Control of impurities in biological and botanical products

Although it may not always be possible to control the sources or extraction conditions to produce only a single component, they should be arranged so as to produce, as far as possible, a consistent mixture. Impurity profiles of botanical products are often monitored by a number of anal3hical procedures to ensure product quality. Minor components that have pharmacological activity should not necessarily be viewed as impurities. In some cases, the activity of a botanical or fermentation drug substance may be attributed to a number of components. 

In many cases, biotechnology-derived products may have many components that have biological activity. The aim should be to devise controls that monitor the various components so as to retain a consistent potency and purity. For example, the USP monograph for erythromycin [9] indicates that the principal component is erythromycin A and that the percentage of erythromycin A, erythromycin B, and erythromycin C is not less than 85.0% and not more than 100.5%. Within these parameters, the relative ratios of erythromycins A, B, and C may change. This is not always the case for biotechnology-derived products, however. For example, the USP monograph for amoxicillin [10] allows for only one active component. 

It is not uncommon for facilities to be dedicated for processing only one, or only one type of, drug substance to avoid cross-contamination. For example, some people are allergic to the penicillins, and fatal reactions are known to occur. 

Facilities for the manufacture of penicillins are frequently dedicated so that other drugs will not be contaminated with even small amounts of these potential allergens. 

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