246 METHOD VALIDATION OF SIMVASTATIN IN PCL-PEG-PCL TRIBLOCK COPOLYMER MICELLES USING UV-VIS SPECTROPHOTOMETRIC FOR SOLUBILITY ENHANCEMENT ASSAY Original Article DEWI PATMAYUNI 1# , T. N. SAIFULLAH SULAIMAN 2 , ABDUL KARIM ZULKARNAIN 2 , SHAUM SHIYAN 3 1 Bhakti Pertiwi, School of Pharmacy Science, Palembang 30128 Indonesia, 2 Departement of Pharmaceutics, Faculty of Pharmacy, Gadjah Mada University, Yogyakarta 55281 Indonesia, 3 Departement of Pharmacy, Faculty of Mathematics and Natural Sciences, Sriwijaya University, Indralaya 30622 Indonesia Email: dewiozorapatmayuni@ymail.com Received: 24 Aug 2021, Revised and Accepted: 14 Oct 2021 ABSTRACT Objective: This study aims to increase the solubility of simvastatin (SIM), a hydrophobic drug, by incorporating it into PCL-PEG-PCL triblock copolymer micelles and validating the assay method used, namely Uv-Vis spectrophotometric. Methods: The shake flask method was used to determine the increase in solubility experienced by SIM after being incorporated into the micellar system. The values of maximum wavelength (λmax), linearity, LOD, LOQ, accuracy, and precision were used as parameters measured to assess the validity of the assay method used. Results: The results showed that PCL-PEG-PCL triblock copolymer micelles could increase SIM solubility by 9.7 times (89.49±5.75 µg/ml) compared to SIM without modification (9.19±0.24 µg/ml). The validation results show the λmax value of 239 nm, a linear calibration curve with an R- value of 0.9994, LOD and LOQ of 0.33 µg/ml and 1.00 µg/ml, accurate measurement with recovery at concentrations of 80%, 100%, and 120% were 102.93±1.32%, 100.78±0.40%, and 104.58±0.79% and also had good precision with RSD<2%. Conclusion: The PCL-PEG-PCL triblock copolymer micelles can increase SIM solubility and the Uv-Vis spectrophotometric method has been validated successfully for the quantitative analysis of SIM in PCL-PEG-PCL triblock copolymer micelles. Keywords: Simvastatin, Triblock copolymer, PCL, PEG, Validation, Uv-Vis spectrophotometric © 2022 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open-access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/) DOI: https://dx.doi.org/10.22159/ijap.2022v14i1.42961. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Solubility is one of the physicochemical properties of drugs that need to be considered because it can affect the formulation and effectiveness of therapy. Drugs with low solubility (hydrophobic drugs) will provide low bioavailability so that the desired therapeutic effect is not perfect [1, 2]. SIM (C25H38O5) is an anticholesterol drug of the statin class with the mechanism of action of inhibiting the enzyme 3-hydroxy-3-methyl glutaryc-coenzyme A reductase (HMG-CoA reductase). SIM belongs to the class II biopharmaceutical classification system (BCS) with a solubility of 0.01 g/l (practically insoluble) and a bioavailability of<5% [3-6]. Many attempts have been made to increase the solubility of SIM, including hydrogels [7], complexes with arginine [8], solid dispersions [9, 10], micellar polymers with derivatives of tocopherol [11], spherical crystal [12], and co-crystal formation [13, 14]. In this study, the increase in the solubility of SIM was carried out by being incorporated into PCL- PEG-PCL triblock copolymer micelles which would then form a micellar polymer. PCL-PEG-PCL triblock copolymer micelles are an ideal drug carrier candidate for SIM with an entrapment efficiency of 87.74% [15]. To determine the increase in solubility experienced by SIM, it is necessary to determine the concentration of SIM in the PCL-PEG-PCL triblock copolymer micelle. According to the pharmacopeia, SIM levels were determined by the High-Performance Liquid Chromatography (HPLC) method. However, a simpler method, UV- Vis spectrophotometry, has been reported to be used for the assay of SIM in several pharmaceutical preparations showing results that meet the required acceptance criteria [16-19]. MATERIALS AND METHODS Materials SIM is provided free by Dexa Medica (Palembang-Indonesia). All other chemicals and reagents used in this study met the criteria for an analytical grade. Preparation of PCL-PEG-PCL triblock copolymer and SIM loaded PCL-PEG-PCL triblock copolymer micelles The preparation of PCL-PEG-PCL triblock copolymer and incorporated SIM into the micelles system was obtained from our previous study. Where PCL-PEG-PCL triblock copolymer is made by reacting 5 g of PEG and 10 g of ɛ-CL using Sn (Oct)2 0.5% w/w as a catalyst by the ring- opening polymerization method (ROP). While SIM was incorporated into the polymeric micelles by the solvent evaporation method (film formation), 1 ml of SIM stock solution in dichloromethane (100 mg/10 ml) was mixed with 50 mg of PCL-PEG-PCL triblock copolymer [15]. Preparation of SIM stock solution SIM was weighed as much as 10 mg, put into a 25 ml volumetric flask, and methanol was added to the mark and then homogenized to obtain a concentration of 400 ppm [16]. Determination of the λmax of SIM The 0.05 ml of the stock solution is pipetted, put into a 5 ml volumetric flask, distilled water is added to the limit mark and homogenized to obtain a solution with a concentration of 4 ppm, then the solution is measured using a UV-vis spectrophotometer over a 200-300 nm wavelength range. The λmax of SIM is indicated by the wavelength that gives the highest absorbance [16]. Preparation of SIM calibration curve The stock solution was pipetted as much as each 0.050, 0.075, 0.100, 0.125, 0.150, and 0.175 ml were put into a 5 ml volumetric flask, and then distilled water was added to the mark and homogenized to obtain a serial solution with a concentration of 4, 6, 8, 10, 12 and 14 ppm. The series solution was measured with a UV-vis spectrophotometer at the λmax of SIM [16]. Solubility enhancement test of SIM in the PCL-PEG-PCL triblock copolymer micelles SIM excess (10 mg) and SIM loaded into PCL-PEG-PCL triblock copolymer was dissolved in 10 ml of distilled water and shaken for 24 h International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 14, Issue 1, 2022