Validation of UV–Vis spectrophotometric colorimetric methods for Rifampicin quantification in PBS & biological matrices

Rifampicin (RIF) is the main treatment for tuberculous meningitis (TBM), but its limited penetration across the blood–brain barrier significantly reduces its therapeutic efficacy. To address this limitation, smart-pH nanoparticles were designed to release RIF in inflamed area and incorperated into a thermosensitive in situ gel for enhanced drug delivery via the olfactory nerve.
UV–Vis spectrophotometry and colorimetric methods to quantify RIF in various media and biological matrices, including phosphate-buffered saline (PBS) at pH 7.4 and 5.0, plasma, and brain tissue. The main validation parameters assessed were selectivity, specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, extraction recovery, and dilution integrity.
Method validation followed International Council for Harmonization (ICH) guidelines, demonstrating excellent linearity (r2 = 0.999) and lower limit detection (LOD) of approximately 0,25–0.49 μg/mL were achieved in all media. The method demonstrated high accuracy (%RE −11.62% to 14.88%) and precision (%RSD 2.06% to 13.29%), meeting regulatory requirements.
This validated approach enables reliable RIF quantification in biological samples, supporting its application in in vitro release studies, ex vivo permeability studies, and in vivo pharmacokinetic evaluations. These findings contribute to the advancement of targeted drug delivery systems for TBM treatment.
This study discussed the validation of an analytical method to quantify rifampicin (RIF) in the development of a new RIF delivery system. Smart pH-responsive nanoparticles were designed for pH-sensitive drug delivery targeted for TBM therapy. SPN-RIF was incorporated into a thermosensitive in situ gel to increase the contact time with the nasal mucosa. Therefore, a valid analytical method was required for the development process. The UV–Vis spectrophotometric colorimetric method was proven to be a valid, simple, and practical approach for quantifying RIF in PBS and biological matrices.