Candida albicans is one of the most common species of Candida, which is an important cause of invasive candidiasis in clinic. Due to the frequently use of classical antifungal agents, there are amounts of drug resistant C. albicans being isolated, causing the significantly decreasing of the efficacy of some antifungal agents in clinical treatment. Besides, the use of some compounds in clinic has been limited because of their toxicities. In such a context, drug combination therapy shows great potential on antifungal because of the synergy of different drugs or therapeutic methods that could bring, which could improve the weaknesses of single drug.

Objective To prepare and characterize caspofungin acetate-loaded solid lipid nanoparticles using glycerol monostearate （CAS-SLNs）, and investigate the antifungal effect of potentiation on Candida albicans in vitro and in vivo. Methods A high performance liquid chromatography method was established for the determination of caspofungin acetate （CAS）. CAS-SLNs were prepared by the melt-emulsification method and characterized. The minimum inhibitory concentration （MIC） and the inhibitory effect on Candida albicans biofilm were determined. A systemic infection model of Candida albicans was established in mice, and the growth curve models for body weight and fungal load of kidneys of the animals were investigated after intravenous infection. Results The retention time of CAS was 6.8 min. The calibration curve showed good linearity, and the precision and stability met the requirements of the assay. Transmission electron microscopy revealed that CAS-SLNs were spherical, with a particle size of （135.97±1.73） nm. The Zeta potential was （19.33±0.37） mV, drug loading was （7.55±0.68）%, and encapsulation efficiency was （67.71±1.74）%. CAS-SLNs showed significant in vitro antifungal inhibition with a MIC of 9.78×10⁻⁴ g/ml, which was significantly better than CAS group and the physical mixture group of CAS and GMS, as well as the same biofilm inhibition was observed （P<0.001）. Pharmacodynamic studies demonstrated that CAS-SLNs maintained stable body weight gain compared to the control （P<0.01） and CAS groups in Candida albicans invasive infection model, and that CAS-SLNs significantly reduced renal fungal burden load relative to the CAS group （P<0.05）. In vivo study revealed that a stable body weight was maintained in CAS-SLNs group compared to the control group （P<0.01） in Candida albicans invasive infection model. CAS-SLNs also significantly reduced renal fungal load compared to the CAS group （P<0.05）. Conclusion CAS-SLNs significantly enhanced the antifungal effects of CAS in vitro and in vivo, which provided a valuable insight for the research of new formulation of CAS.