RE-ENGINEERING PARACETAMOL (ACETAMINOPHEN) IN THE 21ST CENTURY: MOLECULAR PHARMACOLOGY, SYSTEMS TOXICOLOGY, AND NANO-THERAPEUTIC INNOVATIONS

Paracetamol (acetaminophen) continues to occupy a central position in global therapeutics as a first-line analgesic and antipyretic agent, yet its mechanistic intricacies and safety profile remain subjects of sustained scientific interrogation. Traditionally perceived as a peripherally weak cyclooxygenase (COX) inhibitor, contemporary evidence has repositioned paracetamol as a centrally acting drug with multifaceted pharmacodynamics involving serotonergic modulation, endocannabinoid signaling, transient receptor potential vanilloid 1 (TRPV1) activation, and redox-sensitive pathways. This review provides a comprehensive and technically rigorous synthesis of paracetamol’s advanced pharmacological landscape, integrating classical biochemical pathways with emerging insights from systems pharmacology and nanomedicine. A critical focus is placed on its hepatic metabolism, wherein a fraction undergoes cytochrome P450-mediated bioactivation to N-acetyl-p-benzoquinone imine (NAPQI), a highly reactive electrophile responsible for dose-dependent hepatotoxicity. The pathogenesis of paracetamol-induced liver injury is explored through mitochondrial dysfunction, oxidative stress amplification, sterile inflammation, and immune-mediated signaling cascades. Furthermore, recent advances in nano-enabled drug delivery systems—including polymeric nanoparticles, lipid-based carriers, and smart hydrogels—are evaluated for their potential to enhance therapeutic index, optimize pharmacokinetics, and mitigate toxicity. The review also critically examines epidemiological evidence regarding chronic exposure risks, regulatory frameworks, and clinical controversies across diverse populations. By bridging molecular pharmacology with translational and technological innovations, this article aims to redefine the therapeutic narrative of paracetamol, providing a future-oriented perspective consistent with Scopus-indexed publication standards.