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Abstract:
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ASTM Standard E2810 provides a methodology for establishing confidence in passing the USP < 905> Uniformity of Dosage Units (UDU) test, and provides acceptance limits for sample means and standard deviations that can be used as elements of lot release. These acceptance limits are quite conservative, however, due to both the nature and shape of an inverted triangular joint confidence region for the lot mean and standard deviation. We obtain improved (wider) acceptance limits by using a Bayesian approach that focuses on the posterior distribution of the probability of passing the USP < 905> UDU test. The Bayesian approach has good sampling properties, and the improvement in acceptance limits can be considerable. For example, for sample size of 10 units and sample means between 97 and 103, the Bayesian approach results in acceptance limits for sample standard deviations that are at least 25% greater than those in E2810. The impact of the improved acceptance limits is illustrated with operating characteristic curves.
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