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Composition of Cleaning Agents for Pharmaceutical Industries 69
Corrosion Inhibitors
Production equipment that consists of nonferrous metals, tin plated or galvanized
steel, mild steel, or aluminum requires specific corrosion inhibitors. The choice of a
corrosion inhibitor is dependent on many parameters such as the substrate to be
protected, the nature of the detergent, and the pH-value of the solution. Silicates,
modified carbohydrates, and phosphonates are normally used.
VALIDATING THE CLEANING PROCESS
Validation, in general, intends to establish documented evidence that aspecific
process will consistently meet its predetermined objectives. In the case of cleaning
processes, the objective is that the next batch of product, processed in the cleaned
equipment does not become contaminated from any chemical or microbiological
source.
Providing documented evidence that the cleaning does indeed meet this
objective includes selecting an efficient and effective sampling method, deciding
on sampling frequency, finding appropriate assay methods, and setting acceptance
criteria.
This article will not address the issues of properly documenting the cleaning
validation; however, itwill address how to achieve the objective of acleaning
process.
Avoiding contamination of a production batch focuses primarily on
preventing carryover of product residues from aprevious batch. This is especially
important when more than one type of product is produced in the same process
equipment. Acceptance criteria for carryover are based on considerations such as
potency and concentration of the active component, toxicity, etc. How can the level
of previous batch product residue be reduced to the acceptance limit by acleaning
process? As outlined in this article, the success of acleaning process depends on
four basic factors (choice of detergent, cleaning kinetics, solution temperature,
and contact time); unfortunately,there is no “mathematical miracle formula” and in
practice very much depends on previous experiences and test results. When setting
up acleaning procedure, there isusually an “overkill” cleaning program proposed
to be on the safe side. If proven successful, individual parameters can be downscaled
to result in an optimal and “fine tuned” cleaning program that meets
acceptance limits. Cleaning performance tests typically include swab tests and
ringing water analyses. Residues left by the cleaning chemicals are yet another
possible contamination source that should be considered. As with batch product
residues, acceptance criteria for carryover of chemical residues must be determined.
An essential element to consider is whether cleaning chemical components stick
to equipment surfaces or are easily rinsed off. This depends on physicochemical
properties of both the chemical components and the equipment surface (stainless
steel and gasket material).
Because of the vast number of variables, it is difficult to give ageneral outline;
however, an attempt will be made: to give some indications concerning the
rinseability of cleaning agent components. Most ingredients of cleaning agents
have an ionic character. Therefore, they are readily water soluble and can be easily
removed from surfaces by awater rinse. However, depending on the affinity of a
detergenttothe surface material, it must be considered that amonomolecular layer
of that detergent isattached to the surface by adsorption and cannot be removed
by dissolving and dilution. In this case, the adsorption has to be counteracted by