Identification of forced degradation products of tamsulosin using liquid chromatography/electrospray ionization tandem mass spectrometry.

A rapid and gradient high-performance liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of tamsulosin. Tamsulosin, a selective α1-adrenoceptor antagonist, was subjected to forced degradation studies under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per ICH guidelines Q1A (R2). The drug degraded significantly under hydrolytic (base and neutral), thermal, oxidative and photolytic conditions, while it was stable to acid hydrolytic stress conditions. A total of twelve degradation products were formed and the chromatographic separation of the drug and its degradation products were achieved on a GRACE C-18 column (250mm×4.6mm, 5μm). All the degradants have been identified and characterized by LC/ESI-MS/MS and accurate mass measurements. To elucidate the structures of degradation products, fragmentation of the [M+H](+) ions of tamsulosin and its degradation products was studied by using LC-MS/MS experiments combined with accurate mass measurements. The product ions of all the protonated degradation products were compared with the product ions of protonated tamsulosin to assign most probable structures for the observed degradation products.

Namdev D ，Borkar RM ，Raju B ，Kalariya PD ，Rahangdale VT ，Gananadhamu S ，Srinivas R ... -  《-》

Identification and characterization of stressed degradation products of prulifloxacin using LC-ESI-MS/Q-TOF, MSn experiments: development of a validated specific stability-indicating LC-MS method.

A rapid, specific and novel gradient LC-MS method has been developed and validated for the identification and characterization of stressed degradation products (DPs) of prulifloxacin (PF) using liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS). PF was subjected to hydrolytic (acidic, alkaline and neutral), oxidation, photolytic and thermal stress, as per ICH guidelines Q1A (R2). The drug showed extensive degradation in hydrolytic and oxidative, while it was stable to thermal and photolytic stress conditions. In total, 13 DPs were formed and the chromatographic separation of drug and its DPs was achieved on a C-18 column (4.6 × 250 mm, 5 μm) using gradient elution method. All the DPs have been identified and characterized using MS(n) experiments and accurate mass measurements. The LC-MS method was validated with respect to specificity, linearity, accuracy, precision and robustness.

Raju B ，Ramesh M ，Srinivas R ，Raju SS ，Venkateswarlu Y ... -  《-》

Identification and characterization of stressed degradation products of metoprolol using LC/Q-TOF-ESI-MS/MS and MS(n) experiments.

A rapid, specific and reliable isocratic high-performance liquid chromatography combined with quadrupole time-of-flight electrospray ionization tandem mass spectrometry (LC/Q-TOF-ESI-MS/MS) method has been developed and validated for the identification and characterization of stressed degradation products of metoprolol. Metoprolol, an anti-hypertensive drug, was subjected to hydrolysis (acidic, alkaline and neutral), oxidation, photolysis and thermal stress, as per ICH-specified conditions. The drug showed extensive degradation under oxidative and hydrolysis (acid and base) stress conditions. However, it was stable to thermal, neutral and photolysis stress conditions. A total of 14 degradation products were observed and the chromatographic separation of the drug and its degradation products was achieved on a C(18) column (4.6 × 250 mm, 5 µm). To characterize degradation products, initially the mass spectral fragmentation pathway of the drug was established with the help of MS/MS, MS(n) and accurate mass measurements. Similarly, fragmentation pattern and accurate masses of the degradation products were established by subjecting them to LC-MS/QTOF analysis. Structure elucidation of degradation products was achieved by comparing their fragmentation pattern with that of the drug. The degradation products DP(2) (m/z 153) and DP(14) (m/z 236) were matched with impurity B, listed in European Pharmacopoeia and British Pharmacopoeia, and impurity I, respectively. The LC-MS method was validated with respect to specificity, linearity, accuracy and precision.

Borkar RM ，Raju B ，Srinivas R ，Patel P ，Shetty SK ... -  《-》

Liquid chromatography/electrospray ionization tandem mass spectrometry study of repaglinide and its forced degradation products.

Stress stability studies of drugs have been recognized as an essential part of the drug development process. These studies are used to investigate the intrinsic stability of the drugs and for the development of a selective stability indicating assay method (SIAM). Stress testing is also useful for the formulation and packaging development, shelf-life determination and designing of manufacturing processes. As per regulatory guidelines, stress degradation studies and structural characterization should be carried out to establish degradation pathways of the drug, which is essential from both the efficacy and safety point of view. As the stress stability studies of repaglinide have not been reported in the literature, the present study has been undertaken. Repaglinide (RP), an oral anti-diabetic drug, was subjected to hydrolysis (acidic, alkaline and neutral), oxidation, photolysis and thermal stress conditions as per International Conference on Harmonization (ICH) guidelines Q1A (R2). The chromatographic separation of the drug and its degradation products (DPs) was achieved on an Agilent XDB C-18 column using the gradient elution method with a mobile phase consisting of 20 mM ammonium acetate and acetonitrile at flow rate of 1.0 mL min-1 . The DPs were characterized using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) in combination with accurate mass measurements. The drug degraded under hydrolytic and oxidative stress, while it was stable under thermal and photolytic stress conditions. In total, six DPs were formed and the LC/MS method described here can resolve all DPs from the parent as well as from each other under various stress conditions. To elucidate the structures of DPs, fragmentation of the [M + H]+ ions of RP and its DPs was studied by using LC/ESI-MS/MS combined with accurate mass measurements. The forced degradation of RP carried out as per ICH guidelines results in the formation of six degradation products which have been characterized using LC/MS/MS in combination with accurate mass measurements.

Purna Chander C ，Raju B ，Ramesh M ，Shankar G ，Srinivas R ... -  《-》

Identification of hydrolytic and isomeric N-oxide degradants of vilazodone by on line LC-ESI-MS/MS and APCI-MS.

The present study reports the degradation behavior of a new antidepressant drug, vilazodone, under various stress conditions as per International Conference on Harmonization guidelines (ICH, Q1A(R2). The investigation involved monitoring decomposition of the drug under hydrolytic (acidic, basic and neutral), oxidative, photolytic and thermal stress conditions and identifying degradation products. A rapid, precise, accurate and robust ultra high performance liquid chromatography (UPLC) method has been developed on a Waters CSH Phenyl-Hexyl column (100 mm × 2.1 mm, 1.7 μm) using gradient elution of 10mM ammonium acetate buffer (pH 5.0) and acetonitrile as mobile phase. The drug was found to be degraded in hydrolytic (acidic and basic) and oxidative conditions, whereas it was stable under neutral hydrolytic, photolytic and thermal stress conditions. The method was extended to quadrupole time-of-flight mass spectrometry (QTOF-MS) for the structural characterization of degradation products. It has been observed that isomeric N-oxide degradation products were formed under oxidative stress condition. The exact location of N-oxidation in the drug was investigated using atmospheric pressure chemical ionization (APCI) due to the formation of characteristic fragment ions. These fragment ions resulted from Meisenheimer rearrangement owing to thermal energy activation at the vaporizer of APCI source. All degradation products were comprehensively characterized by UPLC-ESI-MS/MS and UPLC-APCI-MS experiments. The most probable mechanisms for the formation of degradation products have also been proposed. The method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per ICH guidelines.

Kalariya PD ，Talluri MV ，Patel PN ，Srinivas R ... -  《-》