Blonanserin (Lonasen) is a relatively new atypical antipsychotic commercialized by Dainippon Sumitomo Pharma in Japan and Korea for the treatment of schizophrenia. Relative to many other antipsychotics, blonanserin has an improved tolerability profile, lacking side effects such as extrapyramidal symptoms, excessive sedation, or hypotension.

Blonanserin acts as a mixed 5-HT₂ (K_i = 3.98 nM) and D₂ receptor (K_i = 14.8 nM) antagonist and also exerts some blockade of α₁-adrenergic receptors (K_i = 56.3 nM). It lacks significant affinity for numerous other sites including the 5-HT_1A, 5-HT₃, D₁, α₂-adrenergic, β-adrenergic, H₁, and mACh receptors and the monoamine transporters, though it does possess low affinity for the sigma receptor (IC₅₀ = 286 nM).