Experimental Design of Accelerated Testing

Estimation ofthe Shelf Life (Expiration Period) of Drug products 

Presently, shelf life is usually estimated by regression analysis according to Eq. (4.8) and its variants using computers. A simplified method for shelf-life estimation, regardless of reaction order, has been proposed,769 2 and various computer programs have been developed. However, it should be noted that the application of Eq. (4.8) is limited to a temperature range in which Ea can be regarded as constant (as discussed in Chapter 2). 

Estimation of Shelf Life Using Accelerated-Test Datu at a Single Level of Temperature 

The shelf life estimated from more than three values of degradation percentage observed at an elevated temperature exhibits a smaller distribution range than that estimated from a single value shown in Fig. 195.775 This is because the use of more than three observed data values provides information on the data variation and enables a Monte Carlo simulation of degradation data.776 This simulation method yields a longer shelf-life estimate because of the smaller distribution range. 

Estimation of Shelf Life under Temperature-Fluctuating Conditions 

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