Lyophilization is often used to increase the stability and shelf life of proteins which are physically and/or chemically unstable in aqueous solution. Freeze drying removes water protein solutions, including water from the protein surface which plays a major role within the protein structure, and this frequently causes damage. An appropriate choice of stabilising additives is necessary to protect the protein from the denaturing during both the freezing and the dehydration. The components of the excipients displace water by replacement, which makes the drying possible without causing damages to the proteins. In addition the solidification of the excipients forms a matrix around the particles which keeps the protein in their native structures.