Top-down evaluation of the matrix effects in microbial enumeration test uncertainty

Measurement uncertainty for < 905 > Uniformity of Dosage Units tests using Monte Carlo and bootstrapping methods - Uncertainties arising from sampling and analytical steps

Uniformity of dosage unit (UDU) test is widely used to assess the quality, safety, and effectiveness of dosage forms in unit doses. An increased variability of the amount of drug (API - Active Pharmaceutical Ingredient) in each dose unit may lead to low quality, unsafety, and ineffective medicines. The aim of this work was to evaluate the measurement uncertainty associated with the acceptance value (AV) using the Monte Carlo and Bootstrapping methods, as well as to estimate the risk of false decisions regarding compliance/non-compliance due to uncertainty. Haloperidon 5 mg tablets and ofloxacin 200 mg tablets were subject to content uniformity (CU) and weight variation (WV) tests, respectively. Measurement uncertainty evaluation of UDU tests considered both uncertainties arising from sampling analytical steps. Uncertainty values were quantified using Monte Carlo (sampling) or bootstrapping (resampling) methods. Confidence intervals at 95% confidence level (CI95%) for AV value obtained for haloperidol 5 mg tablets were found to between 8.1 and15.8 and between 8.1 and 16.9 for Boostrapping and Monte Carlo methods, respectively. There is an increased risk of false conformity assessment for haloperidol UDU test (6.5% and 12.1% risk values for Bootstrapping and Monte Carlo methods). Considering the ofloxacin 200 mg tablets, the CI95% for AV value were found to be between 4.0 and 11.3 and between 4.9 and 11.4 for Bootstrapping and Monte Carlo methods, respectively. Uncertainty arising from sampling and analytical steps were both relevant to the overall uncertainty of AV values. Measurement uncertainty evaluation provided relevant information to support conformity assessments with a reduced risk of false decision making.

Measurement uncertainty evaluation and risk of false conformity assessment for microbial enumeration tests

Microbial enumeration tests are widely used to assess the microbiological quality of non-sterile pharmaceutical products. Despite of all efforts to guarantee the reliability of microbial enumeration tests, there will always be an uncertainty associated with the measured values, which can lead to false conformity/non-conformity decisions. In this work, we evaluated the measurement uncertainty using a bottom-up approach and estimate the consumer's or producer's risk due to the measurement uncertainty. Three main sources of uncertainty were identified and quantified: dilution factor, plated volume, and microbial plate counts. The contribution of these sources of uncertainty depends on the measured value of microbial load in pharmaceutical products. The contribution of dilution factor and plated volume uncertainties increase with an increase of measured value, while the contribution of microbial plate count uncertainty decreases with an increase of measured value. The overall uncertainty values were expressed as uncertainty factors, which provide an asymmetric 95% level confidence level of microbial load in pharmaceutical products. In addition, the risk of false conformity/non-conformity decisions due to measurement uncertainty was assess using Monte Carlo method. When the measured value is close to the upper specification limit and/or the measurement uncertainty is large, the risk of false conformity/non-conformity decisions may be significantly high. Thus, we conclude that the use of uncertainty factor in the conformity/non-conformity assessment is important to guarantee the reliability of microbial enumeration test results and to support decision-making.

Measurement Uncertainty and Conformity Assessment Applied to Drug and Medicine Analyses - A Review

Analytical results are often used in scientific research, industrial and clinical applications to support decision making. Despite all efforts to ensure the reliability of analytical results (including method validation, internal quality control, use of certified reference materials, proficiency tests, and ISO 17025 accreditation), there will always be an uncertainty associated with the measured value. The measurement uncertainty expresses the quality of the analytical result and allows the comparability between analytical results or between the measured value and the specification limit(s). This work discusses the importance of measurement uncertainty, including the steps involved in the measurement uncertainty evaluation, the bottom-up and top-down approaches used in measurement uncertainty calculation, the measurement uncertainty evaluation in drug and medicine analyses, and the application of measurement uncertainty in conformity assessment for quality control, stability studies, and pharmaceutical equivalence.