Lyophilized products are prepared using freeze-drying to extend the shelf life of drugs, especially those sensitive to heat or moisture.
Steps in Lyophilization:
Preparation of Solution:
The drug is dissolved in a suitable vehicle with excipients such as:
Stabilizers: Protect drug integrity (e.g., sucrose, trehalose).
Bulking Agents: Add volume for uniform freeze-drying (e.g., mannitol).
Buffers: Maintain pH for stability.
Freezing:
The solution is frozen to form solid ice crystals.
Primary Drying (Sublimation):
Water is removed by sublimation under vacuum at low temperatures.
Secondary Drying (Desorption):
Residual moisture is removed to ensure product stability.
Sealing:
Vials are sealed under vacuum or inert gas to maintain sterility and stability.
Advantages of Lyophilization:
Improved stability of heat-sensitive drugs.
Retains biological activity of proteins and peptides.
Easy reconstitution before administration.
Examples:
Vaccines, monoclonal antibodies, and peptides like insulin.