Stability testing for drug substances and products

Stability testing provides evidence on how the quality of a medication Substance or product fluctuates over a given time period and under the influence of environmental variables including temperature, light and humidity. The studies are designed to include testing of characteristics vulnerable to Change during storage and are likely to influence quality, safety and efficiency. Testing chiefly covers physical, chemical and microbiological attributes.

Stability Testing

  • Physical: Look, melting point, water content, clarity and color of solution, pH, dissolution and disintegration characteristics, viscosity, crystal modification or particle size.
  • Chemical: Assay, degradation products, related compounds and residual solvents
  • Microbial: Growth in germs and efficacy of preservative contents such as antioxidants and antimicrobial preservatives

The frequency of test points for long term studies should be adequate to establish the equilibrium profile for any given period. For drug substances with a proposed re-test period of 12 Months, the frequency of testing at long-term storage condition is usually every 3 months within the first year, every six months within the next year and annually thereafter during the projected re-test period. Recommended test frequency for intermediate storage condition is a minimum of four time points, including the initial and final time points, for a 12-month study. For accelerated storage requirements, test frequency is recommended to be a minimum of three time points, including the initial and final time points for a 6-month study. A drug substance Should be evaluated under storage conditions which test its thermal stability and its sensitivity to moisture.

For long term research, the Stability Testing frequency should Be sufficient to establish the equilibrium profile of the goods. For goods with a proposed shelf life of at least 12 months, the frequency of testing in the long-term storage requirement should usually be every 3 weeks within the first year, every 6 months over the next year, and yearly after that through the proposed shelf life. The use of accelerated storage conditions, typically Elevated temperature and humidity, can offer a snapshot of how the product or substance may change beyond the recommended storage conditions e.g., during transportation as well as providing an indicator of shelf-life before obtaining the results of a two or 3-year study kept at optimum conditions. It is suggested to submit the real time data together with the accelerated information when applying for acceptance and to continue the real time research to the end of their usable shelf-life of the goods.