Background and Importance In response to the lack of paediatric formulation of sodium benzoate in the market, we have been producing 250mg capsules of pure active ingredient (AI), without excipients, intended for patients with urea cycle disorders. The AI content is verified via high-performance liquid chromatography spectrometry, but this method has limitations (high cost and limited availability).

Aim and Objectives The objective of this study was to develop and validate a dosage method of AI to perform routine capsule content testing using UV/Raman spectrophotometry.

Material and Methods After opening the capsule and dissolving the powder in sterile water, we used the QcPrep^® automated system UV/Raman spectrophotometry for AI measurement and identification. The method validation was conducted according to ICH-Q2-R1 criteria. This consisted of six steps. 1) Search for the most relevant spectral band (maximum correlation between absorbance and linearity). 2) Linearity of the calibration curve was assessed between 2.5 and 50.0mg/mL through linear regression and validated if the correlation coefficient (r2) is > 0.999. 3) Repeatability was determined by repeating the analysis (n=6) for the routine dosage concentration (RDC: 25.0mg/mL) and validated if the coefficient of variation (CV) < 2%. 4) Intermediate precision was evaluated by repeating the analysis (n=3) on three different days for the RDC and validated if CV < 5%. 5) Accuracy was assessed at three concentrations, 75%, 100%, and 125% of the RDC (n=3 per concentration) and validated if the deviation was < 5% of the expected value. 6) Specificity was not assessed due to the exclusive composition of the capsules with the AI.

Results The obtained results are as follows:

1. The most relevant spectral band: 279 nm.

2. Linearity: r2 was equal to 0.99993.

3. Repeatability: CV=1.94%.

4. Intermediate precision: CV=0,99%.

5. Accuracy for 75%, 100%, and 125% of the RDC are 0.7%, 0.5%, and 1.1%, respectively.

All criteria met the specified requirements.

Conclusion and Relevance The method is validated: it has demonstrated linearity, repeatability, intermediate precision, and accuracy. The Qc-Prep® is user-friendly, fast, and reliable for the routine content uniformity control of our preparations. The implementation of this pre-release control will be continued for other preparations intended for multiple patients, thereby ensuring the safety of our preparations.

Conflict of Interest No conflict of interest.