Preservatives testing

The unfolding behavior of multidomain proteins in the presence of preservatives has also been evaluated. For example, IL-1R (type I) has three domains that correspond to three unfolding transitions as measured by microcalorimetry and depicted in Figure 13.1.31 All three transitions exhibit some shift to lower Tm in the presence of the three preservatives tested (i.e., 0.065% phenol, 0.1% metacresol, and 0.9% benzyl alcohol), in comparison to a control containing no preservative. Such a destabilization could have consequences for the shelf-life of the product. Another example of the impact of preservatives on a multidomain protein is illustrated in Figure 13.5. The protein is fused to a single IgCi, Fc. The... 

Hence, a generic or universal HPLC method interfaced with a UV detector for BHT can be used on any drug as long as the acceptance criteria on accuracy, precision, robustness, and other necessary requirements have been met. Similar to appearance, drug release, assay, and impurities, preservative testing is also required if a certain degree of preservative has to be included in the drug product to ensure an adequate shelf life. 

Detection of Preservatives.—Tests are made especially for salicylic acid, boric acid and formaldehyde, the methods given for wine being employed. 

If the product is not a disinfectant formula, it may be advisable to conduct adequacy of preservation tests. In these tests, the formula, as made for sale, is challenged with various microorganisms. This test sample is incubated for a time, and the amount of growth measured. Aging tests for the shelf life of the formula are also advisable, usually run for up to 12 to 18 weeks at both room temperature and elevated temperatures. 

Centrifugation of urine decreased the mercury content of the liquid phase (Lindstrom, 1959). Full recovery of mercury added in urine could only be achieved if the specimen was vigorously shaken before analysis. None of the preservatives tested could prevent this loss (Trujillo et al., 1974),... 

European Standard EN 113, 1996. Wood Preservatives - Test method for determining the protective effectiveness against wood destroying basidiomycetes - Determination of toxic values. 

Wood Preservatives - Test Method for Determining the Protective Effectiveness Against Wood Destroying Basidiomycetes - Determination of the Toxic Values. Normenausschuss Materialpriifung (NMP) im DIN, Beuth Verlag, Berlin. 

Of all the ophthalmic preservatives tested in rabbits only benzalkonium chloride caused significant damage to all the cellular components of the cornea including the endothelium. 

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