Massive paracetamol overdose: an observational study of the effect of activated charcoal and increased acetylcysteine dose (ATOM-2)

Context: Paracetamol is commonly taken in overdose, with increasing concerns that those taking “massive” overdoses have higher rates of hepatotoxicity and may require higher doses of acetylcysteine. The objective was to describe the clinical characteristics and outcomes of “massive” (≥?40?g) paracetamol overdoses.

Methods: Patients were identified through the Australian Paracetamol Project, a prospective observational study through Poisons Information Centres in NSW and Queensland, over 3 and 1.5 years, respectively, and retrospectively from three clinical toxicology unit databases (over 2.5 to 20 years). Included were immediate-release paracetamol overdoses ≥?40?g ingested over ≤?8?h. Outcomes measured included paracetamol ratio[defined as the ratio of the first paracetamol concentration taken 4–16?h post-ingestion to the standard (150?mg/L at 4?h) nomogram line at that time] and hepatotoxicity (ALT >1000?U/L).

Results: Two hundred paracetamol overdoses were analysed, reported median dose ingested was 50?g (interquartile range (IQR): 45–60?g) and median paracetamol ratio 1.9 (IQR: 1.4–2.9, n?=?173). One hundred and ninety-three received acetylcysteine at median time of 6.3?h (IQR: 4–9.3?h) post-ingestion. Twenty-eight (14%) developed hepatotoxicity, including six treated within 8?h of ingestion. Activated charcoal was administered to 49(25%), at median of 2?h post-ingestion (IQR:1.5-5?h). Those receiving activated charcoal (within 4?h of ingestion), had significantly lower paracetamol ratio versus those who did not: 1.4 (n?=?33, IQR: 1.1–1.6) versus 2.2 (n?=?140, IQR: 1.5–3.0) (p?hepatotoxicity [unadjusted OR: 0.12 (95% CI: <0.001–0.91); adjusted for time to acetylcysteine OR: 0.20 (95%CI: 0.002–1.74)].

Seventy-nine had a paracetamol ratio ≥2, 43 received an increased dose of acetylcysteine in the first 21?h; most commonly a double dose in the last bag (100 to 200?mg/kg/16?h). Those receiving increased acetylcysteine had a significant decrease risk of hepatotoxicity [OR:0.27 (95% CI: 0.08–0.94)]. The OR remained similar after adjustment for time to acetylcysteine and paracetamol ratio.

Conclusion: Massive paracetamol overdose can result in hepatotoxicity despite early treatment. Paracetamol concentrations were markedly reduced in those receiving activated charcoal within 4?h. In those with high paracetamol concentrations, treatment with increased acetylcysteine dose within 21?h was associated with a significant reduction in hepatotoxicity.     

海藻-昆布药对对大鼠肝微粒体代谢酶的影响及肝毒性研究

目的 发现不同剂量海藻-昆布药对提取物对大鼠肝微粒体代谢酶的诱导或抑制作用, 预测服用海藻-昆布药对时可能出现的药物-药物相互作用及肝脏毒性。方法 雌雄各半SD大鼠18只, 被随机分为海藻-昆布药对低、高剂量组和对照组, 低、高剂量组大鼠分别ig给予海藻-昆布药对提取物10.8、86.4 g/(kg·d), 连续经口给药15 d后麻醉处死, 取肝组织制备肝微粒体及HE染色石蜡切片。通过肝微粒体体外孵育方法测定3种肝脏CYP450同工酶特异性底物非那西丁(CYP1A2)、氯唑沙宗(CYP2E1)及咪达唑仑(CYP3A4)的降解和代谢产物生成量来评价肝药酶的诱导或抑制作用, 并以光镜下的组织病理切片检查来考察其肝毒性。结果 低剂量组大鼠无显著诱导或抑制3种CYP450代谢酶亚型1A2、2E1和3A4现象, 肝组织出现了肝窦扩张、轻度水肿等适应性改变, 高剂量组能显著诱导CYP3A4亚型, 但也不能显著的诱导或抑制肝微粒体代谢酶CYP1A2、CYP2E1亚型, 肝组织出现了脂肪变、点状坏死等可逆性损伤。结论 海藻-昆布药对具有诱导肝微粒体代谢酶CYP3A4的作用和轻微的肝细胞毒性, 高剂量经口给药能引起有临床意义的CYP450酶的诱导现象和肝脏损伤并可能导致不期望的药物-药物相互作用。     

EMA暂停使用口服酮康唑的受益-风险评估

欧洲药品管理局(EMA)经受益–风险评估后认为,口服酮康唑治疗真菌感染的肝损害风险超过受益。因此,EMA决定暂停这类药品在欧盟的上市许可。建议我国酮康唑口服制剂生产企业做酮康唑口服制剂的受益–风险评估,决定下一步采取的安全性措施,至少应修订药品说明书。在我国销售药品的生产企业应注意不断收集国外药品上市后的再评价信息,并及时采取修订说明书、暂停销售或撤市等适当的风险控制措施,确保用药安全。     

高CYPs酶活性大鼠原代肝细胞模型的建立及其在药物肝毒性评价中的应用

目的 建立一种灵敏、快速的高细胞色素P450(CYPs)酶活性的大鼠原代肝细胞模型,用于评价经CYPs酶代谢后产生肝毒性的药物。方法 分别采用苯巴比妥和β-萘黄酮两种CYPs酶广谱诱导剂构建大鼠原代肝细胞模型;应用“cocktail”探针底物法考察两种诱导剂对CYPs酶的影响;以基于CYPs酶代谢导致肝毒性的药物他克林(TAC)、双氯芬酸钠(DIC)和对乙酰氨基酚(PAR)为模型药物,评价所构建的高CYPs酶活性大鼠原代肝细胞模型与普通大鼠原代肝细胞间灵敏性的差异;应用所构建的高CYPs酶活性大鼠原代肝细胞模型评价维拉帕米(VER)的肝毒性。结果 与普通大鼠原代肝细胞相比,3种模型药物在高CYPs酶活性大鼠原代肝细胞中,在较低剂量时可使细胞上清液中乳酸脱氢酶(LDH)、细胞中活性氧(ROS)水平升高,线粒体膜电位(MMP)水平下降,或相同剂量下得到更严重的损伤结果,CYPs酶抑制剂1-aminobenzotriazole(ABT)和metyrapone(MET)能抑制这3种损伤的发生;100 μmol/L维拉帕米在普通大鼠原代肝细胞中并未引起LDH、ROS和MMP的改变,但在高CYPs活性大鼠原代肝细胞模型中,会引起细胞损伤,ABT和MET能抑制这种损伤。结论 经诱导建立的两种高CYPs酶活性大鼠原代肝细胞模型能更灵敏的评价基于CYPs酶代谢致毒药物的肝毒性;两种诱导剂诱导得到的高CYPs酶活性大鼠原代肝细胞模型对经不同CYPs酶亚型代谢的药物评价结果有各自优势。应用高CYPs酶活性大鼠原代肝细胞模型证实维拉帕米的致毒机制是经CYPs酶代谢产生肝毒性。     

转录组学技术在中药肝毒性研究中的应用

转录组学是功能基因组学研究中最活跃的领域之一,是一门在整体水平研究细胞中所有基因转录及转录调控规律的科学,在基础医学、生物学、微生物学和药学等领域已有广泛的应用。在中药研究领域中,该技术能从基因水平通过比较药物作用前后基因表达谱的变化对中药药理和毒理等方面进行评价。对该技术在中药研究领域的进展进行综述,主要介绍了转录组学技术在中药肝损伤筛选生物标志物和中药所致肝损伤机制研究中的应用,为该技术在中药领域的研究和发展提供有价值的参考。     

Adverse effects of antiretroviral therapy on liver hepatocytes and endothelium in HIV patients: An ultrastructural perspective

Human immunodeficiency virus and antiretroviral therapy (ART) together can be far more detrimental to liver cells than either of the two unaided. However, ultrastructural aspects of the synergistic effects of HIV and ART have been understudied. In a patient cohort receiving ART, this study characterizes ultrastructurally sinusoidal degeneration, hepatocytic aberrations, mitochondrial dysfunction, accumulation of bulky lipid droplets (steatosis), and occlusion of sinusoidal lumina. Mitochondrial dysfunction causes the accumulation of acetyl-CoA which leads to insulin upregulation and resistance, lipid synthesis, and steatosis. Lipid droplets deposited in the sinusoids could be the source of the blood’s lipid profile alterations in HIV patients on ART.     

Acetaminophen toxicity induces mitochondrial complex I inhibition in human liver tissue

Acetaminophen (APAP) is used worldwide and is regarded as safe in therapeutic concentrations but can cause acute liver failure in higher doses. High doses of APAP have been shown to inhibit complex I and II mitochondrial respiratory capacity in mouse hepatocytes, but human studies are lacking. Here, we studied mitochondrial respiratory capacity in human hepatic tissue ex vivo with increasing doses of APAP. Hepatic biopsies were obtained from 12 obese patients who underwent a Roux‐en‐Y gastric bypass (RYGB) or a sleeve gastrectomy surgery. Mitochondrial respiration was measured by high‐resolution respirometry. Therapeutic concentrations (≤0.13 mmol/L) of APAP did not inhibit state 3 complex I‐linked respiration. APAP concentrations of ≥2.0 mmol/L in the medium significantly reduced hepatic mitochondrial respiration in a dose‐dependent manner. Complex II‐linked mitochondrial respiration was not inhibited by APAP. We conclude that the mitochondrial respiratory capacity is affected by a hepato‐toxic effect of APAP, which involved complex I, but not complex II.     

Plant and Fungal Hepatotoxicities of Cattle in Australia,with a Focus on Minimally Understood Toxins

Plant- and fungus-derived hepatotoxins are a major cause of disease and production losses in ruminants in Australia and around the world. Many are well studied and described in the literature; however, this is not the case for a number of hepatotoxicities with economic and animal welfare impacts, such as acute bovine liver disease (ABLD), brassica-associated liver disease (BALD) and Trema tomentosa, Argentipallium blandowskianum and Lythrum hyssopifolia toxicity. Additionally, significant overlap in the clinical presentation and pathology of these conditions can present a diagnostic challenge for veterinarians. This review summarizes the current and most recently published knowledge of common plant- and fungus-associated hepatotoxins affecting cattle in Australia, with a focus on the mechanisms of toxicity and distinguishing diagnostic features. Consolidation of the current understanding of hepatotoxic mechanisms in cattle provides insight into the potential mechanisms of lesser-known toxins, including cellular and subcellular targets and potential metabolic pathways. In the absence of specific etiological investigations, the study of epidemiological, clinical and pathological features of hepatotoxicity provides valuable insights into potential toxic mechanisms and is integral for the successful diagnosis and management of these conditions.