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Robert Chisholm

Publications and source records attributed to Robert Chisholm.

3 recordsLinked to original sources

Process analytical technology case study part I: feasibility studies for quantitative near-infrared method development.

This article is the first of a series of articles detailing the development of near-infrared (NIR) methods for solid-dosage form analysis. Experiments were conducted at the Duquesne University Center for Pharmaceutical Technology to qualify the capabilities of instrumentation and sample handling systems, evaluate the potential effect of one source of a process signature on calibration development, and compare the utility of reflection and transmission data collection methods. A database of 572 production-scale sample spectra was used to evaluate the interbatch spectral variability of samples produced under routine manufacturing conditions. A second database of 540 spectra from samples produced under various compression conditions was analyzed to determine the feasibility of pooling spectral data acquired from samples produced at diverse scales. Instrument qualification tests were performed, and appropriate limits for instrument performance were established. To evaluate the repeatability of the sample positioning system, multiple measurements of a single tablet were collected. With the application of appropriate spectral preprocessing techniques, sample repositioning error was found to be insignificant with respect to NIR analyses of product quality attributes. Sample shielding was demonstrated to be unnecessary for transmission analyses. A process signature was identified in the reflection data. Additional tests demonstrated that the process signature was largely orthogonal to spectral variation because of hardness. Principal component analysis of the compression sample set data demonstrated the potential for quantitative model development. For the data sets studied, reflection analysis was demonstrated to be more robust than transmission analysis.

Feasibility Studies↗

Process analytical technology case study: part II. Development and validation of quantitative near-infrared calibrations in support of a process analytical technology application for real-time release.

This article is the second of a series of articles detailing the development of near-infrared (NIR) methods for solid dosage-form analysis. Experiments were conducted at the Duquesne University Center for Pharmaceutical Technology to demonstrate a method for developing and validating NIR models for the analysis of active pharmaceutical ingredient (API) content and hardness of a solid dosage form. Robustness and cross-validation testing were used to optimize the API content and hardness models. For the API content calibration, the optimal model was determined as multiplicative scatter correction with Savitsky-Golay first-derivative preprocessing followed by partial least-squares (PLS) regression including 4 latent variables. API content calibration achieved root mean squared error (RMSE) and root mean square error of cross validation (RMSECV) of 1.48 and 1.80 mg, respectively. PLS regression and baseline-fit calibration models were compared for the prediction of tablet hardness. Based on robustness testing, PLS regression was selected for the final hardness model, with RMSE and RMSECV of 8.1 and 8.8 N, respectively. Validation testing indicated that API content and hardness of production-scale tablets is predicted with root mean square error of prediction of 1.04 mg and 8.5 N, respectively. Explicit robustness testing for high-flux noise and wavelength uncertainty demonstrated the robustness of the API concentration calibration model with respect to normal instrument operating conditions.

Computer Systems↗

Is thyroid frozen section too much for too little?

BACKGROUND: The role of frozen section (FS) in thyroid disease is controversial. The goal of this study was to identify a cohort of patients who may or may not benefit from FS. METHODS: Two hundred thirty-one patients who underwent thyroidectomy were evaluated in regard to fine-needle aspiration (FNA), FS, and the extent of surgery. RESULTS: In all, 155 patients underwent FNA, 140 patients underwent FS, and 103 patients had both. A final diagnosis of malignancy was obtained in 47 of 231 patients. FNA had a sensitivity of 50% and a specificity of 99%, and FS had a sensitivity of 50% and a specificity of 100% for diagnosing malignancy. Accounting for the clinical findings and FNA results, FS results altered the extent of thyroidectomy in 1 of 103 patients. CONCLUSIONS: The increased costs for the operative time and the pathologists needed to obtain routine FS are not supported with any substantial benefit in patient outcome.

Adolescent↗