Construction, Exosyndrome And Skin Targeting Study Of Liranaftate Solid Lipid Nanoparticles-based Gel

OBJECTIVESLiranaftate (LN) is topical used for superficial mycosis therapy and the therapeutic effect is correlated to the absorption by skin. At present, skin absorption of LN in market cream is merely been 0.01%. To increase uptake rates and targeting of LN by skin, we constructed LN-losded solid lipid nanoparticles (SLN) and its gel by emulsification-solvent diffusion method. The research methods and experimental basis of this carrier systerm could improve topical application of drugs for superficial mycosis.METHODS AND RESULTS1. Construction of LN-SLNA HPLC method was established for quantization of LN-SLN, the range of LN concentration of 1-40μg/mL was found in a good linear relation with peak areas. Intra-and inter-day precision were both less than 3%. The average recovery rate was (100.04±3.11)%. The micro-column centrifugal method can be used for the determination of entrapment efficiency of LN-SLN, which showed good reproducibility and high recovery.Emulsification-solvent diffusion method was better than microemul-sion method, pellicle-ultraphonic dispersion method in preparing LN-SLN, which was evaluated with entrapment efficiency (EE), mean diameter and stability. Single factor study and orthogonal test were carried out to study prescription and technology process respectively, the optimal preparation flowsheet was as follows:300 mg soybean phospholipid (Epikuron 200),90 mg glycerin monostearate (GMS), 10mg cholesterol (CHO) and 5 mg LN were dissolved in 5 mL ethanol and 5 mL acetone as oil phase (at 60℃).100 mg poloxamer188 (F-68) was dissolved in 30 mL water and heated to 60℃as aqueous phase. The oil phase was rapidly injected through an injection needle into a stirring (1000 r-min-1) aqueous phase. LN-SLN suspension was obtained after stirring for 30 min at 60℃.2. Exosyndrom, stability study of LN-SLN and its gelCarbopol 940 was used as matrix in the preparation of LN-SLN gel, in which SLN was added after the gel formed. The exosyndrome and stability study of SLN and SLN gel were carried out. The particles of SLN was sphericity or nearly spherical under transmission electron microscope. LN-SLN and its gel were measured by a laser diffraction particle size analyzer and the diameters were (145.3±6.09) nm and (190.3±1.63) nm, polydispersity index were 0.203±0.01 and 0.267±0.04, Zeta electric potential were (-3.44±0.47) mV and (-21.2±1.02) mV respectively. Results of entrapment efficiency and drug-loading rate of LN-SLN measured by microcolumn centrifugal method were (75.8±0.70) % and (5.17±0.03)% respectively. Contents of LN-SLN and its gel determined by HPLC were (0.47±0.01)mg/mL and (0.023±0.001)% separately. Differential scanning calorimetry analysis indicated that LN encapsulated in SLN was in the amorphism form. LN-SLN was sensitive to highlight (4500±500Lx) and temperature (25,40℃) and could be storied for 10 days at 4℃in the dark condition. SLN gel was stable for 30 days at 4,25 and 40℃respectively.3. Research of LN-SLN gel on skin targetingThe permeation experiments in vitro were performed in a modified Franz diffusion cell through porcine skin. The skin and penetration reception liquid were removed at 2,6,12 h for detecting the accumulation amounts of 0.023% LN-gel, LN-cream, LN-SLN gel and 2% LN-cream(zefnart) in epidermis, dermis and penetration reception liquid.It is hardly for LN to penetrate into reception liquid. LN-SLN gel could significantly increase LN absorption in epidermis and dermis compared to LN-gel and LN-cream. The retention volume per unit area of epidermis(Qe) of LN in LN-SLN gel at 12h was 2.3 times and 11.6 times compared with the LN-gel and LN-cream respectively. The retention volume per unit area of dermis(Qd) of LN in LN-SLN gel at 12h was 2.5 times and 8.5 times compared with LN-gel and LN-cream respectively. None significant differences were found between LN-SLN gel and zefnart on Qe and Qd. Skin uptake rates of LN-SLN gel (0.94%) was about 100 times that of zefnart (0.01%).CONCLUSIONSLN was suitable for loading into SLN, which had a small particle 'diameter, narrow size-distribution, higher entrapment efficiency and stability. LN-SLN gel showed a good ability to target LN to skin. The drug level within the skin was up-therapeutic while uptake rates of LN by skin was raised, which may improve stability of curative effect in clinical.