Table 1.
Buffer formulation screening based on lyophilized cake optical appearance immediately after freeze-drying in microtiter plates.
| Acceptable cake apperance | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| no excipient | 1 % trehalose | 2 % trehalose | 1 % sucrose | 2 % sucrose | |||||||||||
| 1 x PBS pH 7.4 | + | + | – | – | – | – | – | – | – | – | – | – | – | – | – |
| 0.1 M potassium phosphate pH 7.0 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| 0.01 M potassium phosphate pH 7.0 | – | – | – | + | + | + | + | + | + | + | – | + | + | + | + |
| 0.1 M potassium phosphate pH 7.4 | x | x | – | – | – | – | – | – | – | + | + | + | – | – | – |
| 0.01 M potassium phosphate pH 7.4 | – | – | – | + | – | + | + | + | + | + | + | + | + | + | + |
| 0.1 M sodium phosphate pH 7.4 | + | + | – | – | + | – | – | – | + | + | + | + | – | – | + |
| 0.01 M sodium phosphate pH 7.4 | – | – | + | + | – | + | + | + | + | + | + | + | + | + | + |
| 0.1 M sodium phosphate pH 7.8 | + | + | + | + | + | – | + | + | + | x | x | x | + | + | + |
| 0.01 M sodium phosphate pH 7.8 | + | – | – | + | + | + | + | + | + | + | + | + | + | + | + |
| 0.1 M Tris-HCl pH 6.8 | – | + | – | – | – | – | – | – | – | – | – | – | – | – | – |
| 0.01 M Tris-HCl pH 6.8 | – | – | – | + | – | – | x | – | x | – | – | – | + | + | + |
Formed or formed but shrunken cakes are assigned a “+” or an “x” when difficult to reconstitute, not-formed or collapsed cakes receive a “-”. Illustration of the corresponding optical appearances is given in Figure 1 . Three values per formulation are resultant from three lyophilized products.