Degradation pathways and impurity profiling of the anticancer drug apalutamide by HPLC and LC-MS/MS and separation of impurities using Design of Experiments

Development, evaluation of critical method variables and stability assessment using a Box-Behnken design for the determination of organic impurities in a pharmaceutical dosage form of a centrally acting muscle relaxant drug chlorzoxazone

This study validates a stability-indicating LC method for detecting organic impurities in the chlorzoxazone dosage form. Using a Waters X-Select R HSS T3 analytical column, mobile phase of it was made by mixing of water, methanol, and glacial acetic acid in the ratio of 700:300:10 (v/v/v). The drug product and drug substance were subjected to the stress conditions such as acid, base, oxidation, heat, and photolysis as per the recommendations of the International Conference on Harmonization (Q2) methodology. The study revealed the susceptibility of 4-chloro-2-aminophenol to alkaline environments, emphasizing peak homogeneity and stability. The method verification, per ICH guidelines and USP<1225>, established precision, specificity, linearity, accuracy, and robustness for quality control. The mean impurity recovery ranged from 95.5% to 105.2%, the correlation coefficient (r) was greater than 1.000, and the RSD values (n = 6) ranged from 0.6% to 5.1% across the LOQ-150% ranges. Full-factorial design tested final method conditions, evaluating multiple parameters concurrently. Graphical optimization within the design space defined strong method requirements, ensuring consistent and reliable outcomes. The study develops and validates chlorzoxazone stability-indicating methods, employing advanced statistical approaches like design of experiments and factorial design, with resilient conditions established through graphical optimization of the design space.

Design, Characterization and Biopharmaceutical Applications of Novel Green Boron-Carbon Quantum Dots for Quantification of Apalutamide; Greenness Evaluations

The diagnosis of prostate cancer has been evolving in the current decade, with expected mortality rates of 499,000 death by the year 2030. Apalutamide (APL) has been approved in 2018 as the first drug for the controlling of prostate cancer. APL significant success warrantied its high global sales, which are expected to surpass 58% of segment market sales (together with another drug; enzalutamide). Therefore, new, fast and environmentally friendly analytical methods are required for its determination for the quality control and biological monitoring purposes. The proposed research designs and evaluates the first fluorimetric approach based on novel porous green boron-doped carbon quantum dots (B@CDs) for the determination of APL in biopharmaceutical matrices. The synthetic approach has high quantum yield (31.15%). B@CDs were characterized using several tools, including transmission electron microscopy (TEM), dynamic light scattering (DLS), FTIR and Energy dispersive X-ray spectroscopy (EDX) which proved their improved surface properties with an average nano-diameter of 3.0 nm. The interaction between B@CDs and APL led to enhancement their fluorescence at 441 nm (excitation at 372 nm). The approach was validated for the determination of APL within concentration range of 15.0-700.0 ng mL- 1 with quantification limit LOQ 4.37 ng mL- 1 and detection limit LOD 1.44 ng mL- 1. The approach was successfully applied for the determination of APL in human plasma and pharmaceutical monitoring of its marketed tablet form. Then, the approach was assessed for its environmental impact using different metrics and proved its ecological greenness.

Stability indicating reversed-phase-high-performance liquid chromatography method development and validation for pyridostigmine bromide and sodium benzoate in oral solution

The present study focuses on the development of a simple, rapid, specific, and stability-indicating HPLC method for the simultaneous analysis of pyridostigmine bromide (PGB) and sodium benzoate (SBN) in oral liquid dosage forms. Analytical techniques should enhance sensitivity and specificity for the estimation of pharmaceutical drug products. Stress studies were conducted under various International Conference on Harmonization (ICH) conditions for evaluation. The further optimized HPLC method was validated in accordance with the current ICH guidelines. Chromatographic separation was accomplished using a mobile phase consisting of a 950:50 v/v ratio of perchloric acid buffer and acetonitrile as mobile phase-A, and 100% acetonitrile as mobile phase-B. The flow rate is 1.0 mL/min, and the injection volume is 20 μL. Detection of components was carried out at 220 nm for PGB and 228 nm for SBN. The validated HPLC method demonstrated high specificity, with linearity ranging between 24 and 72 μg/mL for PGB and 5.2-15.6 μg/mL for SBN. The correlation coefficient for both drugs exceeded 0.999. The method demonstrated high accuracy, exceeding 97%. In stress studies, PGB was found to be sensitive to alkaline stress conditions. The results reveal the successful applicability of the current method for the estimation of PGB and SBN in its marketed formulation, which can be reasonably inferred to assess other formulation systems.

Separation and simultaneous estimation of enantiomers and Diastereomers of muscarinic receptor antagonist Solifenacin using stability-indicating Normal-phase HPLC technique with chiral stationary phase amylose tris-(3,5-dimethylphenylcarbamate)

The R,S-enantiomer impurity and diastereomer impurities (S,S-isomer and R,R-isomer) of the solifenacin (S,R-enantiomer) were effectively separated and quantified simultaneously utilizing normal-phase high-performance liquid chromatography with a chiral stationary phase consisting of amylose tris (3,5-dimethylphenylcarbamate) coated on silica-gel (Chiralpak, AD-H). The enantiomeric and stereo-selective separation was achieved within a run time of 35 minutes using a mobile phase of 'n-hexane, ethanol, and diethylamine' in an isocratic elution mode with a detection wavelength of 220 nm. The validation attributes assessed were accuracy (which showed excellent recoveries between 97.5% and 100.4%) and linearity (which was proven in the range of 0.081-1.275 μg.mL-1 , with a linear regression of 0.999). The stress testing experiments proved that the developed methodology by the HPLC technique has stability-indicating characteristics, as all closely eluting peak pairs were separated well with a resolution of 2.3 and without any interference. The proposed methodology was highly efficient in separating and simultaneously determining the chiral impurities (enantiomers and diastereomers) of the solifenacin in the release and stability sample analyses of drug substances and tablets in pharmaceutical formulations.

Separation and quantitative estimation of stereo-selective enantiomers of montelukast in pharmaceutical drug substance and tablets dosage forms by using stability-indicating normal phase-HPLC method

Montelukast sodium (MLS) is a leukotriene receptor antagonist that relieves asthma, bronchospasm, allergic rhinitis, and urticaria. A simple, robust, and stability-indicating normal phase high-performance liquid chromatography method was developed to separate and quantitatively estimate the S-enantiomer of MLS. The chiral separation was achieved using USP L51 packing material along with a mobile phase consisting of a solvent mixture (n-hexane, ethanol, and propionic acid), a flow rate of 1.0 mL/min, a detection wavelength of 284 nm, a column temperature of 30°C and an injection volume of 20 μL. The enantiomers peaks were well separated from the peaks of the placebo, diluting solvent, MLS, and its known impurities with a resolution of more than 2.2 and with no interference. Accuracy and linearity were studied in a range of 0.36-3.597 μg/mL (0.03%-0.30%), with good recoveries between 92.5% and 96.8% and a linear regression coefficient above 0.996. The suggested chiral chromatography method is being considered as an alternative and equivalent method to the United States Pharmacopeia and European Pharmacopeia monographs. The developed method was effectively employed for the study of release and stability samples of MLS. This HPLC method is also capable of separating and estimating the stereo-selective isomers (R- and S-enantiomers) of sulfoxide impurity of MLS in pharmaceutical medicine.

Stability-indicating method development and validation for quantitative estimation of organic impurities of the antidiabetic drug glipizide in drug substance and pharmaceutical dosage form using HPLC

Glipizide is an antidiabetic drug used for the treatment of type 2 diabetes. A simple, reliable and robust reverse-phase liquid chromatographic method (RP-HPLC) was developed and validated as per International Conference on Harmonization Q2(R1) for estimating the impurities of glipizide in pharmaceutical formulations. The chromatographic separation was carried out on a Phenomenex Luna C18 (2), 250 × 4.6 mm, 5 μm with a binary solvent delivery system [MP-A, a homogenous mixture of water and acetonitrile in a ratio of 90:10 (v/v) and 1 ml of orthophosphoric acid; and MP-B, a homogenous mixture of water and acetonitrile in a ratio of 10:90 (v/v) and 1 ml of orthophosphoric acid] with a detection wavelength of 225 nm, a column temperature of 30°C, a flow rate of 1.5 ml/min, and an injection volume of 20 μl. All process, degradant and unknown impurities were separated well with a resolution >2.2 and were estimated accurately without any interference. The recovered values and regression values were 98.7-100.5% and R2  > 0.9999, respectively. The recovery and linearity studies covered the quantitation limit to 150% of the specification limit. The stability-indicating properties of the developed RP-HPLC method was assessed from the forced degradation studies. The developed method was successfully applied for real-time sample analysis of the glipizide dosage form.

Stability-indicating normal-phase HPLC method development for separation and quantitative estimation of S-enantiomer of lacosamide in pharmaceutical drug substance and tablet dosage form

Lacosamide (LA) is an antiepileptic medicine that is used to treat tonic-clonic seizures, partial-onset seizures, mental problems, and pain. A simple, effective, and reliable normal-phase liquid chromatographic technique was developed and validated to separate and estimate the enantiomer of (S-enantiomer) LA in pharmaceutical drug substance and drug product. Normal-phase LC was performed using USP L40 packing material (250 × 4.6 mm, 5 μm) and a mobile phase of n-hexane and ethanol at 1.0 ml min-1 . The detection wavelength, column temperature, and injection volume used were 210 nm, 25°C, and 20 μl, respectively. The enantiomers (LA and S-enantiomer) were completely separated using a minimum resolution of 5.8 and accurately quantified without any interference in a 25-min run time. Accuracy study for stereoselective and enantiomeric purity trials was conducted between 10 and 200%, with recovery values ranging from 99.4 to 103.1% and linear regression values >0.997. The stability-indicating characteristics were assessed using forced degradation tests. The proposed normal-phase HPLC technique is an alternate approach to the official monograph methods (USP and Ph.Eur.) of LA, and it was successfully used in the evaluation of release and stability samples for both tablet dosage forms and pharmaceutical substances.