AKR1C1-IN-1 is a selective inhibitor of the AKR1C1 enzyme, which plays a role in steroid hormone metabolism and the regulation of intracellular levels of active androgens, estrogens, and progestins. It is primarily used in research settings to study hormone-dependent diseases, particularly those involving the prostate and breast. By inhibiting AKR1C1, this compound helps modulate the local concentration of bioactive steroids, making it a valuable tool in investigating conditions such as castration-resistant prostate cancer, where residual androgen signaling contributes to disease progression. It has also been explored for its potential in reducing the production of neuroactive steroids, suggesting possible applications in neurological disorders influenced by steroid imbalances. Due to its specificity, AKR1C1-IN-1 aids in dissecting the individual contributions of AKR1C isoforms in metabolic pathways, supporting the development of targeted therapies with fewer off-target effects. Its use remains confined to preclinical research, where it serves as a pharmacological probe to validate AKR1C1 as a therapeutic target.