Chlorprothixene HCl is the hydrochloride salt form of chlorprothixene, a typical antipsychotic drug of the thioxanthene (tricyclic) class. It exerts strong blocking effects by blocking the 5-HT2 D1, D2, D3, histamine H1, muscarinic and alpha1 adrenergic receptors. Chlorprothixene HCl is the hydrochloride salt form of chlorprothixene, a typical antipsychotic drug of the thioxanthene (tricyclic) class. It exerts strong blocking effects by blocking the 5-HT2 D1, D2, D3, histamine H1, muscarinic and alpha1 adrenergic receptors.