed commercial cipro + fluocinolone for cytotoxicity in the human TM fibroblast cell line and confirmed the more modest influence of PSB (C.O.D., unpublished observations).…”

“…The cytotoxicity of these “excipients” may have contributed to the toxicity that has previously been attributed to quinolones and steroids in commercial ear drops. 1-6…”

“…As the active ingredients and concentrations were identical, we postulated that the adverse effect was due in part to an excipient in the commercial cipro 1 fluocinolone product. 5 The commercial preparation contains significant levels of the surfactant, polysorbate 80, and trace amounts of povidone, both of which have been reported to be cytotoxic. [7][8][9][10] Prior studies have suggested that the excipients in both commercial ophthalmic preparations 11,12 and commercial otic preparations, such as propylene glycol, may contribute to target organ damage.…”

The Effects of Steroids on Survival of Mouse and Human Tympanic Membrane Fibroblasts

“…Our studies on the adverse effects of quinolones on the collagen-rich TM have raised concerns of potentiation by the addition of steroids. 1,2,5,6 However, the potential adverse TM effects by exposure to steroids were raised far earlier. [8][9][10]24 Here, we demonstrated that hydrocortisone, dexamethasone, and fluocinolone decreased survival of mouse and human TM fibroblasts.…”

“…1,[4][5][6] Both dexamethasone and fluocinolone decreased mouse TM fibroblast survival compared to control, and the combination of dexamethasone or fluocinolone with ciprofloxacin further decreased fibroblast survival. 5 The addition of dexamethasone to ofloxacin or ciprofloxacin also delayed rat TM healing relative to ofloxacin or ciprofloxacin alone. 6 Impaired TM healing following exposure to topical steroids has previously been reported in animals with both dexamethasone and hydrocortisone [8][9][10] and in humans with dexamethasone.…”