Facile Access to Solifenacin Impurity K: One-Step Synthesis and an HPLC-MS Method for Its Determination.

Solifenacin (SFC) is a potent muscarinic antagonist that effectively reduces bladder muscle contraction, thereby alleviating symptoms such as frequency of micturition and urgency. Oxidation of SFC leads to the formation of impurities like Impurity K. Effective analysis and control of this impurity is crucial for ensuring compliance with regulatory standards and safeguarding patient health. To address these challenges, we propose a novel one-step synthesis of Impurity K from SFC. Impurity K was synthesized using cerium(IV) ammonium nitrate (CAN) in water/acetonitrile as the solvent. Additionally, we describe a new HPLC-MS method for the detection of Impurity K in solifenacin succinate tablets.

A Comprehensive Analysis of Fel Ursi and Its Common Adulterants Based on UHPLC-QTOF-MSE and Chemometrics.

BACKGROUND: As one of the four most valuable animal medicines, Fel Ursi, named Xiong Dan (XD) in China, has the effect of clearing heat, calming the liver, and brightening the eyes. However, due to the special source of XD and its high price, other animals' bile is often sold as XD or mixed with XD on the market, seriously affecting its clinical efficacy and consumers' rights and interests. In order to realize identification and adulteration analysis of XD, UHPLC-QTOF-MSE and multivariate statistical analysis were used to explore the differences in XD and six other animals' bile. METHODS: XD, pig gall (Zhu Dan, ZD), cow gall (Niu Dan, ND), rabbit gallbladder (Tu Dan, TD), duck gall (Yan Dan, YD), sheep gall (Yang Dan, YND), and chicken gall (Ji Dan, JD) were analyzed by UHPLC-QTOF-MSE, and the MS data, combined with multivariate analysis methods, were used to distinguish between them. Meanwhile, the potential chemical composition markers that contribute to their differences were further explored. RESULTS: The results showed that XD and six other animals' bile can be distinguished from each other obviously, with 27 ions with VIP > 1.0. We preliminarily identified 10 different bile acid-like components in XD and the other animals' bile with significant differences (p < 0.01) and VIP > 1.0, such as tauroursodeoxycholic acid, Glycohyodeoxycholic acid, and Glycodeoxycholic acid. CONCLUSIONS: The developed method was efficient and rapid in accurately distinguishing between XD and six other animals' bile. Based on the obtained chemical composition markers, it is beneficial to strengthen quality control for bile medicines.

[Authenticity discrimination for Galli Gigerii Endothelium Corneum based on UPLC-MS/MS and peptidomics].

Peptidomics was employed to systematically analyze the characteristic peptides in Galli Gigerii Endothelium Corneum and its adulterants and establish a method for distinguishing Galli Gigerii Endothelium Corneum from its adulterants, including the gizzard membranes from ducks, geese, and pigeons. UPLC-Q-Exactive Orbitrap-MS was combined with multivariate statistical analysis to analyze the peptides in Galli Gigerii Endothelium Corneum and its adulterants. The structures of peptides were identified by pNovo combined with manual recognition of spectra, and synthetic peptide standards were used for validation. LC-MS/MS was used to optimize the sample pre-processing conditions, including the extraction procedure, extraction time, extraction solvents, and solvent volumes, for the characteristic peptide LESY in Galli Gigerii Endothelium Corneum. Multiple reaction monitoring(MRM) in the ESI~+ mode with m/z 511.24→269.11 and 511.24→243.13 as detection ions was employed for qualitative and quantitative analyses. The established UPLC-MS/MS method demonstrated good specificity, stability, and durability. The content of LESY in 16 batches of Galli Gigerii Endothelium Corneum samples ranged from 55.03 to 113.36 µg·g~(-1). Additionally, a qualitative detection method for the common peptide RDPVLVSR in adulterants was established with m/z 471.28→785.45 and 471.28→670.41 as the detection ions. This study established a convenient, rapid, and accurate detection method for the characteristic peptides in Galli Gigerii Endothelium Corneum and its adulterants. The method possesses good specificity, stability, and durability, providing a valuable reference for the identification and quality control of Galli Gigerii Endothelium Corneum and other traditional Chinese medicines derived from animal sources.

A green, fluorescent probe employing erythrosine-B for tracing the accidental administration of levamisole in milk and plasma samples.

A simple and sensitive fluorescent probe has been developed and optimized to detect the non-intentional administration of levamisole (LVM). LVM is used as an anthelmintic therapy in cows, and hence, its residues appear in the drained milk until 60 hours after administering the drug. Meanwhile, levamisole is known to be an adulterant to cocaine and could be detected in addicts' plasma samples. Owing to its severe side effects, including agranulocytosis, which is lethal in many cases, detection and quantification of LVM in milk and plasma samples are of utmost importance. Therefore, a sensitive and selective analytical method is required for this purpose. This work develops a highly fluorescent probe obtained through the reaction between LVM and erythrosine-B in an acidic medium, where the produced ion pair complex has been measured at 553 nm after excitation at 528 nm. The proposed method provides linearity over the concentration range of 0.5-2.0 µg mL-1 for LVM, with a corresponding detection and quantitation limit of 0.5 and 0.3 µg mL-1. Full validation was performed, permitting the application of the suggested method to perform simple extraction steps. All the applied procedures followed the guidelines offered by green analytical chemistry, where the Green Analytical Procedure Index (GAPI) assessed the greenness of the proposed tool, and the yielded pictograms proved the eco-friendliness of the offered tool.

Activity-based detection of synthetic cannabinoid receptor agonists in plant materials.

BACKGROUND: Since late 2019, fortification of 'regular' cannabis plant material with synthetic cannabinoid receptor agonists (SCRAs) has become a notable phenomenon on the drug market. As many SCRAs pose a higher health risk than genuine cannabis, recognizing SCRA-adulterated cannabis is important from a harm reduction perspective. However, this is not always an easy task as adulterated cannabis may only be distinguished from genuine cannabis by dedicated, often expensive and time-consuming analytical techniques. In addition, the dynamic nature of the SCRA market renders identification of fortified samples a challenging task. Therefore, we established and applied an in vitro cannabinoid receptor 1 (CB1) activity-based procedure to screen plant material for the presence of SCRAs. METHODS: The assay principle relies on the functional complementation of a split-nanoluciferase following recruitment of ß-arrestin 2 to activated CB1. A straightforward sample preparation, encompassing methanolic extraction and dilution, was optimized for plant matrices, including cannabis, spiked with 5 µg/mg of the SCRA CP55,940. RESULTS: The bioassay successfully detected all samples of a set (n = 24) of analytically confirmed authentic Spice products, additionally providing relevant information on the 'strength' of a preparation and whether different samples may have originated from separate batches or possibly the same production batch. Finally, the methodology was applied to assess the occurrence of SCRA adulteration in a large set (n = 252) of herbal materials collected at an international dance festival. This did not reveal any positives, i.e. there were no samples that yielded a relevant CB1 activation. CONCLUSION: In summary, we established SCRA screening of herbal materials as a new application for the activity-based CB1 bioassay. The simplicity of the sample preparation, the rapid results and the universal character of the bioassay render it an effective and future-proof tool for evaluating herbal materials for the presence of SCRAs, which is relevant in the context of harm reduction.

Outbreak of Ralstonia pickettii associated with contamination of saline products distributed internationally, the United Kingdom, 2024.

We describe an outbreak of Ralstonia pickettii in the United Kingdom, with isolates genetically indistinguishable from a 2023 Australian outbreak linked to internationally distributed saline solutions. Confirmed cases (n = 3) had bacteraemia, clinically relevant infection, indwelling venous lines and frequent healthcare contact. Multi-stakeholder intervention was required including product recall and risk communications. We recommend a low threshold for investigating clusters of Ralstonia species and similar opportunistic pathogens, considering contaminated product sources. Effective mitigation requires multi-agency partnership and international collaboration.

Molecular quantification of herbs (Herb-Q): a pyrosequencing-based approach and its application in Pinellia ternata.

Variations in herb dosage due to species adulteration and dosing inaccuracies can substantially affect clinical safety and efficacy. Accurate species quantification remains challenging, as current methods often yield inconsistent results. This study introduces a novel pyrosequencing-based technique, termed herb molecular quantification (Herb-Q), designed to precisely quantify herbal products. We evaluated its effectiveness using Pinellia ternata and five of its adulterants. Initially, we assessed commonly used DNA barcodes with sequences from a public database, identifying two candidate regions, Maturase K (matK) and internal transcribed spacer 2 (ITS2), for screening specific single nucleotide polymorphism (SNP) loci, allowing for species-specific identification. These loci were validated by amplifying and sequencing genomic material from collected samples. Our validation studies showed that Herb-Q demonstrated excellent linearity, accuracy, repeatability, and detection limits. We established quantitative standard curves with high R2 values (> 0.99) to enable precise species quantification, which were combined with external standards to provide clear and accurate visual quantification results. The average bias in quantifying the tuber of P. ternata was 2.38%, confirming that Herb-Q can accurately identify and quantify herbal product constituents. Moreover, the entire quantification process took less than 4 h. This study presents a novel, rapid method for accurately quantifying species in herbal products and advances the application of DNA barcoding from species identification to quantitative detection.

Reconstruction of the historic time course of blood-borne virus contamination of clotting factor concentrates, 1974-1992.

Factor VIII and IX clotting factor concentrates manufactured from pooled plasma have been identified as potent sources of virus infection in persons with hemophilia (PWHs) in the 1970s and 1980s. To investigate the range and diversity of viruses over this period, we analysed 24 clotting factor concentrates for several blood-borne viruses. Nucleic acid was extracted from 14 commercially produced clotting factors and 10 from nonremunerated donors, preserved in lyophilized form (expiry dates: 1974-1992). Clotting factors were tested by commercial and in-house quantitative PCRs for blood-borne viruses hepatitis A, B, C and E viruses (HAV, HBV, HCV, HEV), HIV- types 1/2, parvoviruses B19V and PARV4, and human pegiviruses types 1 and 2 (HPgV-1,-2). HCV and HPgV-1 were the most frequently detected viruses (both 14/24 tested) primarily in commercial clotting factors, with frequently extremely high viral loads in the late 1970s-1985 and a diverse range of HCV genotypes. Detection frequencies sharply declined following introduction of virus inactivation. HIV-1, HBV, and HAV were less frequently detected (3/24, 1/24, and 1/24 respectively); none were positive for HEV. Contrastingly, B19V and PARV4 were detected throughout the study period, even after introduction of dry heat treatment, consistent with ongoing documented transmission to PWHs into the early 1990s. While hemophilia treatment is now largely based on recombinant factor VIII/IX in the UK and elsewhere, the comprehensive screen of historical plasma-derived clotting factors reveals extensive exposure of PWHs to blood-borne viruses throughout 1970s-early 1990s, and the epidemiological and manufacturing parameters that influenced clotting factor contamination.

Exploration and detection of nitrosamine impurity nitroso-STG-19 in sitagliptin tablets and API as well as nitrites in excipients by LC-MS/MS methods.

The Food and Drug Administration (FDA) recently reported a new nitrosamine impurity in sitagliptin that was named nitroso-STG-19 (NTTP), whose acceptable intake limit was extremely low at 37 ng per day. In addition, NTTP was found to be a degradation impurity in sitagliptin tablets, which was formed by the reaction of 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine hydrochloride and nitrite salts introduced via excipients. Consequently, the NTTP content in tablets was larger than that in active pharmaceutical ingredients (APIs). To control the impurity, an ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) procedure for the detection of NTTP in sitagliptin phosphate tablets and APIs was developed and validated. Furthermore, a derivatization method for the detection of nitrite salts at lower concentration was developed to select applicable excipients to decelerate the generation of NTTP. During validation of the analytical procedure for NTTP, the quantitation limit (LOQ) of NTTP was 56 ppb (0.056 ng mL-1), the linear correlation coefficient was 0.9998, and recoveries of NTTP in spiked samples ranged from 95.5% to 105.2%, indicating that the method is rapid, sensitive and accurate for an NTTP test. In the nitrite salt detection method, the LOQ was 0.21 ng mL-1, and recoveries of NTTP in spiked samples ranged from 87.6% to 107.8%, indicating a sensitive and accurate method, suitable for screening appropriate pharmaceutical excipients.

A (RP)UHPLC/UV analytical method to quantify dsRNA during the mRNA vaccine manufacturing process.

dsRNA is a product related impurity produced during the mRNA manufacturing process. The established immuno-based detection methods lack the flexibility and speed required to be applied throughout the manufacturing process. The RP-HPLC method developed outperforms these in terms of precision, broader detection range, LOD and LOQ, as well as in output variance. Using this method, dsRNA can be quantified in under 30 min for a single sample.

Potential of Powder Rheology for Detecting Unforeseen Cross-Contamination of Foreign Active Pharmaceutical Ingredients.

Unexpected cross-contamination by foreign components during the manufacturing and quality control of pharmaceutical products poses a serious threat to the stable supply of drugs and the safety of customers. In Japan, in 2020, a mix-up containing a sleeping drug went undetected by liquid chromatography during the final quality test because the test focused only on the main active pharmaceutical ingredient (API) and known impurities. In this study, we assessed the ability of a powder rheometer to analyze powder characteristics in detail to determine whether it can detect the influence of foreign APIs on powder flow. Aspirin, which was used as the host API, was combined with the guest APIs (acetaminophen from two manufacturers and albumin tannate) and subsequently subjected to shear and stability tests. The influence of known lubricants (magnesium stearate and leucine) on powder flow was also evaluated for standardized comparison. Using microscopic morphological analysis, the surface of the powder was observed to confirm physical interactions between the host and guest APIs. In most cases, the guest APIs were statistically detected due to characteristics such as their powder diameter, pre-milling, and cohesion properties. Furthermore, we evaluated the flowability of a formulation incorporating guest APIs for direct compression method along with additives such as microcrystalline cellulose, potato starch, and lactose. Even in the presence of several additives, the influence of the added guest APIs was successfully detected. In conclusion, powder rheometry is a promising method for ensuring stable product quality and reducing the risk of unforeseen cross-contamination by foreign APIs.

Study on the impurity profiles of cloxacillin and flucloxacillin based on liquid chromatography tandem ion trap/time-of-flight mass spectrometry.

RATIONALE: Cloxacillin and flucloxacillin are prone to degradation and polymerization in humid and hot environments, and their polymers have long been recognized to trigger allergic manifestations. A series of the degradation and polymerized impurities in cloxacillin and flucloxacillin were separated and characterized to ensure safe use of these drugs by the public. METHODS: By studying the chromatographic behavior of the degradation impurities and polymerized impurities in reversed-phase high-performance liquid chromatography (RP-HPLC) gradient elution, the impurities in cloxacillin and flucloxacillin were effectively separated and eluted. RP-HPLC tandem ion trap/time-of-flight mass spectrometry (MS) was applied to characterize the structures of unknown impurities eluted from the RP-HPLC methods for cloxacillin and flucloxacillin. The mechanisms of formation of the impurities in cloxacillin and flucloxacillin were also investigated. RESULTS: The structures of 10 unknown impurities in cloxacillin and 8 unknown impurities in flucloxacillin were elucidated based on the high-resolution MSn data at positive and negative modes, respectively. Six polymerized impurities were found and characterized, of which three were from the polymerization of cloxacillin and three were from the polymerization of flucloxacillin. CONCLUSIONS: The study on the impurity profiles of cloxacillin and flucloxacillin provided a scientific basis for improving their production processes and quality control.

Multiple use of preservative-free single dose unit dexamethasone 0.1% eye drops is safe within 24 hours.

BACKGROUND: Unpreserved single-dose unit (SDU) eye drops are commonly used to avoid benzalkonium chloride-related toxicity. Although intended for single use, many patients report off-label repeated use of SDUs over a prolonged period. We investigated whether repeated use of dexamethasone 0.1% SDUs in the same patient increases the bacterial contamination rate. METHODS: We prospectively enrolled patients scheduled for inpatient corneal and glaucoma surgery receiving dexamethasone 0.1% SDU four times per day from the same vial. To assess contamination rates, one drop from the vial was cultured immediately after opening the SDU (t0), 10 hours later after four drop applications (t10) and 24 hours after opening without further drop applications (t24). Conjunctival swabs were taken before and after drop application. Contamination rate was assessed with a standard clinical culturing protocol without introducing a positive control. RESULTS: 110 eyes of 109 patients were evaluated. Drops collected immediately after opening the SDU (t0) were contaminated in 9/110 cultures (8.1%). At t10, 13/110 cultures were contaminated (11.8%; p=0.267) and 11/110 at t24 (10.0%; t24 vs t0; p=1.00). In 5 of 21 cases of contaminated drops at t10 and/or t24, the same isolates were cultured from the initial conjunctival swab and the SDU. In three cases, the same bacterial species was found in consecutive samples. CONCLUSION: The contamination rate of the SDU did not increase after multiple use within 24 hours. Contamination from fingertip flora was more likely than from ocular surface flora. Reuse of dexamethasone 0.1% SDU in the same patient within 24 hours appears to be safe.

Rapid identification and quantification of Pseudostellaria heterophylla with its adulterants by HPLC-CAD fingerprint combined with improved quantitative analysis of multi-components by single marker (QAMS).

The P. heterophylla and its adulterants were identified by HPLC-CAD fingerprint of sucrose and oligosaccharides in P. heterophylla. The improved quantitative analysis of multi-components with a single marker (iQAMS) was further established for simultaneous determinations of sucrose and oligosaccharides in P. heterophylla. The HPLC-CAD fingerprint and similarity coefficients between P. heterophylla and its adulterants showed significant differences. The relative errors (REs) between iQAMS method and external standard method (ESM) were below 3.00%, but significant difference was shown between iQAMS (different marker for whole program with gradient elution) and QAMS (one marker for whole program with gradient elution), indicating that QAMS method should be improved, especially for gradient elution which influence the response of analytes. The accuracy, precision, reproducibility, and stability of this method were validated which exhibited satisfactory results, indicating that iQAMS method could be used for quantitative analysis of sucrose and oligosaccharides in P. heterophylla instead of ESM. The iQAMS combined with HPLC-CAD fingerprint could be used to determine the content of each oligosaccharide, and it can be used for quality control of P. heterophylla.

A drug-excipient interaction impurity of bromhexine hydrochloride injection: Structure and formation mechanism elucidation.

A long-term stability study using high performance liquid chromatography (HPLC) revealed an unidentified impurity in the bromhexine hydrochloride injection, which was employed as a mucolytic agent. Investigations into stress degradation and elemental impurities revealed one of the elemental impurities Fe3+ in this injection as the primary generator of these impurities. This impurity, named N-carboxymethyl bromhexine, was a product formed during drug-excipient interaction between bromhexine and tartaric acid with Fe3+. The structure of the impurity was identified through ultra-high-performance liquid chromatography with diode array detector (UHPLC-DAD), liquid chromatograph mass spectrometer (LC-MS). Further, the formation mechanism of the impurity was discussed. Overall, this study elucidates the cause, origin, and mechanism of an unknown impurity in bromhexine hydrochloride injection, providing a basis for quality control for bromhexine hydrochloride injections and drug products containing both amine and tartaric acid.

Metformin drugs under simulated gastric conditions can generate high nitrite-dependent levels of N-nitrosodimethylamine.

N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), group 2A carcinogens, were detected in finished drug products, including metformin, ranitidine, sartans and other drugs which caused multiple recalls in the USA and Europe. Important studies also reported the formation of NDMA when ranitidine and nitrite were added to simulated gastric fluid. Our objective was to screen finished drug products from Europe and USA for nitrosamine impurities and investigate the formation of NDMA in metformin finished drug products when added to simulated gastric fluid. One dosage unit of 30 different commercially available drugs, including metformin, sartans, and ranitidine were tested for NDMA, NDEA, and dimethylformamide (DMF) impurities, using a liquid chromatography-mass spectrometry (LC-MS) method. Then, 6 metformin finished drug products were tested in stomach conditions for 2 h at 37 °C in a 100 mL solution with a pH of 2.5 and different nitrite concentrations (40, 10, 1, 0.1 mM) and tested for NDMA, and DMF using LC-MS. We measured NDMA, NDEA, and DMF in 30 finished drug products. NDMA and DMF were quantified for metformin drug products in simulated gastric fluid with different nitrite concentrations. None of the 30 drugs showed concerning levels of NDMA, NDEA, or DMF when tested as single tablets. However, when metformin tablets are added to simulated gastric fluid solutions with high nitrite concentrations (40 mM and 10 mM), NDMA can reach amounts of thousands of nanograms per tablet. At the closest concentration to physiologic conditions we used, 1 mM, NDMA is still present in the hundreds of nanograms in some metformin products. In this in vitro study, nitrite concentration had a very important effect on NDMA quantification in metformin tablets added to simulated gastric fluid. 1 mM nitrite caused an increase above the acceptable daily intake set by the U.S. Food and Drug Administration (FDA) for some of the metformin drugs. 10 mM, 40 mM nitrite solutions generated NDMA amounts exceeding by more than a hundred times the acceptable daily intake set by the FDA of 96 nanograms. These findings suggest that metformin can react with nitrite in gastric-like conditions and generate NDMA. Thus, patients taking metformin could be exposed to NDMA when high nitrite levels are present in their stomach, and we recommend including a statement within the Patient Package Inserts/Instructions for use.

Determination of nitrobenzene potential genotoxic impurities in nifedipine with GC-MS.

There is an increasing scientific interest in the detection of genotoxic impurities (GTIs), with nitrobenzene compounds being considered potential genotoxic impurities due to their structural alerts, which demonstrates a threat to drug safety for patient. While current reports on the detection of nifedipine impurity primarily focus on general impurities in nifedipine. In this study, an effective and simple gas chromatography-mass spectrometry (GC-MS) method was established and verified for the separation and quantification of 2-nitrotoluene, 2-nitrobenzyl alcohol, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, 4-nitrobenzaldehyde, and 2-nitrobenzyl bromide in nifedipine, which have not been previously reported. The validation of this GC-MS method was conducted following the International Conference of Harmonization (ICH) guidelines, exhibiting good linearity within the range of 2-40 µg/g and accuracy between 84.6 % and 107.8 %, the RSD% of intra-day and inter-day precision was in the range of 1.77-4.55 %, stability and robustness also met acceptance criteria. This method filled the gap in detection method for nitrobenzene compounds in nifedipine, offering a novel method and technical support for nifedipine quality control.

Identification and structural elucidation of an oxidation product generated during stability studies of Cabergoline drug product.

Cabergoline is a dopamine agonist with applications as anti-Parkinson drug and prolactin inhibitor. The cabergoline drug product Laktostop® 50 µg/mL is used in veterinary medicine for lactation suppression in cats and dogs e.g. during false pregnancy. Recently, during ongoing HPLC stability testing of Laktostop® 50 µg/mL a new oxidation product of Cabergoline was identified. A synthesis starting from Cabergoline was developed, followed by full characterization of the unknown impurity. Preliminary HPLC and LC-MS analyses indicated the unknown impurity as mono-oxygenated product of Cabergoline (Cabergoline N-oxide) that is presumably formed with oxygen by a radical mechanism. Thus, Cabergoline was treated with oxidizing agents such as m-chloroperoxybenzoic acid to afford the desired Cabergoline-N-oxide as a byproduct. After isolation by column chromatography, NMR and LC-MS-MS studies provided evidence that oxidation occurred at the N-allyl nitrogen of Cabergoline to form Cabergoline-N-oxide. © 1905 Elsevier Science. All rights reserved.

A multi-analyte assay of opioids in API and drug products using HPLC and HRMS.

Surveillance testing is an essential component to ensuring safe, effective, and high-quality drug products are available in the commercially marketed US supply chain. Surveillance allows the agency to assess product quality and monitor for potential adulteration of drug products being used by consumers. Opioid drug products can be adulterated to enhance the effect of the intended active ingredient. Numerous accounts have been reported where fentanyl has been used as an adulterant in illicit street drugs such as heroin, cocaine, or methamphetamine. To efficiently surveil the legitimate opioid supply chain, an analytical method with the ability to simultaneously detect, identify and quantify opioid molecules is desired. In this study, a multi-opioid protocol (MOP) using liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) technology was developed and validated for the detection and quantification of 27 opioid drugs. The MOP analytical procedure was applied to the analysis of drug substance and finished dosage forms. MOP was used to identify and quantify active pharmaceutical ingredients (API) listed on the label claim, and in the case of suspected economically motivated adulteration could identify and quantify undeclared opioid APIs. The analytical method analysis time was 16 minutes and the LOD and LOQ in full MS mode were (average) 0.3 and 0.8 ng/mL, respectively. The validation criteria parameters were satisfactory based on international guidelines (ICH). The MOP was successfully applied to the analysis of over 160 drug substances and finished products. For all samples tested in the study, their identities were confirmed, and assays met specifications. Overall, there was no evidence of illegal substitution or adulteration in any of the ingredients and products tested from the legitimate commercial marketed US supply chain.

Investigation into the genotoxic impurity, 1-methyl-4-nitrosopiperazine, in rifampicin.

This study assessed the presence of the genotoxic impurity 1-methyl-4-nitrosopiperazine (MNP) in 27 batches of rifampicin capsules obtained from 11 manufacturers in China. While they were below the temporary limit of 5 ppm set by the US Food and Drug Administration, the observed levels (0.33-2.36 ppm) exceeded the acceptable threshold of 0.16 ppm. Building upon preliminary findings and degradation experiments, we concluded that MNP is a by-product of the oxidative degradation of rifampicin or is introduced via oxidation or nitrosation during the synthesis process involving 1-methyl-4-aminopiperazine. The pathways of MNP formation were confirmed in this study. Furthermore, we observed that the addition of antioxidants, sealed storage, and selection of dominant crystal forms can aid in controlling MNP levels.