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Background: The development of innovative approaches in drug analysis is a challenging task for medicine, pharmacy, and engineering sciences. For instance, the requirement of proper dosage forms in releasing active ingredients is crucial. It is essential to analyze drugs in biological liquids for early diagnosis and treatment purposes. Drug analysis is also of great importance to control the quality of pharmaceutical products, test their efficacy, and develop novel drug formulation. The present review is aimed to highlight the most recent spectrophotometric approaches applied to analyze various classes of drugs in biological media and/or dosage forms. Methods: Direct and derivative UV/UV-Vis spectrophotometry and a combination of various techniques with spectrophotometry, such as injection analysis and chemometrics, have most widely been applied in the analysis of dosage forms. In addition, emerging technologies, such as UV imaging allows to obtain the distribution of drug concentration in time-resolved 2D images based on UV light absorption, utilization of nanotechnology, self-assembled nanomaterials, and aptamer-based nanoparticles have gained interests to investigate drug assays and to quantify the proper drug release. Results: Due to their high versatility, ease of application, low cost, and fast response, spectrophotometric methods are one of the most preferable methods providing high accuracy and precision with a wide linear range in drug analysis. Conclusion: Selected examples demonstrating the applicability of spectrophotometric methods in pharmaceutical assays in this review might contribute to the overall importance of the analytical test used in modern pharmaceutical analysis.

Background: The number of validated quantification methods for rifampicin, a prototypical Oatp inhibitor, in biological rat samples was limited. Objective: This study was conducted to validate a modified reversed-phase liquid chromatographic method for the determination of rifampicin in rat liver tissue according to the current ICH M10 Bioanalytical Method Validation Draft Guideline (2019) for application to samples of in situ rat liver perfusion studies. Methods: Liver tissue samples were obtained from recirculatory in situ rat liver perfusion studies. The analysis was performed on a C18 column with a mobile phase composed of 0.05 M phosphate buffer (pH 4.58): acetonitrile (55:45, v/v). The assay was validated for selectivity, calibration curve and range, matrix effect, carry-over, accuracy and precision, reinjection reproducibility, and stability. Results: he method was considered selective and stable, without having carry-over and matrix effects. The calibration curve was linear (R2: 0.9983) within the calibration range (0.5-60 ppm). Accuracy and precision values fulfilled the required limits. Liver concentrations of rifampicin in liver tissue, obtained after 60 min perfusion with 10 μM and 50 μM of rifampicin, were 45.1 ± 11.2 and 313.4 ± 84.4 μM, respectively. Conclusion: The bioanalytical method validation was completed and the method was successfully applied for the determination of rifampicin in rat liver tissue.

Background: The number of validated quantification methods for rifampicin, a prototypical Oatp inhibitor, in biological rat samples is limited.

A novel, fast, easy liquid chromatographic method was developed for simultaneous determination of metformin hydrochloride, phenol red, metoprolol tartrate for intestinal perfusion studies. The analysis was performed on a C-18 column with a mobile phase composed of phosphate buffer (pH 3.0, 100 mM)-acetonitrile (30: 70, v/v). Method was validated for selectivity, sensitivity, linearity, precision, accuracy, stability. All calibration curves were linear (r > 0.9986). Quantification limit was 2.5 mu g/mL for metformin, 0.38 mu g/mL for phenol red, 0.77 mu g/mL for metoprolol. Detection limit was 0.85 mu g/mL for metformin, 0.12 mu g/mL for phenol red, and 0.25 mu g/mL for metoprolol. Precision and accuracy values of the method fulfilled the required limits. The mean permeability values of metformin across jejunum, ileum and colon were 5.59 +/- 3.09, 11.5 +/- 1.26, 7.86 +/- 2.65 x 10(-5) cm/s, respectively; the corresponding values for metoprolol were 5.77 +/- 3.37, 4.33 +/- 0.48 and 10.5 +/- 3.15x10-5 cm/s. These results demonstrate that permeability of metformin across jejunum and colon can be classified as low, whereas its permeability is high across ileum.

Objectives According to Biopharmaceutics Classification System (BCS), acyclovir is a class III (high solubility, low permeability) compound, and it is transported through paracellular route by passive diffusion. The aim of this study was to investigate the effect of various pharmaceutical excipients on the intestinal permeability of acyclovir.