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Introduction: The proliferation of new psychoactive substances (NPS) poses a significant challenge to clinical and forensic toxicology laboratories. N,N-dimethylpentylone, a novel synthetic cathinone, has emerged as a public health concern. The aims of this study are to describe the clinical presentation of N,N-dimethylpentylone poisoning, to describe detection methods, and to deduce its metabolic pathways., Methods: Clinical data was collected and reviewed retrospectively from patients with confirmed N,N-dimethylpentylone exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify N,N-dimethylpentylone and its metabolites in urine samples. The metabolic pathway was characterised by comparison of the detected substances with reference standards., Results: Eight cases were included in the case series. Seven different metabolites of N,N-dimethylpentylone were identified in in vivo patient urine samples, where the two major metabolic pathways were proposed to be opening of the 5-membered ring and reduction of carboxide. All patients presented with neuropsychiatric and/or cardiovascular symptoms. Co-ingestion with other substances was reported in all cases. One patient requiring intensive care was described in detail. All patients eventually recovered. The analytical method allowed the simultaneous identification of N,N-dimethylpentylone, pentylone and bisdesmethyl-N,N-dimethylpentylone, as well as other drugs of abuse in patient samples., Conclusion: N,N-dimethylpentylone appears to be less potent than its metabolite pentylone. Co-ingestion with other drugs of abuse is common. Poisoning cases have neuropsychiatric and cardiovascular manifestations. An updated and comprehensive laboratory method is needed for its detection., Competing Interests: Declaration of Competing Interest All authors have disclosed no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Competing Interests: All authors have disclosed no conflicts of interest.

Background & Aims: Peripartum prophylaxis (PP) with tenofovir disoproxil fumarate (TDF) is the standard of care to prevent mother-to-child transmission of chronic hepatitis B (CHB) infection in mothers who are highly viremic. We investigated the maternal and infant outcomes in a large Chinese cohort of TDF-treated CHB pregnant participants., Methods: In this prospective study, treatment-naive mothers with CHB and highly viremic (HBV DNA ≥200,000 IU/ml) but without cirrhosis were treated with TDF at 24-28 weeks of pregnancy. In accordance with Chinese CHB guidelines, TDF was stopped at delivery or ≥4 weeks postpartum. Serum HBV DNA and alanine aminotransferase were monitored every 6-8 weeks to determine virological relapse (VR). Infants received standard neonatal immunization, and HBV serology was checked at 7-12 months of age., Results: Among 330 participants recruited (median age 30, 82.7% HBeAg+, median HBV DNA 7.82 log IU/ml), TDF was stopped at delivery in 66.4% and at ≥4 weeks in 33.6%. VR was observed in 98.3%, among which 11.6% were retreated with TDF. Timing of TDF cessation did not alter the risk of VR (99.0 vs . 96.9%), clinical relapse (19.5 vs . 14.3%), or retreatment (12.6 vs . 10.1%) (all p  > 0.05). A similar proportion of patients developed alanine aminotransferase flare five times (1.1 vs . 2.1%; p  = 0.464) and 10 times (0.5 vs . 0%; p  = 0.669) above the upper limit of normal (ULN) in the early withdrawal and late withdrawal groups, respectively. No infants developed HBsAg-positivity., Conclusions: PP-TDF and neonatal immunization were highly effective in preventing mother-to-child transmission of HBV in mothers who are highly viremic. Timing of cessation of PP-TDF did not affect the risk of VR or retreatment., Impact and Implications: In pregnant mothers with chronic hepatitis B infection who are started on peripartum tenofovir to prevent mother-to-child-transmission (MTCT), the optimal timing for antiviral withdrawal during the postpartum period remains unknown. This prospective study demonstrates that stopping tenofovir immediately at delivery, compared with longer treatment duration of tenofovir, did not lead to an increased risk of virological relapse, retreatment, or transmission of the virus to the baby. Shortening the duration of peripartum antiviral prophylaxis from 12 weeks to immediately after delivery can be considered. The immediate withdrawal of peripartum tenofovir, combined with standard neonatal immunization schemes, is 100% effective in preventing MTCT among pregnant mothers with CHB who are highly viremic, with a high rate of vaccine response in infants., Competing Interests: MFY received research funding from Assembly Biosciences, Arrowhead Pharmaceuticals, Bristol Myer Squibb, Fujirebio Incorporation, Gilead Sciences, Merck Sharp and Dohme, Springbank Pharmaceuticals, Sysmex Corporation, and Roche, and is an advisory board member of and/or received research funding from AbbVie, Aligos Therarpeutics, Arbutus Biopharma, Bristol Myer Squibb, Dicerna Pharmaceuticals, Finch Therapeutics, GlaxoSmithKline, Gilead Sciences, Janssen, Merck Sharp and Dohme, Clear B Therapeutics, Springbank Pharmaceuticals, and Roche. WKS received speaker’s fees from AstraZeneca; is an advisory board member of and received speaker’s fees from Abbott; received research funding from Alexion Pharmaceuticals, Boehringer Ingelheim, Pfizer, and Ribo Life Science; and is an advisory board member of and received speaker’s fees and researching funding from Gilead Sciences. The other authors have nothing to disclose. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2024 The Authors.)