Cardiovascular Safety Pharmacology of Sibutramine

Points to consider for revising the ICH S7A guideline on safety and secondary pharmacology

Although the ICH S7A guideline on safety pharmacology largely achieved its objective, a proportion of remaining adverse drug reactions and attrition can be attributed in part to gaps in safety and secondary pharmacology assessments. Advances in science, technology, drug development paradigm and regulatory practices necessitate revisiting and evolving ICH S7A to address these limitations. The anticipated completion of the ICH S7B Q&As by end of 2025 provides an opportunity to integrate its outcomes with ICH S7A into a comprehensive, modality-agnostic sustainable over time framework. Such consolidation could streamline guidance, enhance usability, and align regulatory expectations globally. This proposed revision should aim to address key aspects of safety and secondary pharmacology, including the definition of adversity, the integration of human-relevant in vitro and in silico models, and the adoption of state-of-the-art in vivo platforms. Further considerations should include the development of principles for model and assay validation, the promotion of integrated risk assessment frameworks, and incorporation of weight of evidence approaches. Revised guideline would also emphasize sustainable practices by adapting to evolving therapeutic modalities, while reducing reliance on animal testing through New Approach Methodologies. The revision seeks to enhance the benefit-risk evaluation of drug candidates, refine clinical monitoring, foster regulatory acceptance, and streamline drug development. This comprehensive update has the potential to not only optimize drug safety evaluations but also to align industry practices with modern scientific advancements and ethical considerations, ensuring a more robust and efficient pathway for therapeutic innovation.

Quantitation of sibutramine in human hair using gas chromatography-isotope dilution tandem mass spectrometry

PURPOSE

An analytical method for quantitation of sibutramine in human hair using gas chromatography (GC)-isotope dilution tandem mass spectrometry (MS/MS) was newly established. In this article, a case is presented, in which a 3.5-year-old male child accidentally ingested chocolate-like product containing sibutramine, showing various symptoms; he could survived the crisis. About 1 month after the incident, his scalp hair sample was subjected to analysis for the causative sibutramine.

METHOD

After cryo-grinding for the hair sample, target compound was extracted with methanol, and the solvent layer was evaporated to dryness. The residue was reconstituted in methanol and analyzed by GC-MS/MS, using the selected reaction monitoring (SRM) mode with a deuterated isotope internal standard.

RESULTS

The substance was identified as sibutramine; its concentration in the hair sample of the child was 58.6 pg/mg. The calibration curve of sibutramine in hair samples had a good linear relationship in the concentration range of 20-200 pg/mg (r > 0.99); the extraction recovery rate 85.2-91.8%; the interday and intraday precision and accuracy (bias) examined not greater than 9.6%. Sibutramine in human hair had good stability under 3 different storage conditions at room (20 °C), refrigerated (4 °C) and frozen ( - 20 °C) temperatures for at least 7 days.

CONCLUSIONS

It should be expected that the method established in this study would contribute to rapid determinations of sibutramine. To our knowledge, this is the first report describing quantitation of sibutramine in an authentic human hair sample by GC-MS/MS.

Novel Noninvasive Approaches to the Treatment of Obesity: From Pharmacotherapy to Gene Therapy

Recent insights into the pathophysiologic underlying mechanisms of obesity have led to the discovery of several promising drug targets and novel therapeutic strategies to address the global obesity epidemic and its comorbidities. Current pharmacologic options for obesity management are largely limited in number and of modest efficacy/safety profile. Therefore, the need for safe and more efficacious new agents is urgent. Drugs that are currently under investigation modulate targets across a broad range of systems and tissues, including the central nervous system, gastrointestinal hormones, adipose tissue, kidney, liver, and skeletal muscle. Beyond pharmacotherapeutics, other potential antiobesity strategies are being explored, including novel drug delivery systems, vaccines, modulation of the gut microbiome, and gene therapy. The present review summarizes the pathophysiology of energy homeostasis and highlights pathways being explored in the effort to develop novel antiobesity medications and interventions but does not cover devices and bariatric methods. Emerging pharmacologic agents and alternative approaches targeting these pathways and relevant research in both animals and humans are presented in detail. Special emphasis is given to treatment options at the end of the development pipeline and closer to the clinic (ie, compounds that have a higher chance to be added to our therapeutic armamentarium in the near future). Ultimately, advancements in our understanding of the pathophysiology and interindividual variation of obesity may lead to multimodal and personalized approaches to obesity treatment that will result in safe, effective, and sustainable weight loss until the root causes of the problem are identified and addressed.

Interrelated In Vitro Mechanisms of Sibutramine-Induced Cardiotoxicity

Consumption of illicit pharmaceutical products containing sibutramine has been reported to cause cardiovascular toxicity problems. This study aimed to demonstrate the toxicity profile of sibutramine, and thereby provide important implications for the development of more effective strategies in both clinical approaches and drug design studies. Action potentials (APs) were determined from freshly isolated ventricular cardiomyocytes with whole-cell configuration of current clamp as online. The maximum amplitude of APs (MAPs), the resting membrane potential (RMP), and AP duration from the repolarization phases were calculated from original records. The voltage-dependent K+-channel currents (IK) were recorded in the presence of external Cd2+ and both inward and outward parts of the current were calculated, while their expression levels were determined with qPCR. The levels of intracellular free Ca2+ and H+ (pHi) as well as reactive oxygen species (ROS) were measured using either a ratiometric micro-spectrofluorometer or confocal microscope. The mechanical activity of isolated hearts was observed with Langendorff-perfusion system. Acute sibutramine applications (10-8-10-5 M) induced significant alterations in both MAPs and RMP as well as the repolarization phases of APs and IK in a concentration-dependent manner. Sibutramine (10 μM) induced Ca2+-release from the sarcoplasmic reticulum under either electrical or caffeine stimulation, whereas it depressed left ventricular developed pressure with a marked decrease in the end-diastolic pressure. pHi inhibition by sibutramine supports the observed negative alterations in contractility. Changes in mRNA levels of different IK subunits are consistent with the acute inhibition of the repolarizing IK, affecting AP parameters, and provoke the cardiotoxicity.

Toward a broader view of mechanisms of drug cardiotoxicity

Cardiotoxicity, defined as toxicity that affects the heart, is one of the most common adverse drug effects. Numerous drugs have been shown to have the potential to induce lethal arrhythmias by affecting cardiac electrophysiology, which is the focus of current preclinical testing. However, a substantial number of drugs can also affect cardiac function beyond electrophysiology. Within this broader sense of cardiotoxicity, this review discusses the key drug-protein interactions known to be involved in cardiotoxic drug response. We cover adverse effects of anticancer, central nervous system, genitourinary system, gastrointestinal, antihistaminic, anti-inflammatory, and anti-infective agents, illustrating that many share mechanisms of cardiotoxicity, including contractility, mitochondrial function, and cellular signaling.

From linked open data to molecular interaction: studying selectivity trends for ligands of the human serotonin and dopamine transporter

Retrieval of congeneric and consistent SAR data sets for protein targets of interest is still a laborious task to do if no appropriate in-house data set is available. However, combining integrated open data sources (such as the Open PHACTS Discovery Platform) with workflow tools now offers the possibility of querying across multiple domains and tailoring the search to the given research question. Starting from two phylogenetically related protein targets of interest (the human serotonin and dopamine transporters), the whole chemical compound space was explored by implementing a scaffold-based clustering of compounds possessing biological measurements for both targets. In addition, potential hERG blocking liabilities were included. The workflow allowed studying the selectivity trends of scaffold series, identifying potentially harmful compound series, and performing SAR, docking studies and molecular dynamics (MD) simulations for a consistent data set of 56 cathinones. This delivered useful insights into driving determinants for hDAT selectivity over hSERT. With respect to the scaffold-based analyses it should be noted that the cathinone data set could be retrieved only when Murcko scaffold analyses were combined with similarity searches such as a common substructure search.

Pharmacokinetics of YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, in rats

YJC-10592, a novel chemokine receptor 2 (CCR-2) antagonist, was developed for treating asthma and atopic dermatitis. We studied the pharmacokinetic characteristics of YJC-10592 after intravenous (5, 10 and 20 mg/kg) and oral (100 and 200 mg/kg) administration of the drug to rats. Tissue distribution of YJC-10592 was also evaluated after intravenous administration of YJC-10592, 10 mg/kg, to rats. The pharmacokinetics of YJC-10592 was dose-dependent from 20 mg/kg after intravenous administration to rats. The values of the area under the plasma concentration-time curve from time zero to infinity (AUC) of YJC-10592 were dose-dependent from 20 mg/kg and the time-averaged total body (CL) and nonrenal (CLNR) clearances of YJC-10592 were significantly lower at dose of 20 mg/kg, suggesting that saturable metabolism may be involved. The absolute bioavailability (F) of YJC-10592 was generally low (<2.55 %) for both oral doses due to incomplete absorption and low urinary excretion. YJC-10592 had a great affinity to all rat tissues studied except brain, which was supported by a relatively high value of the apparent volume of distribution at steady state (V ss) (890-1385 mL/kg). In conclusion, YJC-10592 showed dose-dependent pharmacokinetics and low F value due to slower elimination and incomplete absorption.