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Single-pass intestinal perfusion (SPIP) method is a widely used experimental model to determine the intestinal permeability of drugs. These studies are performed in the presence of a reference standard (metoprolol, MT) and a zero permeability marker (phenol red, PR). Therefore, it is important to develop a validated method for simultaneous determination of the investigated compound along with MT and PR. The aim of this study was to develop a reversed phase high-performance liquid chromatography (RP-HPLC) method with UV-detection for the simultaneous determination of atenolol (ATN), MT, and PR in the perfusion medium used in SPIP experiments. Separation of compounds were performed using an InertSustain C18 (250 × 4.6 mm, 5 µm) HPLC column at 35 °C. The mobile phase was a mixture of acetonitrile and phosphate buffer (pH 7.0, 12.5 mM) in gradient elution, and was delivered at a flow rate of 1 mL/min. The acetonitrile ratio of the mobile phase increased linearly from 10 to 35 % over 15 min. The injection volume was 20 µL, and ATN, MT and PR were detected at 224 nm. The retention times under optimum HPLC conditions were 5.028 min, 12.401 min, and 13.507 min for ATN, MT and PR, respectively. The developed RP-HPLC method was validated for selectivity, specificity, calibration curve and range, accuracy and precision, carry-over effect, stability, reinjection reproducibility, recovery and robustness. The method was linear for ATN (0.76-50 μg/mL), MT (1.14-50 μg/mL), and PR (0.47-20 μg/mL) with determination coefficients of 0.9999, 0.9994 and 0.9998, respectively. The results obtained for all validation parameters of the developed RP-HPLC method met the required limits of the ICH M10 Guideline., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Clinical practice guidelines advise against crushing modified-release dosage forms. Metoprolol succinate modified-release (MS-MR) tablets are commonly crushed in clinical practice to facilitate administration to patients with swallowing difficulties or using feeding tubes. To date, the effect of this practice remains unexplored. The in vitro effects of crushing commercially available MS-MR tablets were explored using a holistic approach., Methods: Dissolution profiles of crushed versus whole MS-MR tablets were compared. Tablets were crushed to powder state using pragmatic method mimicking hospital practices. For standardization purposes, the same operator, duration (60 seconds), hand, and mortar-pestle apparatus were used. Dissolution studies were conducted per U.S. Pharmacopeia at pH 1.2, pH 4.5, and pH 6.8 with USP apparatus 2 (paddle) at rotation speed of 50 rpm at 37±0.5 °C in 500 mL dissolution media. Samples were withdrawn at predetermined time points. Percent drug dissolved was measured by validated UV-vis Spectrophotometry. Comprehensive analysis of the dissolution data was conducted using model-independent, model-dependent, and ANOVA-based approaches (SPSS v.23 at α=0.05). Similarity (f 2 ) and difference (f 1 ) factors were calculated to compare the dissolution profiles between crushed (CT) and whole tablets (WT). Goodness of fit (GOF) analysis examined the compliance between in vitro dissolution behaviors and several drug release models. Model selection was based on GOF plots, Akaike criteria and adjusted coefficient of determination (R 2 adj ). Imaging and particle size distribution analysis were conducted to examine associated surface and morphologic changes., Results: The dissolution profiles were not similar at pH 4.5 (f 2 =45.43, f 1 =18.97) and pH 6.8 (f 2 =31.47, f 1 =32.94). CT best fitted with Higuchi (pH 1.2: R 2 adj =0.9990), Weibull (pH 4.5: R 2 adj =0.9884), and Korsmeyer-Peppas (pH 6.8: R 2 adj =0.9719). Contrastingly, WT best fitted with Hopfenberg (pH 1.2: R 2 adj =0.9986), logistic (pH 4.5: R 2 adj =0.9839) and first-order (pH 6.8: R 2 adj =0.9979) models. A significant difference in the dissolution profiles was found between CT and WT using multivariate analysis of variance per time points and between the tablet forms (p=0.004). This was confirmed by unparalleled dissolution profiles. Crushing resulted in variations in particle size and surface morphological changes to the micropellets., Conclusion: Crushing practices change the dissolution profile of MS-MR tablets by deforming the surface morphology of embedded micropellets. Amounts of drug dissolved between CT and WT were not the same at the compared time points across gastrointestinal pH ranges. This suggests potential clinical impact on plasma-concentration profiles of critically ill patients using feeding tube., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Cardioselective β-adrenergic blocker metoprolol tartrate, is used in the treatment of different diseases such as cardiac arrhythmias, hypertension, heart failure, angina pectoris, migraine, and hyperthyroidism. Beside dosage forms of the parenteral ampoule and conventional tablets of different manufacturers, there are extended release tablets of metoprolol tartrate in the Turkish Drug Market. In this research work, comparative quality control studies of metoprolol tartrate extended release tablets (original and generic) produced by two different pharmaceutical companies in the Turkey were carried out and evaluated according to the related guidelines. Thickness and diameter, hardness, weight variation, friability, content uniformity and dissolution rate were examined as quality control parameters. A new validated HPLC method for the quantification of metoprolol tartrate has been developed. An ACE column (C18, 5 μm, 250x4.6 mm) and acetonitrile:phosphate buffer (30:70, v/v) mobile phase were used for the determination of metoprolol tartrate. The tablets showed extended release for 8 hours (70.74% release from drug A, 76.87% from the drug B). Both products have acceptable hardness, friability and weight variation values. Content of the active ingredient of the tablets was consistent with label claim (99.45% for drug A and 96.45% for drug B). The dissolution data were evaluated by model dependent and model independent methods using DDSolver program. The obtained results showed that release kinetics of both drugs were well fitted with the Korsmeyer-Peppas model. [ABSTRACT FROM AUTHOR]