The Chemistry of Fentanyl and Its Implications on Brain Development: A Review

Since its discovery in 1960 by Paul Janssen, fentanyl has emerged as one of the central substances in the global opioid crisis because of its high potency (50–100 times that of morphine) and rapid penetration through the blood-brain barrier. Following the PRISMA 2020 guidelines for reporting systematic reviews and meta-analyses, this systematic review synthesizes the results of ten empirical studies (2018–2025) analyzing fentanyl's chemical characteristics and neurodevelopmental effects. The findings demonstrate that fentanyl disrupts synaptic development through µ-opioid receptor (MOR) agonism, induces neuronal apoptosis via oxidative stress pathways, alters gene expression in reward circuits, and produces lasting cognitive deficits. After perinatal exposure, preclinical studies have revealed persistent dysfunction of the somatosensory system and transcriptomic alterations in the nucleus accumbens. Clinical meta-analyses have demonstrated that children exposed to such chemicals suffer from serious cognitive and motor impairments. This review addresses the critical gap in integrating the specific molecular chemistry of fentanyl, its phenylpiperidine structure (C₂₂H₂₈N₂O), lipophilicity (logP ~ 4.0), and high receptor affinity with neurodevelopmental mechanisms. Future research should focus on computational chemistry approaches to design safer analogs and neuroprotective strategies. This study contributes to Sustainable Development Goal 3 (Target 3.5) by providing an evidence base for chemistry-informed harm reduction and prevention strategies.