TABLE 2.

Integrated pathway of aminoglycoside ototoxicity.

Stage	Timeframe	Key processes	Molecular markers	Intervention window
Entry	∼0–6 h	MET channel permeation; endocytosis; TRP channel entry	Fluorescent AG accumulation; endocytic vesicle formation	MET channel blockers (preclinical); endocytosis inhibitors (preclinical)
Mitochondrial targeting	∼2–12 h	Binding to 12S rRNA; protein synthesis inhibition; initial ROS production	Mitochondrial membrane depolarization/ultrastructural disruption; ↓ ATP production; ↑ superoxide	Alternative ribosome binders (preclinical); mitochondrial protectants (preclinical)
Oxidative amplification	∼6–24 h	Iron–AG complex formation; lipid peroxidation; GSH depletion	4-HNE adducts; protein carbonylation ↑; GSH:GSSG ratio ↓	Antioxidants; iron chelators; GSH precursors
Ion dysregulation	∼12–36 h	↑ intracellular Ca2+; altered membrane conductance and ion homeostasis; membrane permeabilization	Ca2+ waves; membrane potential changes; phospholipid scrambling	Ca2+ chelators; ion channel modulators
Cell death execution	∼24–72 h	Cytochrome c release; caspase activation; necroptosis activation; ferroptosis (iron-dependent lipid peroxidation)	TUNEL-positive nuclei; activated caspase-3; RIPK3/MLKL translocation; lipid peroxidation markers (e.g., 4-HNE)	Anti-apoptotic agents (preclinical); caspase inhibitors (preclinical); RIPK1 inhibitors (preclinical); ferroptosis inhibitors (preclinical)

Timeframes represent approximate, overlapping windows derived primarily from experimental (in vitro and animal) models and should not be interpreted as precise clinical kinetics. Values vary by dose, compound, species, and developmental stage. Interventions marked “preclinical” have not been validated in human clinical trials. Molecular markers represent commonly reported mechanistic features rather than universal or sequentially obligatory events. Stages may overlap and vary according to dose, compound, species, and developmental context. Arrows indicate direction of change (↑ increase; ↓ decrease).

Abbreviations: AG, aminoglycoside; ATP, adenosine triphosphate; Ca²⁺, calcium ion; GSH, reduced glutathione; GSSG, oxidized glutathione (glutathione disulfide); GSH: GSSG, ratio of reduced to oxidized glutathione; 4-HNE, 4-hydroxynonenal; MET, mechanoelectrical transduction; MLKL, mixed lineage kinase domain-like protein; RIPK1, receptor-interacting protein kinase 1; RIPK3, receptor-interacting protein kinase 3; ROS, reactive oxygen species; TRP, transient receptor potential; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling.