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A Odidi

Publications and source records attributed to A Odidi.

3 recordsLinked to original sources
PubMed2000

Characterization of wet masses of pharmaceutical powders by triaxial compression test.

The mechanical and rheologic properties of wet masses of pharmaceutical powders determine their processibility and the quality of the product prepared by extrusion/spheronization. In this work, a triaxial compression test was attempted for the first time to characterize material properties of pharmaceutical wet masses of different hydrophilicity and particle sizes. The stress-strain curves and the pore pressure were determined at various cell pressures. The failure criteria of the wet masses were obtained from the stress path on the deviator stress plane. The cohesion (c) and the angle of internal friction (phi) were evaluated from the intercept and the slope of the failure loci. The stress-strain behavior strongly depended on the type of powders and cell pressure. The values of c and phi were similar for wet masses of EC FP, MCC PH101, and SMCC 50, but a very small phi and a very high c value for HPMC. The shear strength and rigidity of the wet masses were in the order of EC FP > SMCC 50 > MCC PH101 > HPMC, whereas the elastic recovery was in the opposite order. These material parameters could be used as references for selection of excipients and formulation for extrusion/spheronization.

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PubMed1998

Scale effect in bioequivalence evaluations.

OBJECTIVE: The objective of the study was to evaluate the relationship between the magnitude of the sample means for a bioavailability measure and the ratio of the sample means in bioequivalence evaluations. METHODS: We assumed that bioavailability data were obtained from crossover trials on a test and a reference drug products. The true test-reference ratio was constructed as a function of dosage strength under certain dose-response relationship assumptions, and was used for deriving analytical results of assessing the scale effect due to dosage strength. In addition, the test-reference ratio of sample means was constructed as a function of the true test-reference ratio and the correlated sampling deviation in the sample means, and was used in a deterministic simulation for quantifying the scale effect due to the correlated sampling deviation. RESULTS: The major systematic factors that influence the magnitude of the sample means include the dosage strength, dose-response relationship, and the positively correlated sampling deviation in the sample means. RESULTS of this study showed that the true test-reference ratios can be improved with increasing dosage strength in most of the situations studied, but at a diminishing rate. The correlated sampling deviation can alter the test-reference ratio of the sample means through changing magnitude of the sample means, especially for drug products with low bioavailability. CONCLUSIONS: For extended release drug products with multiple dosage strengths, the development efforts should focus on the lowest strength if there is little or no formulation by dose interaction effect. Pilot studies should be conducted for both the highest and the lowest strength instead for possible formulation by dose interaction effect. The magnitude of observed means for bioavailability measures on the reference drug product can indicate the degree of systematic variation in the ratio of means. The expected mean values of the reference drug product can be derived from previous trial(s) and/or from other information sources. If the sample mean for the reference drug product in a failed bioequivalence trial is lower than expected, the investigator should consider repeating the trial.

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