Rosso James Del, Harper Julie, Pillai Radhakrishnan, Moore Robert
Dermatology Residency Program, Director, Valley Hospital Medical Center, Las Vegas, Nevada;
J Clin Aesthet Dermatol. 2013 Feb;6(2):25-8.
Various formulations of tretinoin have been reported to be unstable after exposure to artificial light or sunlight. The observation that tretinoin is photolabile in the presence of light led to the recommendation that tretinoin be applied in the evening in order to avoid photodegradation, which could potentially reduce efficacy. More recently, the development of innovative vehicle formulations has led, in some cases, to a marked decrease in the photodegradation of tretinoin.
To compare the photostability of a micronized aqueous-based formulation of tretinoin gel 0.05% with tretinoin gel 0.025% following exposure to fluorescent and simulated solar light conditions in vitro.
Micronized tretinoin gel 0.05% and tretinoin gel 0.025% were exposed to fluorescent light over eight hours or simulated solar light up to 600mJ/cm(2) (equivalent to 30 minimal erythemal dose). Product samples were prepared and analyzed for tretinoin concentration using high-performance liquid chromatography. Additional duplicate samples were similarly prepared and analyzed after 2, 4, 6, and 8 hours.
There was an 11-percent degradation of tretinoin 0.05% formulated as the micronized gel compared to an 86-percent degradation of tretinoin 0.025% formulated as the conventional gel following eight hours of exposure to fluorescent light in vitro. The degradation of tretinoin 0.025% in the conventional gel was greater than 83 percent within two hours. In the second light exposure study, in vitro exposure to simulated solar light provided a gradual dose-response effect with tretinoin 0.05% formulated as the micronized tretinoin gel. The photodegradation of tretinoin 0.025% in the conventional gel was more immediate and of substantial magnitude (>85%) after exposures at all minimal erythemal dose levels.
Tretinoin 0.05% formulated as a micronized gel 0.05% showed minimal degradation when exposed to fluorescent light over eight hours. This same formulation exhibited a clear dose-response degradation pattern when exposed to simulated solar light. In contrast, tretinoin 0.025% formulated in a conventional gel exhibited marked photodegradation within the first two hours when exposed to both light conditions in vitro. This information adds to the body of evidence that supports the observation that certain vehicle formulations may reduce the potential for photodegradation of tretinoin.
据报道，维甲酸的各种制剂在暴露于人造光或阳光下后不稳定。维甲酸在光照下具有光不稳定的特性，这一观察结果导致建议在晚上使用维甲酸以避免光降解，因为光降解可能会降低疗效。最近，创新载体制剂的开发在某些情况下导致维甲酸光降解显著减少。
在体外荧光和模拟太阳光条件下，比较0.05%微粉化水基维甲酸凝胶与0.025%维甲酸凝胶的光稳定性。
将0.05%微粉化维甲酸凝胶和0.025%维甲酸凝胶暴露于荧光灯下8小时或模拟太阳光下直至600mJ/cm(2)（相当于30个最小红斑剂量）。制备产品样品并使用高效液相色谱法分析维甲酸浓度。在2、4、6和8小时后同样制备并分析额外的重复样品。
在体外暴露于荧光灯下8小时后，0.05%微粉化凝胶制剂的维甲酸降解了11%，而0.025%传统凝胶制剂的维甲酸降解了86%。传统凝胶中0.025%的维甲酸在两小时内降解超过83%。在第二项光照研究中，体外暴露于模拟太阳光下，0.05%微粉化维甲酸凝胶制剂的维甲酸呈现出逐渐的剂量反应效应。在所有最小红斑剂量水平暴露后，传统凝胶中0.025%的维甲酸光降解更迅速且程度较大（>85%）。
0.05%微粉化凝胶制剂的0.05%维甲酸在暴露于荧光灯下8小时时降解最小。该制剂在暴露于模拟太阳光下时呈现出明显的剂量反应降解模式。相比之下，0.025%传统凝胶制剂的维甲酸在体外暴露于两种光照条件下的前两小时内均表现出明显的光降解。这些信息进一步证明了某些载体制剂可能会降低维甲酸光降解的可能性。
