An Investigation into Improvement of Stability and Efficacy of Intravesical BCG Formulations Using Freeze-Drying Technique

Abstract

Bacillus Calmette–Guérin (BCG) has been used as an intravesical product for the treatment of intermediate and high risk, non-muscle-invasive bladder cancer (NMIBC). Freeze drying technique is highly recommended for product development, however, the microorganism sensitivity to freezing and drying processes is a major chalenge which may lead to poor survival. To overcome this problem, the use of cryoprotectants in intravesical BCG formulation is required. This study was, therefre, planned to design a new formulation, using an attenuated strain of Mycobacterium bovis, which could be produced by freeze drying technique with the aim of prolonging its storage stability and increasing its efficacy as well as the ease of administration. For this purpose, sodium L-glutamate monohydrate (a commonly used stabilizer in domestic BCG suspension formulations) was replaced by lactose monohydrate. New intravesical BCG formulations, both in lyophilized and liquid forms, were eventually evaluated by moisture content assay, viable count assay, bacterial and fungal contamination, safety test and determination of bacterial concentration and O2 consumption. The results were compared with the data obtained for the conventional lyophilized and liquid products. Maximum survival rate was achieved in the presence of 10 % w/v lactose monohydrate for both liquid and lyophilized formulations when stored at less than -10 and 2-8C, respectively. In summary, the freeze-dried formulations developed with lactose monohydrate met the requirements of intravesical BCG in high viability and stability during storage. HIGHLIGHTS • Lyophilization technique and lactose monohydrate as a protecting sugar were used to improve the stability, storage conditions, shelf-life and effcicay of intravesical BCG product. • Maximum survival rate was attained for both liquid and lyophilized lactose-based formulations prepared with 10 %w/v lactose monohydrate and stored at less than -10 and 2-8°C, respectively. • Freeze-dried products possessed higher stability and efficacy in comparison with corresponding liquid preparations.

Keywords

• bacillus calmette–guérin
• cryoprotectant
• freeze drying
• intravesical bcg
• lactose monohydrate
• mycobacterium bovis