[4] Adverse effects may include sedation, drowsiness, heartburn, and thickening of bronchial secretions.

[5] The precise mechanism of action of cloperastine is not fully clear, but several different biological activities have been identified for the drug, of which include: ligand of the σ1 receptor (Ki = 20 nM) (likely an agonist),[6] GIRK channel blocker (described as "potent"),[7][8][9][10] antihistamine (Ki = 3.8 nM for the H1 receptor),[3][6] and anticholinergic.

[3][11] It is thought that the latter two properties contribute to side effects, such as sedation and somnolence, while the former two may be involved in or responsible for the antitussive efficacy of cloperastine.

[6][7] The halogenation of 4-Chlorobenzhydrol [119-56-2] (1) with phosphorus tribromide in tetrachloromethane gives 1-(Bromophenylmethyl)-4-chlorobenzene [948-54-9] (2).

Reaction with piperidine (5) completes the synthesis of Cloperastine (6).