During industrial manufacturing, formulation, and storage, the tendency towards isomerization of astaxanthin (AXT) may affect its bioavailability. Potential additives like potassium carbonate, potassium acetate, dipotassium hydrogen orthophosphate, potassium hydroxide, and cesium carbonate were mixed to solutions of AXT and chloroform in order to increase the stability of all-trans AXT while present in solution. The additives should not cause any damage to neither the dissolved nor the crystalline substance. Concentration changes in the course of time were measured and monitored by HPLC and a photometer. The additives exerted different effects on the dissolved AXT, either enhancing or weakening the isomerization processes and/or decomposition. Potassium carbonate and dipotassium hydrogen orthophosphate insufficiently affected the preservation of the all-trans AXT structure. In contrast, potassium acetate, potassium hydroxide, and cesium carbonate led to satisfying results and can be recommended as additives.