Purpose

Research has shown that co-administration of preparations containing HQ and azelaic acid (AZ) or vitamin C (vit C) may be more effective than HQ alone. The aim of this study was to evaluate the stability of HQ in the presence of AZ and vit C as active ingredients in the extemporaneous preparations prepared with different techniques.

Methods

Topical preparations containing HQ, vit C, and AZ were prepared using with aqueous and none-aqueous extemporaneous techniques. Some auxiliary antioxidants were used to stabilize vit C. Thermal stress condition was applied for stability evaluation. Digital images and HPLC analysis were performed to control the color changes and drug loss, respectively.

Results

Severe color changes happened in some formulations and dark brown color appeared. Color change was directly attributed to vit C loss but not related to HQ loss. HQ ointment with no antioxidant, showed no loss after stress incubation. AZ was partially able to increase the HQ and vit C stability in a combination formulation, but this stabilizing effect in binary formulations of HQ and AZ was not seen. SMB enhanced vit C stability. Aqueous preparation methods decreased the stability of formulations significantly. It can be recommended that HQ, vit C, and AZ be formulated in separate dosage forms.

Conclusion

Avoiding water incorporating or aqueous methods will enhance the stability of these formulations, as well. Intrinsic low stability of vit C in topical formulations may be enhanced using non-water incorporating or non-aqueous methods and utilizing SMB in suitable concentrations.

中文翻译：

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壬二酸和维生素C对即席外用制剂中氢醌稳定性的影响：基于证据的体外研究

目的

研究表明，与HQ和单独的HQ一起使用含有HQ和壬二酸（AZ）或维生素C（vit C）的制剂可能更有效。这项研究的目的是评估在使用不同技术制备的临时制剂中，AZ和vit C作为有效成分存在时HQ的稳定性。

方法

含有HQ，vit C和AZ的局部制剂是使用水性和非水性临时技术制备的。使用一些辅助抗氧化剂来稳定vitC。将热应力条件用于稳定性评估。进行数字图像和HPLC分析以分别控制颜色变化和药物损失。

结果

在某些配方中发生了严重的颜色变化，并出现了深褐色。颜色变化直接归因于vit C损失，但与HQ损失无关。不含抗氧化剂的HQ软膏，在应力孵育后无损失。AZ在组合制剂中能够部分提高HQ和vit C的稳定性，但是在HQ和AZ的二元制剂中却看不到这种稳定作用。SMB增强了vit C的稳定性。水性制备方法显着降低了制剂的稳定性。可以建议将HQ，vit C和AZ分别配制为剂型。

结论

避免掺水或水性方法也将增强这些制剂的稳定性。可以使用非水掺入或非水方法以及使用适当浓度的SMB来增强局部制剂中vit C的固有低稳定性。