Research J. Pharm. and Tech. 5(7): July 2012 985 ISSN 0974-3618 www.rjptonline.org RESEARCH ARTICLE Optimization of Freeze Drying Cycle Protocol Using Real Time Microscopy and Integrated Differential Thermal Analysis-Electrical Impedance Ashok A. Hajare* 1 , Harinath N. More, Pravin S. Walekar and Digvijay A. Hajare Department of Pharmaceutical Technology, Bharati Vidyapeeth College of Pharmacy, Kolhapur- 416 013, India *Corresponding Author E-mail: ashok.hajare@bharatividyapeeth.edu ABSTRACT: The objective of the research work was to use freeze dry microscopy (FDM) and differential thermal analysis (DTA)/electrical impedance (EI) for human serum albumin (HSA) freezing solution to determine the freeze drying cycle (FDC) to ensure acceptable cake integrity, reconstitution time and long-term stability. The HSA solutions with stabilizers were freeze dried at -40ºC and 0.06hPa for 72h. HSA content was determined by reverse phase high performance liquid chromatography (RP-HPLC). Optimized composition was used to determine critical temperature by FDM and DTA/EI. Based on observations FDC was designed and the optimized composition was processed. Freeze dried products were visually inspected for morphology. Reconstitution time was determined by Thiermann method and residual moisture analysis by Karl Fischer titration. Freeze dried products were investigated for glass transition temperature using differential scanning calorimetry (DSC) and for amorphization using x-ray diffractometry (XRD), respectively. FDM and integrated DTA/EI studies provided specific information required for primary drying to process HSA compositions. Highest HSA recovery was observed in composition containing 1%w/v HSA, 25%w/v sucrose, 1.0%w/v sodium dihydrogen phosphate and 0.3%w/v polyvinylpyrrolidone K30. Reconstitution times of products were 15-20 sec. Residual moisture content was below 3%w/w retaining 99.56%w/v of HSA. XRD pattern indicated amorphous nature of material. DSC thermogram showed T g well above storage temperature. Results revealed need of thorough understanding of freezing and annealing temperatures, shelf temperature, vacuum level and its duration during processing for freeze drying. Development and validation of efficient and economical FDC for HSA can be designed using FDM and DTA/EI. KEYWORDS: Freeze dry microscopy; Differential thermal analysis; Electrical impedance; Freeze drying; Human serum albumin. INTRODUCTION: Freeze drying, as a unit operation in the production of parenteral drugs, is becoming more prevalent because many of the new molecular entities coming out of discovery have less than two years of shelf life before they expire. Formulators usually use large-scale machines to determine the right conditions for freeze-drying products and extending shelf life, which can makes, this process the most expensive and time consuming (1). Each active pharmaceutical ingredient has limitations and requirements that either prevent or promote the addition of certain excipients desirable for the lyophilization process (2). A freeze dried formulation generally consists of various excipients such as sugars and polymers or proteins to stabilize biomolecule conformation against denaturation which is caused by water removal during freeze drying. Received on 26.05.2012 Modified on 22.06.2012 Accepted on 08.07.2012 © RJPT All right reserved Research J. Pharm. and Tech. 5(7): July 2012; Page 985-991 These excipients usually remain amorphous during and after freeze drying. Due to use of improper FDC protocol the excipients used in these formulations are usually expected to be in crystalline state after processing. Crystallization of excipients generally tends to eliminate any stabilizing effect of the excipients on the biomolecules(3). An integral part of designing a formulation is the characterization of its behavior using one or more appropriate analytical methods to gain insight into the critical processing temperature for processing. The intent of low temperature thermal analysis is to identify the critical values for freezing and primary drying as well as the characteristics that contribute to the behavior of a product during processing. The freezing method has a significant effect on the structure of the ice formed, affecting both the water-vapor flow during primary drying and the final product. By increasing the primary drying shelf temperature, the rate of sublimation is increased.