Pet Allergy & Dermatology Specialists, Allentown, Pennsylvania, USA.
Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
Vet Dermatol. 2024 Dec;35(6):704-715. doi: 10.1111/vde.13289. Epub 2024 Aug 19.
Silver sulfadiazine (SSD) is commonly formulated into otic preparations to treat otitis externa, although evidence of stability and antimicrobial efficacy with long-term storage is lacking.
To evaluate the effect of storage time on chemical stability and in vitro antimicrobial activity of SSD diluted in sterile water, including two 1% suspensions using SSD pharmaceutical-grade powder stored at room temperature (RT) in plastic or sterile glass bottles, and a 1:9 dilution using prescription SSD 1% cream stored at RT in a sterile glass bottle.
Liquid chromatography-tandem mass spectrometry (LC-MS/MS) assessed chemical stability. Trimethoprim/sulfamethoxazole-susceptible and trimethoprim/sulfamethoxazole-resistant strains of Staphylococcus pseudintermedius (SP), meticillin-resistant (MR) SP, S. schleiferi (SS), MRSS, Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli evaluated by 24 h time-kill analysis assessed in vitro antimicrobial efficacy. Each assessment was performed at zero, one, three and six months of storage.
LC-MS/MS showed no significant change in concentration over time for any suspension. When adjusted for time and species/strain, all SSD suspensions showed significant reductions in colony forming units (cfu)/mL at 24 h (p < 0.001). Including all suspensions, a bactericidal effect (minimum 3-log cfu/mL reduction at 24 h) occurred against 94% of total isolates, with failure against 33 of 552 isolates (6%). Bactericidal failure was more likely with the cream-based suspension (p < 0.05) and at six months (p < 0.01).
Powder-based and cream-based SSD/sterile water suspensions showed no significant change in concentration and demonstrated in vitro antimicrobial activity for six months. Bactericidal failure was more likely with the cream-based suspension and after six months of storage.
磺胺嘧啶银（SSD）常用于配制耳部制剂治疗外耳炎，尽管缺乏长期储存时的稳定性和抗菌功效的证据。
评估储存时间对 SSD 稀释于无菌水中的化学稳定性和体外抗菌活性的影响，包括两种使用 SSD 药用级粉末在室温（RT）下储存于塑料或无菌玻璃瓶中的 1%混悬剂，以及一种使用处方 SSD 1%乳膏在 RT 下储存于无菌玻璃瓶中的 1:9 稀释液。
液相色谱-串联质谱（LC-MS/MS）评估化学稳定性。采用 24 小时时间杀菌分析评估对甲氧西林敏感和耐药的中间葡萄球菌（SP）、耐甲氧西林的 SP（MRSP）、施氏葡萄球菌（SS）、耐甲氧西林的 SS（MRSS）、铜绿假单胞菌、奇异变形杆菌和大肠埃希菌的体外抗菌功效。每种评估均在零、一、三、六个月储存时进行。
LC-MS/MS 显示任何混悬剂的浓度随时间均无显著变化。当按时间和种/株进行调整时，所有 SSD 混悬剂在 24 小时时的菌落形成单位（cfu）/mL 均显著减少（p<0.001）。包括所有混悬剂，94%的总分离株对杀菌作用有反应（24 小时时至少减少 3 个对数 cfu/mL），552 株分离株中有 33 株（6%）失败。乳膏基混悬剂（p<0.05）和六个月时（p<0.01）发生杀菌失败的可能性更大。
基于粉末和乳膏的 SSD/无菌水混悬剂在六个月的储存期内浓度无显著变化，并显示出体外抗菌活性。乳膏基混悬剂和储存六个月后更有可能发生杀菌失败。
