Characterization of degradation products of macitentan under various stress conditions using liquid chromatography/mass spectrometry.

Stress testing of a drug candidate is an important step in the drug discovery and development process. The presence of degradation products in a drug affects the quality as well as the safety and efficacy of drug formulation. Hence, it is essential to develop an efficient analytical method which could be useful for the separation, identification and characterization of all possible degradation products (DPs) of a drug. Macitentan (MT) is an endothelin receptor antagonist (ERA) drug used to treat high blood pressure in the lungs. Comprehensive stress testing of MT was carried out as per ICH guidelines to understand the degradation profile of the drug. MT was subjected to various stress conditions such as acidic, basic, neutral hydrolysis, oxidation, photolysis and thermal conditions; and the resulting degradation products were investigated using liquid chromatography/diode-array detection/electrospray ionization high-resolution mass spectrometry (LC/DAD/ESI-HRMS) and tandem mass spectrometry (MS/MS) techniques. An efficient and simple ultra-high-performance liquid chromatography (UHPLC) method has been developed using an Accucore C18 column (4.6 × 150 mm, 2.6 μm) using a gradient elution of 5 mM ammonium formate and acetonitrile as mobile phases. MT was found to degrade under acid and base hydrolysis stress conditions; whereas it was stable under oxidation, neutral hydrolysis, thermal and photolytic conditions. MT formed nine DPs (DP1 to DP9) and one DP (DP10) under acidic and basic hydrolytic conditions, respectively. All the degradation products (DP1 to DP10) were identified and characterized by LC/MS/MS in positive ion mode with accurate mass measurements. MT was found to be labile under hydrolytic conditions. The structures of the DPs were characterized by appropriate mechanisms. The proposed method can be effectively used for the characterization of MT and its DPs.

Yerra NV ，Pallerla P ，Pandeti S ，Tabet JC ，Thota JR ... -  《-》

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 stress degradation products of iloperidone using liquid chromatography coupled with an Orbitrap mass spectrometer.

Iloperidone (ILOP) is an atypical antipsychotic drug used for the treatment of schizophrenia and related psychotic disorders. Comprehensive stress testing of the ILOP drug was carried out as per ICH guidelines to understand its degradation profile. The presence of degradation products in a drug affects not only the quality, but also the safety and efficacy of drug formulation. Thus, it is essential to develop an efficient analytical method which can be useful for the separation, identification and characterization of all possible degradation products of ILOP. ILOP was subjected to various stress conditions such as acidic, basic, neutral hydrolysis, oxidation, photolysis and thermal conditions; and the resulting degradation products were investigated using LC-PDA-HRMS and MS/MS. An efficient and simple ultra-high-performance liquid chromatography (UHPLC) method has been developed on Acquity UPLC® BEH C18 column (2.1 × 100mm, 1.7 μm) using a gradient elution of heptafluorobutyric acid (0.1% HFBA) and acetonitrile as mobile phase. ILOP was found to degrade under acidic and basic hydrolysis and oxidative stress conditions, whereas it was stable under neutral hydrolysis, thermal and photolytic conditions. A total of seven degradation products (DP1 to DP7) were identified and characterized by LC/MS/MS in positive ion mode with accurate mass measurements. The hydrolytic degradation under acidic and basic conditions produced two DPs (DP1 and DP2) and four DPs (DP4 to DP7), respectively, whereas DP3 was formed under oxidative conditions. In silico toxicity predictions showed higher probability values for DP4, DP6 and DP7, which indicates these DPs have the potential to mutate DNA. ILOP was found to be labile under hydrolytic and oxidative conditions. The structures of the degradation products were rationalized by appropriate mechanisms. The proposed method can be effectively used for the determination and detection of ILOP and its degradation products.

Pandeti S ，Rout TK ，Tadigoppula N ，Thota JR ... -  《-》

Structural characterization of alkaline and oxidative stressed degradation products of lurasidone using LC/ESI/QTOF/MS/MS.

A selective, accurate, precise and robust stability indicating liquid chromatography assay method was developed for the monitoring of a novel antipsychotic drug, lurasidone, in the presence of its degradation products (DPs). Also, we investigated degradation behavior of the drug under various stressed conditions such as hydrolytic (acidic, basic and neutral), oxidation, photolytic and thermal. The drug was found to be degraded under base hydrolytic and oxidative conditions, while it was stable in acid and neutral hydrolytic, photolytic and thermal conditions. The method showed adequate separation of lurasidone and its DPs on Xterra C18 (150 mm × 4.6 mm i.d., 3.5 μm) column using 20 mM ammonium formate (pH 3.0): acetonitrile as a mobile phase in gradient elution mode at a flow rate of 0.6 mL/min. This method was extended to liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI/QTOF/MS/MS) for structural characterization of DPs. A total of five DPs were characterized by LC/ESI/QTOF/MS/MS studies. Most probable mechanisms for the formation of DPs were proposed. The developed method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonization Guideline Q2 (R1).

Kumar Talluri MVN ，Dharavath S ，Kalariya PD ，Prasanth B ，Srinivas R ... -  《-》

Validated stability indicating assay method of olaparib: LC-ESI-Q-TOF-MS/MS and NMR studies for characterization of its new hydrolytic and oxidative forced degradation products.

Olaparib (OLA) is a poly ADP ribose polymerase (PARP) enzyme inhibitor used to treat prostate, ovarian and breast cancer. The drug substance OLA was subjected to forced degradation as per ICH prescribed guidelines. It was degraded in hydrolytic (acidic and basic) and oxidative stress conditions and yielded four degradation products (DPs) while it remained stable in neutral hydrolytic, dry heat and photolytic stress conditions. A stability indicating assay method was developed to separate OLA and its DPs using InertSustain C18 column (250 × 4.6 mm, 5 μm) with a gradient mobile phase of 10 mM ammonium acetate (pH 4.5) and acetonitrile (ACN) at a flow rate of 1 mL min-1. The characterization of DPs was carried out by using liquid chromatography-electrospray ionization-quadrupole-time of flight tandem mass spectrometry (LC-ESI-Q-TOF-MS/MS). Major degradation products (DP-1 and DP-2) were isolated by using preparative HPLC and structures were further confirmed by using NMR spectroscopy. All the obtained DPs were new and not reported previously. The developed chromatographic method was validated as per ICH Q2 (R1) guideline and USP general chapter on method validation.

Thummar M ，Kuswah BS ，Samanthula G ，Bulbake U ，Gour J ，Khan W ... -  《-》