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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.

Introduction: OC26, an ortho-aryl chalcone compound, shows excellent antitumor activity in vitro and vivo. However, the pharmacokinetic characteristics of OC26 have not been comprehensively reported. It is essential to investigate the correlation of pharmacological response. Objective: To further explore OC26, this study aims to develop an ultra-performance liquid chromatography- tandem mass spectrometric (UPLC-MS/MS) method to reveal the pharmacokinetics and distribution characteristics in rats of OC26. Methods: An UPLC-MS/MS method was developed to detect OC26 in plasma and various tissues. The protein precipitation method was applied to process the biological samples. After intravenous injection 12.5mg/kg of OC26 in rats, plasma and tissue samples were collected from rats and the method was applied to investigate pharmacokinetic and distribution characteristics of OC26. Results: Calibration curve samples of OC26 concentration range from 20 to 2000 ng/mL with the goodness of fit (r2> 0.99). The precisions for the method were within 12.3%, while the accuracies for the method were within ±11% (bias). The matrix effect had no influence on the accuracy and precision of the method. After intravenous injection 12.5mg/kg of OC26 in rats, OC26 was rapidly eliminated (t1/2=31.39±7.87min, MRT0→∞=15.03±2.55min) from rat plasma and widely distributed (Vd=4.83±0.96L/kg) in tissues. The highest concentration of OC26 was detected in the brain in which peak content (~8962.78ng/g at 15min) was over 5-fold higher than that of in other tissues, which prompted new potential targets in the brain. Besides, lung and heart also detected quite a high level of OC26. Benefited from quick elimination in the collected tissues and plasma, long-term accumulation was not observed as chronic toxicity might be less. Conclusions: This UPLC-MS/MS method was successfully applied to detect OC26 and provide a theoretical basis for the further study of OC26.