1. Improving solubility and cellular absorption of Paclitaxel with solid lipid nanoparticles and cyclodextrin Jong-Suep Baek, Jae-Woo So, Ji-Sook Hwang, Cheong-Weon Cho College of Pharmacy, Chungnam National University, Daejeon 305-764, South Korea. INTRODUCTION AIMS Paclitaxel (PTX), the first of a new class of microtubule stabilizing agents, is recognized as an effective chemotherapeutic agent for a wide variety of solid tumors. Clinical application of this highly effective drug in the treatment of cancer is limited because of its poor aqueous solubility and poor oral bioavailability. Therefore, PTX-incorporated SLN, PTX-HPCD and surface- modified PTX-incorporated SLN were prepared and evaluated by the physicochemical and biopharmaceutical characterization in this study. The major peaks of PTX were disappeared in the FT-IR spectra for surface-modified PTX-incorporated SLN. The BET surface area of PTX –incorporated SLN (PS3), and surface-modified PTX-incorporated SLN (FM4) was 4.09 m 2 /g and 4.79 m 2 /g, respectively. Based on the increase of BET surface area of FM4 compared to that of PS3, FM4 showed a 20% of dissolution and the cellular uptake of 29-fold increase compared to that of PS3. Taxol formulation showed 78% of cell viability and FM4 showed 72% of cell viability with 10uM of PTX, indicating FM4 did not show the higher toxicity compared to Taxol formulation. Therefore, FM4 could be good carrier for improving solubility and cellular absorption of water insoluble drug. EXPERIMENTAL METHOD RESULTS AND DISCUSSION CONCLUSIONS 1. Preparation of SLN and SLN+HPCD 1. Solubility and in vitro release 2. SEM and particle characteristics For improving solubility and increasing cellular uptake of PTX into Caco-2 cells, PTX-incorporated SLN, PTX-HPCD and surface-modified PTX- incorporated SLN were prepared and evaluated by the physicochemical and biopharmaceutical characterization. The major peaks of PTX were disappeared in the FT-IR spectra for surface-modified PTX-incorporated SLN. Surface-modified PTX-incorporated SLN with HPCD showed a 20% of dissolution and the cellular uptake of 29-fold increase compared to that of PTX-incorporated SLN. Stearic acid (Lipid) 10mg PTX in EtOH 70 ℃ water bath Sonification 15 min in 70 ℃ water bath Freeze-drying 4 ℃ 10% mannitol Fig 1. low permeability and low solubility of paclitaxel in BCS class Permeability Solubility I II PTX : low solubility low permeability III IV Sonification 15 min in 4 ℃ water bath Surfactant (Poloxamer 188 and lecithin) 10% HPCD Emulsifying step Cooling step Freeze-drying step PTX HPCD PTX incorporated into HPCD Physical mixture PTX Lipid SLN SLN+HPCD SLN+HPCD (physical mixture) SLN HPCD SLN+HPCD Table 1. Solubility of each formulation Fig 2. Dissolution profile of PTX Fig 3. SEM images of PTX (A), SLN (B), SLN+HPCD (C) Particles revealed spherical shape and SLN+HPCD has smaller particle size than SLN. Zeta value was enough to keep in stable status of particles. Table 2. Physical characteristic Fig 6. FT-IR spectra of HPCD (A) and SLN+HPCD (B) (A) (B) (A) Intensity of the PTX major peak (1730cm -1, 1250cm -1 ) was reduced in the case of HPCD incorporation. It was evidence of an interaction at the solid state between PTX and HPCD. (B) Intensity of the lipid major peak (2850cm -1, 1670cm -1 ) was reduced in the case of SLN+HPCD. It was evidence that lipid’s surface was surrounded by HPCD. Fig 7. Caco-2 cellular uptake of each formula 1. Taxol and HPCD was below the LOQ (<0.015%) 2. In case of SLN, Uptake % of PTX was 0.129 (±0.046)% 3. In case of SLN+HPCD, Uptake % was 29 times higher than that of SLN Considering the low solubility of PTX, these formulations significantly increased the PTX solubility. During 36 hours, SLN-HPCD has the highest dissolution profile. After making the SLN formulation, the lipid’s crystallinity was decreased. Fig 5. DSC (A) and XRD (B) (A) (B) a) b) c) 1.5uM as a loading concentration of cellular uptake study was optimal. (72 % viability in SLN+HPCD) 2.IC50 of each formulation is approximately 10~100uM. 3.Because of high permeability of PTX+HPCD, it has more toxicity than Taxol at Caco-2 cell line. Fig 8. Caco-2 cell cytotoxicity study of SLN+HPCD and Taxol Injection speed - 1.5mL/min 4. DSC and XRD 5. FT-IR 6. Cellular uptake study 7. Cytotoxicity study 3. Surface tension Fig 4. Surface tension values of SLN with different surfactant amount * Both lecithin and poloxamer 188 samples, tension was lowest at 75mg (A) (B) (C) Fig 9. HeLA cell cytotoxicity study of SLN and SLN+HPCD 1.IC50 of SLN+HPCD is approximately 10M.