The glass formulations used at CBL have been selected only after rigorous trials of their ability to maintain products in the fully stable state over the long-term and over a wide temperature range. Of four possible candidate glass formulations stored at 37C for three years, two failed (3&4) and two showed excellent stability (1&2) and are now in daily use. The criterion of success was the ability to maintain the stability of the vaccine at close to the activity of the fresh vaccine in the spray dryer feed mix.
Losses in the failed formulations may have been due to crystallisation of the glass after long-term storage, a common problem with stabilised pharmaceuticals. This is a major reason why other manufacturers recommend that their freeze-dried stabilised material be kept at refrigerator temperature, well below the glass transition temperature of their metastable glass formulations.
Successful formulations have also shown stabilisation for at least 6 months over an exceptionally wide temperature range from freezer temperatures of -20C to +70C. These vaccines are thus suitable for storage at any ambient temperature likely to be encountered on earth!
Most vaccines currently need to be refrigerated or they become inactive. CBL has developed a revolutionary method of stabilising vaccines. It is estimated by the World Health Organisation that currently nearly half of all global vaccines are wasted, partly due to suspected or real temperature damage and as a result millions of children and adults go without life-saving vaccinations. www.who.int
CBL has developed new stabilising glasses that contain different approved glass forming components so as to optimise their properties. For example, we can pre-determine the density of our mixed glasses through the addition of a high-density glass forming component. Other components in our glass formulations ensure a smooth suspension in a non-aqueous, liquid phase preparation.
The first step in the process is to stabilise the vaccines as microspheres by gentle drying in a spray dryer.
The second step is to produce a stable suspension of the microscopic glass spheres in an inert stable non-aqueous liquid that is already approved for clinical use such as a hydrofluoroether (HFE) or a metabolisable oil.
The glass spheres can be specifically tailored to have neutral buoyancy in the chosen suspending liquid by varying the ratio of light and heavy glass forming components during manufacture
Only density balanced formulations are physically stable and instantly injectable. Because both the glasses and the suspension liquids used are stable and inert, the formulations show complete physical and chemical stability on the shelf. For this reason they can, if required, be safely pre-loaded into syringes or other injection devices.
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Cambridge Biostability Limited is a limited company registered in England & Wales with registered number 003630055 and having its registered office at Unit 184, Cambridge Science Park, Milton Road, Cambridge, CB4 0GA, UK.
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