Ketamine and esketamine are increasingly prescribed for treatment-resistant mood disorders and suicide risk, but ketamine is also misused. Analyzing reports in the World Health Organization pharmacovigilance database up to January 2024, ketamine showed elevated reporting odds ratios for alcohol abuse (3.24), substance dependence (12.48), substance use disorder (170.44), substance abuse (2.94), drug dependence (2.88), drug use disorder (11.54), and drug abuse (2.85). Esketamine had reduced odds for substance abuse (0.41), drug dependence (0.083), and drug abuse (0.052), and no increased odds for any alcohol or substance misuse parameter. These associations do not establish causation.
G protein-coupled receptors (GPCRs) are involved in many bodily processes. Traditional drug classification divides ligands into agonists or antagonists. Biased agonism is a newer concept where a drug selectively activates one intracellular signaling pathway over another, such as G protein versus β-arrestin pathways. This narrative review of literature up to April 2025 describes distinct mechanisms of antagonism and agonism beyond conventional models. Biased agonism has shown potential for greater efficacy, as with the incretin receptor agonist tirzepatide, and improved safety, as with certain serotonergic psychedelics and opioids. Preclinical evidence suggests biased agonism could improve psychiatric and neurological treatments by differentially activating pathways, pending clinical validation.