Hydrolytic Stress Conditions Research Articles

A comprehensive study on the identification and characterization of major degradation products of synthetic liraglutide using liquid chromatography-high resolution mass spectrometry.

Liraglutide (LGT) is a synthetic glucagon-like peptide-1 analogue mainly used for the treatment of type-2 diabetes or obesity. Comprehensive stability testing is essential in the development and routine quality control of synthetic therapeutic peptide pharmaceuticals. The GLP-1 peptide drugs are usually formulated in aqueous-base solution, which can generate stability issues during manufacturing, storage or shipment. The current study endeavors to observe the chemical stability behavior of LGT by exposing the drug substance to oxidative and hydrolytic stress conditions. A simple liquid chromatography (LC) method was developed where sufficient resolution between LGT and the generated degradation products was achieved. In total, 19 degradation products (DPs) were separated under acidic, basic and oxidative stress conditions. Using LC-HRMS, MS/MS studies, the generated degradation products were identified and characterized. The mechanistic fragmentation pathway for all generated DPs were established and the plausible chemical structure for the identified DPs was predicted based on MS/MS data. The results strongly suggest that LGT is highly susceptible to degrade under oxidative and hydrolytic conditions. Furthermore, this study provides insights into the hydrolytic and oxidative stability of LGT, which can be implied during generic and novel formulation drug development and discovery in synthesizing relatively stable GLP-1 analogues.

A comprehensive study on the identification and characterization of degradation products of lipoglycopeptide Dalbavancin using LC and LC-HRMS/MS.

Dalbavancin is the second-generation approved semisynthetic lipoglycopeptide by the United States Food and Drug Administration (USFDA) for the treatment of acute bacterial skin and skin-structure infections. Unlike other lipoglycopeptides, the stability behavior of Dalbavancin was least explored, which is a prerequisite. The current study endeavors to elucidate the oxidative and hydrolytic stability behavior of Dalbavancin by exposing the drug to oxidative, acidic, and basic stress conditions. A simple liquid chromatography (LC) method was developed, where significant resolution between Dalbavancin, its homologs, and the generated degradation products was achieved. Seven degradation products were identified under acidic, basic, and oxidative stress conditions. Using liquid chromatography and high-resolution mass spectrometry (LC-HRMS), MS/MS studies, the generated degradation products were identified and characterized. Formation of isomeric degradation products was identified especially upon exposure to basic stress conditions. The mechanistic fragmentation pathway for the seven degradation products was established, and the chemical structure for the identified degradation products was elucidated. The results strongly suggest that Dalbavancin is highly susceptible to degradation under oxidative and hydrolytic stress conditions. This study provides insights into the hydrolytic and oxidative stability of Dalbavancin, which can be employed during drug development and discovery in synthesizing relatively stable analogs.

Discerning the stability behaviour of mavacamten availing liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy: In silico toxicity and mutagenicity prediction of degradation products.

The present study aimed to separate, identify, and characterise the degradation products formed when mavacamten is exposed to stress degradation as well as the stability of the drug in various environments and also to understand its degradation chemistry. Prediction of in silico toxicity and mutagenicity was aimed at the observed degradation products. Stress degradation along with stability studies and degradation kinetics were performed on mavacamten, and separation of degradation products was carried out by high-performance liquid chromatography. Tandem mass spectrometry studies were executed to characterise the structures of degradation products using product ion fragments. Orthogonally, nuclear magnetic resonance experiments were conducted to elucidate the structures having ambiguity in characterising them. Deductive Estimation of Risk from Existing Knowledge and Structure Activity Relationship Analysis using Hypotheses software were used to establish in silico toxicity and mutagenic profiles of mavacamten and its degradation products. Two degradation products of mavacamten found in acidic hydrolytic stress conditions were separated, identified, characterised, and proposed as 1-isopropylpyrimidine-2,4,6(1H,3H,5H)-trione and 1-phenylethanamine. Mavacamten was found to be stable under different pH and gastrointestinal conditions. The degradation kinetics of mavacamten under 1 N acidic condition followed zero-order kinetics, and it was degraded completely within 6 h. In silico toxicity and mutagenicity studies revealed that 1-phenylethanamine can be a skin sensitiser. A high-performance liquid chromatography method was developed for the separation of degradation products of mavacamten and characterised by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance. During the manufacturing and storage of drug product, precautions need to be taken when dealing with acidic solutions as the drug is prone to hydrolysis in acidic conditions. The formation of 1-phenylethanamine under these conditions is to be monitored as it is a skin sensitiser.

STABILITY INDICATING UPLC METHOD FOR ESTIMATION OF BENAZEPRIL AND HYDROCHLOROTHIAZIDE IN BULK AND COMBINED DOSAGE FORM

Objective: The main objective was to develop stability indicating UPLC technique for simultaneous estimation of Benazepril and Hydrochlorothiazide in bulk and formulation. Methods: 0.1% Triethylamine phosphate: Methanol (25:75v/v) was used as the mobile phase. Benazepril linearity was found to be 4-20 µg/ml and Hydrochlorothiazide linearity was found to be 5-25 g/ml. The detection wavelength was 236 nm, and the retention period of Benazepril was 3.4 min and Hydrochlorothiazide was 5.4 min with a flow rate of 1.0 ml/min. According to the ICH guidlines, the proposed method was validated and stress studies revealed that the drugs are prone to alkali and peroxide stress conditions. Results: The calibration curve was plotted, and the regression equations for Benazepril were y = 2,01,491.67x+60,532.30 with a correlation coefficient (r2) of 0.9997 and Hydrochlorothiazide were y = 64,635.86x-74,607.10 with a correlation coefficient (r2) of 0.9994. According to the accuracy research, the percent recovery of Benazepril is 99.09-100.69 % and that of Hydrochlorothiazide is 98.27-101.88%, both of which are within the ICH recommendations. Benazepril has a limit of detection of 0.08 g/ml-0.24 g/ml and Hydrochlorothiazide has a limit of quantitation of 0.03 g/ml-0.10 g/ml. The procedure was found to be straightforward, linear, rapid, exact, repeatable, and robust. It was determined that the % RSD was within ICH norms. Stress degradation tests showed the drug's vulnerability to oxidative, thermal, photolytic, acid, basic, and neutral hydrolysis stress conditions. Under the circumstances of alkali and peroxide stress, it was discovered that the drug degraded most quickly. Conclusion: The developed chromatographic technique under consideration was suitable for the accurate, precise, and quick simultaneous measurement of hydrochlorothiazide and benazepril in both their bulk and medicinal dose forms.

Stability Indicating HPTLC Method Development and Validation for Acebrophylline in Bulk and its Tablet Dosage Form

A simple, precise, accurate stability-indicating method was developed and validated for Acebrophylline in bulk and tablet dosage form. The chromatographic separation was achieved by using Methanol: Acetonitrile: Acetone: Formic acid (4:4:2:0.1 v/v/v/v) as mobile phase and UV detection at 272nm. The retention factor for Acebrophylline was found to be 0.74±0.10. The developed method was validated with respect to linearity, accuracy, precision, limit of detection, limit of quantitation, and robustness as per ICH guidelines. Results were found to be linear in the concentration range of 400-2400ng band -1 with a correlation coefficient of 0.9921. The % assay was found to be 102.4±5. The drug was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis, and thermal degradation. The developed method can be used for the quantification of drug in the dosage form, bulk drug as well as for routine analysis in quality control laboratories.

Multivariate Chemometric Comparison of Forced Degradation and Electrochemical Oxidation LC-MS Profiles of Maraviroc.

In this study, nine forced degradation products of maraviroc were found using chemometric analysis. This antiretroviral drug was subjected to photolytic, oxidative, as well as neutral, basic and acidic hydrolysis stress conditions. Additionally, its electrochemical transformation on platinum, gold and glassy carbon screen-printed electrodes was examined. This study showed that maraviroc is especially susceptible to UVA, H2O2 and electrochemical degradation, while being resistant to neutral and acidic hydrolysis. A cluster analysis showed that the electrochemical transformation, with particular reference to the platinum electrode, is able to partially simulate the forced degradation processes, especially in the context of redox reactions. These findings indicate that the electrochemical methods can be considered as quick and relatively low-cost supplements to the commonly applied forced degradation procedures.

Development and Validation of stability indicating RP-HPLC method for the estimation of Ertugliflozin by forced degradation studies

Background: From the literature survey it was found that stability indicating analytical methods have not been reported for evaluation of Ertugliflozin in drug substance (bulk or API) and on drug product. Objective: Developing and validating stability indicating RP-HPLC analytical method for the estimation of Ertugliflozin. Method: Current study develops a novel analytical method for separating drug from the degradation products that is formed under stress conditionsby utilizing methanol: water as mobile phase in the composition of 90:10 v/v using HiQ Sil C-18 (150×4.6)mm, 5.0µm column usingUV detection at 260 nm and flow rate of 0.7 mL/min. Results: Retention time for Ertugliflozin was observed to be 4.1 min. Ertugliflozin was exposed to stress conditions of hydrolysis (acid and alkali degradation), oxidation, photolysis and neutral decomposition. The developed method was validated taking into reference ICH guidelines. Conclusion: This method can be used routinely in pharmaceutical industries to analyse drugs in pharmaceutical dosage forms.

Stability Indicating RP-HPLC Method Development and Validation for the Estimation of Ondansetron in Bulk and their Pharmaceutical Dosage Form

A simple, rapid, precise and accurate stability indicating RP-HPLC method was developed and validated for the estimation of Ondansetron in bulk drug and pharmaceutical dosage form. A Phenomenex C18 (150 mm × 4.6 mm I.D., 5 µm particle size) column was used as stationary phase with mobile phase consisting of 0.1% Formic acid (pH 4.25):Acetonitrile in the ratio of 50:50 V/V. The flow rate was maintained at 0.6 mL/min and effluents was monitored at 250 nm. The retention time was 2.91 min. The linearity of the method was observed in the concentration range of 5-25 µg/mL with correlation coefficient of 0.999. The method developed was validated for linearity, precision, accuracy, system suitability and forced degradation studies like acidic, alkaline, oxidative and hydrolytic stress conditions were performed as per ICH guidelines. The results obtained in the study were within the acceptable limits and hence this method can be used for the estimation of Ondansetron in pure drug and pharmaceutical dosage form.

Force degradation studies of relugolix: identification, isolation and structure characterization of stress degradation products by using liquid chromatography-mass spectrometry, auto purification mass mediated preparative-high performance liquid chromatography, high resolution mass spectrometry, nuclear magnetic resonance spectroscopy

To assess the stability of Relugolix under stress conditions, identify and characterize the degradation products, it was subjected to hydrolytic and oxidative stress conditions, according to the International Council for Harmonization guideline Q1A (R2). The drug showed degradation in basic and oxidative conditions, while it was stable in acid conditions. Four degradation products were obtained, two from each basic and oxidative degradation, which was separated on a C18 column by using Auto Purification Mass Spectrometer. The four degradant products have not been reported earlier in any of the literature and are being reported here for the first time. HIGHLIGHTS Present work captures force degradation of Relugolix under acidic, basic, oxidative, photolytic, and thermal conditions as per International Council for Harmonization guidelines. Two degradation products were observed in basic condition marked as Degradation Product-1, Degradation Product-2 and two degradation products were formed in oxidative condition marked as Degradation Product-3, Degradation Product-4. All the four degradants are novel and are not published in any of the literature. Four degradation products were identified and characterized using various high-end analytical techniques such as Liquid Chromatography and Mass Spectrometer, Reversed Phase–High Performance Liquid Chromatography, High Resolution Mass Spectrometer and Nuclear Magnetic Resonance spectroscopy.

STABILITY INDICATING HPLC METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF EMTRICITABINE, DOLUTEGRAVIR AND TENOFOVIR ALAFENAMIDE IN THEIR COMBINED PHARMACEUTICAL DOSAGE FORM

A simple, rapid, precise and accurate reversed phase HPLC stability indicating method was developed for simultaneous determination of emtricitabine (ECT), dolutegravir (DOL) and tenofovir alafenamide (TEN) in their combined dosage marketed formulation. The chromatographic separation was achieved on Hypersil BDS C18 (250  4.6 mm, 5.0 µ) column using 0.5 M potassium dihydrogen phosphate buffer: acetonitrile (80: 20, v/v), pH 3.5 ± 0.1 maintained by 0.1 % o-phosphoric acid as mobile phase at a flow rate of 1.0 mL/min and monitored at 260 nm. All three analytes were resolved at retention times of 5.777, 6.783, 8.393 min for ECT, DOL, and TEN respectively. The assay performance of the present developed method was validated for various parameters like system suitability, linearity, accuracy, precision, robustness, limit of detection and quantification. The calibration curves were linear over concentration ranges of 12.5-75.0, 50.0-300, and 6.25-37.5 μg/ml for DOL, ECT, and TEN, respectively with correlation coefficients  0.9995. All three analytes were subjected to various stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found in alkaline condition. The present method demonstrated to be effective stability-indicating by resolution of the analytes from their forced-degradation products. The validated method was successfully applied for the simultaneous estimation three drugs in their combined pharmaceutical dosage form Spegra.

A Stability-Indicating Ultra Performance Liquid Chromato-Graphic (UPLC) Method for the Determination of a Mycophenolic Acid-Curcumin Conjugate and Its Applications to Chemical Kinetic Studies.

A simple, precise, and accurate reversed-phase ultra-performance liquid chromatographic (UPLC) method was developed and validated for the determination of a mycophenolic acid-curcumin (MPA-CUR) conjugate in buffer solutions. Chromatographic separation was performed on a C18 column (2.1 × 50 mm id, 1.7 µm) with a gradient elution system of water and acetonitrile, each containing 0.1% formic acid, at a flow rate of 0.6 mL/min. The column temperature was controlled at 33 °C. The compounds were detected simultaneously at the maximum wavelengths of mycophenolic acid (MPA), 254 nm, and curcumin (CUR), or MPA-CUR, at 420 nm. The developed method was validated according to the ICH Q2(R1) guidelines. The linear calibration curves of the assay ranged from 0.10 to 25 μg/mL (r2 ≥ 0.995, 1/x2 weighting factor), with a limit of detection and a limit of quantitation of 0.04 and 0.10 μg/mL, respectively. The accuracy and precision of the developed method were 98.4–101.6%, with %CV < 2.53%. The main impurities from the specificity test were found to be MPA and CUR. Other validation parameters, including robustness and solution stability, were acceptable under the validation criteria. Forced degradation studies were conducted under hydrolytic (acidic and alkaline), oxidative, thermal, and photolytic stress conditions. MPA-CUR was well separated from MPA, CUR, and other unknown degradation products. The validated method was successfully applied in chemical kinetic studies of MPA-CUR in different buffer solutions.

Establishment of validated stability indicating purity method based on the stress degradation behavior of gonadotropin-releasing hormone antagonist (ganirelix) in an injectable formulation using HPLC and LC-MS-QTOF.

Stress study of a drug substance or pharmaceutical drug product provides a vision into degradation pathways and degradation products of the active pharmaceutical ingredient and helps in interpretation of the chemical structure of the degradation impurities. In the current study, Ganirelix active ingredient presented in the Orgalutran® was stressed with acidic and alkali hydrolysis, photolysis, thermal and oxidation conditions as per the guidelines of International Conference on Harmonization (ICH) Q1A (R2). Ganirelix was found to be labile under thermal and alkali hydrolytic stress conditions, while it was stable to acid hydrolytic, oxidative and photolytic stress. All degradation products were separated with a resolution > 1.5 on a C18 column (2.6 µm, 25 cm×4.6 mm) using a hydrophilic ion pair such as sodium perchlorate, at a concentration <0.04 M. In total, four major degradant impurities were found during stress study. These impurities were fractionated and desalted by flash chromatography for identification of chemical structures. LC-MS-QTOF analysis revealed that two degradation products are diastereomers of Ganirelix, one degradation product is a deamination compound and other degradation product result from the insertion of a new amino acid residue in the Ganirelix peptide sequence. The developed method is sensitive enough to quantify the related substances of Ganirelix at the 0.04% level with that of Ganirelix test concentration.

Optimization and Validation of Rp-Hplc Stability-Indicating Method for Determination of Efavirenz and its Degradation Products

Stability is considered one of the most important criteria in pharmaceutical quality control. With this objective a stability-indicating high performance liquid chromatographic (HPLC) method has been established for analysis of Efavirenz in the presence of the degradation products generated in the stress degradation study. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal decomposition. Extensive degradation was found to occur in alkaline medium and under thermal stress. Minimum degradation was observed under acidic medium, in the photolytic conditions and oxidative stress. Successful separation of drug from degradation products formed under stress conditions was achieved on a C-8 column using acetonitrile: potassium dihydrogen phosphate (pH 2.9, 25mM) - (60:40% v/v) as the mobile phase. The flow rate was 1 mL min -1 and the detector was set at in a range of wavelength be- tween 220nm to 390nm. The method was validated for linearity, range, precision, accuracy, limit of quantification and limit of detection. Because the method effectively separates the drugs from their degradation products, it can be used as stability-indicating method.

Degradation Studies of Lacidipine: Identification, Isolation and Structural Characterization of Stress Degradation Products using LCMS, Mass mediated Prep-HPLC, NMR and HRMS

The stability of lacidipine drug under stress conditions and the identification of the degradation products, according to ICH guidelines Q1A (R2) were investigated in the hydrolytic and oxidative stress conditions. The drug degradation occurred under hydrolytic conditions like (acidic and basic) while it was stable in the oxidative condition. Three degradation products were formed under acidic condition and one degradation product was formed under basic condition, which was separated by using APMS (Auto Purification Mass Spectrometer) and gradient elution with C18 column. The four degradants have not been characterized earlier and in the present study all the structures were established and characterized using NMR spectroscopy (1D and 2D) and HRMS (high resolution mass spectrometer).

Identification and characterization of forced degradation products of vortioxetine by LC/MS/MS and NMR

Vortioxetine (VTX) is a novel multimodal antidepressant drug that affects the serotoninergic and noradrenergic systems. In this work, the forced degradation of VTX was studied according to (ICH) Q1A (R2) guidelines. The study revealed that VTX was stable under thermal stress conditions and hydrolytic stress conditions i.e., acidic, basic and neutral conditions. In contrast, six degradation products (DPs) were formed under photolytic and oxidative stress conditions. The DPs were identified and characterized by high-resolution LC/MS and LC/MS/MS. The structures of major DPs were further confirmed by the synthesis and characterization by 1H and 13C NMR data. A possible mechanism for the formation of the VTX DPs via photolytic/oxidative stress degradation pathway was proposed.

A stability indicating method development and validation for separation of process related impurities and characterization of unknown impurities of tyrosine kinase inhibitor Nilotinib by RP-HPLC, NMR spectroscopy and ESI-MS

A selective RP-HPLC method for separation and determination of potential related impurities (process related, and degradants) of Nilotinib (NTB) drug substance has been developed and validated. The separation was accomplished on YMC Triart C-18 (150 × 4.6 mm, 3.0 µm) column connected to a photodiode array (PDA) detector using 10 mM NH 4 H 2 PO 4 (pH: 3.5 ± 0.05 adjusted with diluted Ortho phosphoric acid) as a buffer and acetonitrile in a ratio of 85:15 (%v/v) respectively as mobile phase-A, and 10 mM NH 4 H 2 PO 4 buffer, acetonitrile and methanol in a ratio of 20:27.5:52.5 (%v/v/v) respectively as mobile phase B, under gradient elution. The flow rate and column oven temperature were 1.0 mL/min and 50 °C respectively. Detection was carried out at 230 nm. NTB was stressed to degrade under various stress conditions of photolysis, thermal, hydrolysis and oxidation stress as per ICH Q1A (R2). The drug was highly susceptible to acidic and alkaline hydrolytic stress conditions. The drug degraded to two degradation products (DPs), while the remains stable under thermal, photolytic, neutral hydrolytic and oxidative stress conditions. Characterization of DPs was performed by 1 D and 2 D NMR, FT-IR and LC/MS/MS. Optimized method was validated in agreement with ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, robustness and ruggedness. This optimized method can be used for quality control of both drug substance and drug product of NTB.

Study on forced degradation behaviour of dofetilide by LC-PDA and Q-TOF/MS/MS: Mechanistic explanations of hydrolytic, oxidative and photocatalytic rearrangement of degradation products

A solution and solid state forced decomposition study was carried on dofetilide under diverse stress conditions of hydrolysis, oxidation, photolysis and thermal as per International Council for Harmonisation guidelines (ICH) Q1A(R2) to understand its degradation behaviour. A total of eight degradation products (DPs) were identified and separated on reversed phase kromasil 100 C8 column (4.6 mm x 250 mm x5 μm) using gradient elution with ammonium acetate (10 mM, pH 6.2) and acetonitrile as mobile phase. The detection wavelength was selected as 230 nm. The high performance liquid chromatography (HPLC) study found that the drug was susceptible to hydrolytic stress condition, but it was highly unstable to photolytic and oxidative conditions. The solid drug was stable in thermal and photolytic conditions. Initially comprehensive mass fragmentation pattern of the drug was accomplished with the LC/ESI/QTOF/MS/MS studies in positive ionization mode. The same was followed for all the eight degradation products to characterise their structure. The DP4 was N-oxide and the structure was confirmed by LC/APCI/QTOF/MS/MS in positive ionization mode. The complete mass fragmentation pattern of the drug and its DPs were established which in turn helped the characterisation of their structures. The mechanistic pathway for the formation of all the DPs was explained.

Preparation and Characterization of Four Major Novel Degradation Products of Pralatrexate Injection and Validation of HPLC-UV Method

Background: Four major degradation products (1-4) of pralatrexate injection were formed under hydrolytic and light stress conditions. The impurities 1 and 2 were the potential photo degradation products and the impurities 3 and 4 were the potential hydrolytic degradation products. Objective: To prepare and characterize the novel degradation impurities 1, 2, 3 and 4 of pralatrexate injection using NMR, HR MS and IR techniques; and to develop and validate stability indicating analytical reverse phase HPLC-UV method for quantitative simultaneous determination of potential degradation impurities, related substances of pralatrexate and pralatrexate active in pralatrexate liquid formulation. Methods: Gradient HPLC-UV method was developed for the quantification of degradation impurities, related substances and pralatrexate in pralatrexate injection. The separation was achieved on C18 column (250 mm X 4.6 mm, 5µm) using a mobile phase composed of sodium dihydrogen phosphate monohydrate in water (pH 3.0; 0.01M) and methanol. The components were monitored by the UVvisible detector at 242 nm with a flow rate of 1.0 mL/min. Results: The method validation parameters such as accuracy, selectivity, linearity, LOD, LOQ, precision, ruggedness and robustness were demonstrated successfully for pralatrexate and its degradation impurities. The stability-indicating capability of the developed HPLC method was demonstrated by adequate separation of all potential pralatrexate related substances from pralatrexate stressed drug product samples. Conclusion: The developed stability indicating HPLC method was found to be suitable for the simultaneous quantitative determination of potential degradation impurities and related substances of pralatrexate and pralatrexate active in pralatrexate liquid formulation.

Comprehensive stability-indicating high-performance liquid chromatography coupled with diode array detection method for simultaneous determination of amprolium hydrochloride and ethopabate in powder dosage form for veterinary use.

This research deals with the development of a stability-indicating high-performance liquid chromatography method for simultaneous determination of amprolium hydrochloride and ethopabate. To the best of our knowledge, no comprehensive stability-indicating method has been reported for analysis of this mixture. Separation was achieved using Kromasil cyano column with gradient elution of the mobile phase composed of sodium hexane sulfonate solution and methanol. Quantification was based on measuring peak areas at 266nm. Amprolium and ethopabate peaks eluted at retention times 10.42 and 18.53min, respectively. The proposed procedure was validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Linearity ranges for amprolium and ethopabate were 1.5-240 and 1-160μg/mL, respectively. Analytes were subjected to stress conditions of hydrolysis, oxidation and thermal degradation. The proposed method enabled resolution of drugs from their forced-degradation products and amprolium related substance (2-picoline). Moreover, specificity was verified by resolution of the analytes from about 22 drugs used in antimicrobial veterinary products. The validated method was successfully applied to assay of the combined veterinary powder dosage form, additionally it was implemented in the accelerated stability study of the dosage form when stored for six months at 40°C and 75% relative humidity.

Development and Validation of LC–MS Method for the Estimation of N-Acetyl-Tryptophan and its Impurities Under Stress Conditions

A highly sensitive and simple high-performance liquid chromatographic–tandem mass spectrometric (LC–MS–MS) assay was developed and validated for the quantification of N-acetyl tryptophan (NAT) in formulations and to identify impurities under different stress conditions. N-acetyl tryptophan was analyzed using a reversed-phase gradient elution after treatment under acidic, basic, oxidative, hydrolytic and thermal stress conditions. Linearity in the calibration curve was obtained at a concentration range of 10–100 µgmL−1 (R2 = 0.9916). The lower limits of detection and quantification were 3.53 and 10.69 µgmL−1. The degradation of NAT was observed maximum under oxidation stress (52.84%) and minimum under thermal stress (10.22%). Three major degradation products were formed under acidic and basic stress conditions, of which tryptophan was the major one. Thermal stress yielded a single major impurity at m/z 230. Water hydrolysis could form dihydroxy-N acetyl tryptophan at m/z 279. Oxidation stress led to the formation of seven major degradation products. The most effective stress condition was found to be oxidative which leads to 52.84% degradation of the drug followed by acidic stress (34.64%) and basic stress (15.66%). The present study showed an accurate, precise and sensitive LC–MS–MS method for the systematic investigation of NAT and its impurities in formulations.