ENHANCED DISSOLUTION OF ITRACONAZOLE BY VACUUM EVAPORATION AT ULTRA LOW TEMPERATURE

Size: px

Start display at page:

Download "ENHANCED DISSOLUTION OF ITRACONAZOLE BY VACUUM EVAPORATION AT ULTRA LOW TEMPERATURE"

Naomi Posy Rice
7 years ago
Views:

1 ENHANCED DISSOLUTION OF ITRACONAZOLE BY VACUUM EVAPORATION AT ULTRA LOW TEMPERATURE P. Sriamornsak, K. Burapapadh, S. Limmatvapirat, J. Nunthanid Department of Pharmaceutical Technology, and Pharmaceutical Biopolymer Group (PBiG), Faculty of Pharmacy, Silpakorn University, Nakhon Pathom Thailand * Tel: , Fax: , pornsak@su.ac.th INTRODUCTION Itraconazole (ITZ) is a potent synthetic triazole antifungal drug with activities against broad spectrum of fungal species. It has a molecular formula C 35 H 38 C l2 N 8 O 4 and molecular weight of , and is a weak basic drug, possessing extremely low water solubility (about 1 ng/ml at neutral ph and 6 μg/ml at ph 1), and pk a of 3.7. The mechanism of action of this compound is similar to all other azole antifungals. It inhibits cytochrome P450 of the fungi and thus interferes in sterol biosynthesis in cell membrane, leading to cell death. According to the biopharmaceutics classification system, itraconazole is an extreme example of a class II compound meaning that its oral bioavailability is determined by dissolution rate in the GI tract [1]. Various techniques have been used to improve the solubility of poorly water-soluble drugs, including size reduction, inclusion complexation, use of surfactants and solid dispersion techniques [2]. For example, improvement of ITZ solubility has been reported by conjugating the drug with hydroxypropyl-β-cyclodextrin followed by fluidized-bed coating of pellets and by the melt extrusion process [3]. However, these processes require specialized preparation techniques and equipment and involve complex manufacturing steps. Recently, ITZ-loaded nanocapsules were prepared from namoemulsion templates and their characteristics were investigated [4]. The aim of the present study was to improve the dissolution of ITZ by a vacuum evaporation at ultra low temperature. The characteristics of the solid particles were observed by powder X-ray diffraction, hot-stage microscopy and scanning electron microscopy. The dissolution behavior of itraconazole from the prepared particles was also investigated. EXPERIMENTAL METHODS Materials All the chemicals used in this research were of standard pharmaceutical grade. Itraconazole was purchased from Nosch Labs Private Ltd. (India), chloroform (CHCl 3 ) and dichloromethane (CH 2 Cl 2 ) from Carl Roth GmbH (Germany). Other reagents were of analytical reagent grade. Preparation of ITZ particles Appropriate quantities of ITZ were dissolved in either CHCl 3 or CH 2 Cl 2 depending on their solubilities. Solutions were left to rest at ambient temperature (25 C) to obtain evaporated solid particles. Vacuum evaporation at ultra low temperature, i.e. the solution was placed in lyophilizer ( 49 C and 0.3 mbar), was also used to prepare the particles. After complete evaporation, samples were dried and kept at containers isolated from light and humidity. Characterization of ITZ particles The melting range of ITZ powder and the prepared solid particles were observed under hotstage microscope ( C temperature range at a rate of 5 C per minute). Powder X-ray diffraction studies were performed using the following experimental conditions: Cu Kα radiation, automatic slit, and a scan rate of 6 per minute between 2 and 45 2θ. Morphology of the powders or particles was observed under a scanning electron microscope. Prior to examination, samples were gold sputter-coated to render them electrically conductive. In-vitro dissolution testing In-vitro dissolution was tested using a USP dissolution testing apparatus I (basket method, 100 rpm, 37±0.5 C). Simulated gastric fluid USP minus pepsin (SGF) was used as a dissolution medium. Samples were taken at predetermined time intervals and determined by HPLC. All experiments were performed in triplicate. RESULTS AND DISCUSSION SEM analysis showed that ITZ particles prepared by simple evaporation in CHCl 3 maintained their

2 morphology while those in CH2 Cl 2 slightly changed but still showed the crystal appearance (Figure 1). In contrast, the ITZ particles prepared by vacuum evaporation at ultra low temperature showed different morphology, i.e. smooth, filmlike structure. (a) Table 1: Melting point ( C) of ITZ raw material powders, particles prepared by evaporation at ambient temperature and by vacuum evaporation at ultra low temperature. CHCl 3 CH 2 Cl 2 Raw material powders Evaporation at ambient temperature Vacuum evaporation at ultra low temperature ITZ powder Evaporation - CHCl3 Evaporation - CH2Cl2 Vacuum Evaporation - CHCl3 Vacuum Evaporation - CH2Cl2 (b) (c) % Drug released (d) (e) Time (min) Figure 2: Dissolution profiles of ITZ from raw material powders and particles prepared by evaporation at ambient temperature and vacuum evaporation at ultra low temperature using CHCl 3 and CH 2 Cl 2 (n=3). ACKHOWLEDGEMENTS Figure 1: SEM micrographs of (a) ITZ raw material powders and ITZ particles prepared by evaporation at ambient temperature using (b) CHCl 3, (c) CH 2 Cl 2, and by vacuum evaporation at ultra low temperature using (d) CHCl 3, (e) CH 2 Cl 2. Powder X-ray diffraction peaks of ITZ can be clearly observed in the raw material powders but completely disappeared in the particles prepared by vacuum evaporation at ultra low temperature, only a broad halo can be observed (data not shown). The onset temperature of melting of ITZ powders and the particles obtained from hotstage microscopy is shown in Table 1. It is obvious that the melting temperature of the vacuum evaporated particles prepared at ultra low temperature was changed to lower temperature, indicating the change in crystal behavior of the ITZ after recrystallization. The dissolution of ITZ powders and particles prepared by simple evaporation was very low (Figure 2), however, particles obtained from vacuum evaporation at ultra low temperature dissolved faster. The authors wish to acknowledge the Thailand Research Fund and Office of Small and Medium Enterprises Promotion, Thailand, for financial support (grant number IUG ). KB is financially supported by Royal Golden Jubilee Ph.D. Program (grant number PHD/0029/2549). Thanks to Pharma Nueva, Co., Ltd. (Thailand) who kindly donated itraconazole samples. REFERENCES [1] Dressman, J.B., Amidon, G., Reppas, C., Shah, V.P. Dissolution testing as a prognostic tool for oral drug absorption: immediate release dosage forms, Pharm. Res. 15, (1998). [2] Fahr A, Liu X. Drug delivery strategies for poorly water-soluble drugs. Expert Opin. Drug Del. 4, (2007). [3] Janssen Pharmaceutica N.V. Antifungal compositions with improved bioavailability. WO Patent 97/44014 (1997). [4] Sriamornsak, P., Burapapadh, K. Composition and preparation process of solid dosage form from nanoemulsion containing pectin and poorly water-soluble drug being able to dissolve rapidly in gastrointestinal tract. Thai Patent Application (2009).

Overview of Dissolution for BA/BE

Overview of Dissolution for BA/BE Biopharmaceutics Classification System based on Solubility/Permeability Biowaivers for BCS I Drugs Discussion of BCS III Drugs Models establishing in vivo-in vitro Correlations (IVIVC Levels A-C) 1 Biopharmaceutics