Simultaneous determination of ivermectin, clorsulon and their related substances in an injectable finished product by a stability-indicating RP-HPLC method

Identification of major degradation products of Clorsulon drug substance including its degradation pathways by high resolution mass spectrometry and NMR

Clorsulon is an effective anthelmintic drug substance extensively used in the treatment of parasitic infestations in both cattle and sheep. An in-depth investigation of Clorsulon's degradation products (DPs) was carried out through forced degradation study to comprehend its degradation path. A total of eight degradation products were separated under various stress degradation conditions. Structural elucidation of these DPs was conducted using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS), and their fragmentation patterns were compared to that of the parent compound. Adequate amount of DP-4 was isolated and purified by semi-preparative high-performance liquid chromatography (HPLC) methods. Subsequently, it was examined in detail using both 1D and 2D NMR (nuclear magnetic resonance spectroscopy). Most probable mechanistic pathways for the formation of degradation products under various stress degradation conditions were proposed to better understand the degradation profile. Based on the results of the stress study, Clorsulon drug substance was found to be unstable under photolytic and oxidative conditions. Understanding Clorsulon's degradation pathway is essential for determining shelf-life prediction of the finished product, safety and efficacy assurance, and guiding the development of stable, high-quality formulations.

Determination of Clorsulon and its related substances in commercial bulk drug substance batches by a rapid ion-pair UPLC method

Clorsulon is a potent anthelmintic agent and is widely used for the treatment and control of parasites including adult liver flukes in cattle and sheep. A rapid ion-paired reversed phase ultraperformance liquid chromatography (IP-UPLC) method has been developed and validated for determination of Clorsulon and its related substances in bulk drug substance batches of Clorsulon with a short octadecyl column. Analytes were eluted by a gradient elution on a Acquity UPLC® BEH C18 column (50 mm × 2.1 mm i.d., 1.7 µm particle size). Column temperature was maintained at 55 °C and all analytes were monitored by UV detection at 268 nm. Mobile phase-A constitutes 3 mM tetrabutylammonium hydroxide in H2O and mobile phase-B constitutes acetonitrile/methanol (50/50, v/v), respectively. All analytes of interest were adequately separated within 5 min. The analytes were quantitated against an external reference standard of Clorsulon. The chemical structures of degradation products of Clorsulon were proposed based on two-dimensional UPLC-MS data. The IP-UPLC method has been successfully validated and demonstrated to be accurate, sensitive, robust, and specific.

Green and Smart Quantitative Quality Control for Veterinary Mixture of Ivermectin and Clorsulon: Ecological Evaluation of Spectral Analyses via Analytical Eco-Scale, Green Analytical Procedure Index, and Analytical GREEnness Metric Approaches

BACKGROUND

The global financial market is still highly threatened by bovine fasciolosis, a parasitic infection that targets cattle, mainly in tropical regions. Binary combination of ivermectin (IVER) and clorsulon (CLO), in challenging concentration ratios, is typically indicated for treatment and control of fasciolosis.

OBJECTIVE

The present study aims at smart simultaneous spectrophotometric assay of both compounds at their high ratio in marketed formulation and synthetic mixtures, without any prior separation. Furthermore, their greenness profile was evaluated and compared with previous reported assay methods, including the official one.

METHODS

Mathematical-based proposed methods are the dual-wavelength, induced dual-wavelength, and first derivative ratio methods. Each is developed, optimized, and applied to determine simultaneously IVER and CLO at linear ranges of 1-30 and 5-40 μg/mL, respectively. They have been validated according to ICH guidelines. Statistical Student t-tests and F-tests compared the proposed methods with a USP chromatographic technique. Ecological appraisal is accomplished using three independent metrics: Analytical Eco-Scale (AES), Green Analytical Procedure Index (GAPI), and Analytical GREEnness Metric Approach (AGREE).

RESULTS

Satisfactory recoveries, ICH compliance, and adherence of proposed methods to the ecological safety margin are achieved.

CONCLUSIONS

Developed methods are eco-friendly and cost-effective and can accomplish a routine quantitative quality control for concurrent determination of both drugs.

HIGHLIGHTS

Veterinary antimicrobials need analytical quality control using safer and green methodologies. Data manipulated spectral analyses of IVER and CLO, in a ratio of 1:10% (v/v), are developed and optimized. AES, GAPI, and AGREE approaches illustrate the high green compliance in respect to assays reported in the literature. Furthermore, the United States Pharmacopeia (USP) assay for IVER and CLO in injectable dosage form depends on analysis of each drug separately in the presence of the other drug, but it cannot determine both drugs simultaneously.

Development and Validation of a Stability-indicating UPLC-DAD Method for the Simultaneous Determination of Ivermectin and Praziquantel in Pharmaceutical Tablets and Dissolution Media

Currently, there is no single rapid and accurate stability-indicating quantitative method that can simultaneously determine both ivermectin and praziquantel and their related compounds. Thus, the goal of this research is to develop and validate a new rapid, accurate, and stability-indicating ultra-performance liquid chromatography (UPLC) method. The method uses a water, acetonitrile, and methanol gradient. The chromatographic separation was achieved on a C18 (1.7 μm, 2.1 × 50 mm) column with a flow rate of 0.7 mL/min, and the column temperature was maintained at 40°C. Analytes are detected at 245 nm. The method was validated in accordance with ICH Q2R1 guidelines. The linearity (R2) was >0.9987 and 0.9997 for praziquantel and ivermectin, respectively. The corresponding accuracy ranged between 98.0 and 102.0%. Intermediate precision (assessed as inter-day precision) was determined by calculating the cumulative %CV of eighteen assay preparations and was less than 2.0% for both praziquantel and ivermectin. The specificity of the method was shown by the resolution of the two active pharmaceutical ingredients (APIs) from any interfering excipients, impurities, or degradation products. The limit of detection and quantitation for ivermectin was 26.80 ng/mL and 81.22 ng/mL, respectively. The limit of detection and quantitation for praziquantel was 1.39 μg/mL and 4.22 μg/mL, respectively. The robustness study proved that method performance is stable against small variations in sample processing parameters (shaking, sonication time, and acetonitrile % in solvent solution) and also against small variations in the initial % of mobile phase components and gradient slope. Using ICH Q2R2 criteria, the method was demonstrated to be specific, accurate, stability indicating, and robust to small variations of chromatographic variables.