Some Practical Aspects - Freeze-drying of Pharmaceuticals and Biopharmaceuticals - page 125

One also deals with a batch process with a reputation for high running
costs; some consideration should therefore be given to the economics of
the process.
Factors to be considered are as follows:
Power (electricity)
Rent/space
Labour
Ancillary processes
Capital depreciation.
Freeze-drying can be shown to be an energetically inefficient process, but
is it therefore necessarily expensive to run? A typical freeze-drier with a
sufficient capacity to dry 100 kg of solution dispensed in 2-ml portions
with a 5-mm fill depth and T g of 40 1 C has a power rating of 80 kW.
For a ''typical'' freeze-drying cycle of 65 h, it would be possible to dry 40
batches annually. Energy (electricity) costs would be of the order of 0.5
cents per vial, whereas the purchase cost of the equipment, depreciated
over 5 years, would amount to ca. 7.5 cents per vial. In practice,
therefore, power costs tend to be insignificant compared to the value
of ''the product'' and, when compared to the cost of (purified) raw
materials, packaging and pre- and post-drying operations (e.g. filling
and QA) make only a minor contribution to the overall M&A costs. The
''fixed'' costs include rent/buildings, manpower for servicing produc-
tion, filling, packaging and depreciation. The ''capital cost'' and, hence,
''depreciation'' of the equipment can be a significant factor.
Other economic considerations that affect the manufacturing cost of
the product include:
Size/capacity
Shift working patterns
Length of cycle times/overall plant throughput
The ''fear factor'' (is it prudent to risk one large freeze-drier run,
where breakdowns can be catastrophic, or would two smaller
freeze-driers be preferable?)
Escalation of QC/QA costs with smaller batch sizes.
The final ''cost'' of a product will ultimately depend upon the accounting
practices of the manufacturing company. Cycle time, however, is often
singled out as an easily measurable parameter to which costs can be
scaled. It is not unusual for management to exert pressure for a reduction
in the cycle time. With any given formulation/fill volume/vial geometry