Niaprazine
Niaprazine
Sedative-hypnotic medication
Niaprazine (INN) (brand name Nopron) is a sedative-hypnotic drug of the phenylpiperazine group.[1][2] It has been used in the treatment of sleep disturbances since the early 1970s in several European countries including France, Italy, and Luxembourg.[3][4] It is commonly used with children and adolescents on account of its favorable safety and tolerability profile and lack of abuse potential.[5][6][7][8][9][10]
Originally believed to act as an antihistamine and anticholinergic,[11] niaprazine was later discovered to have low or no binding affinity for the H1 and mACh receptors (Ki = > 1 μM), and was instead found to act as a potent and selective 5-HT2A and α1-adrenergic receptor antagonist (Ki = 75 nM and 86 nM, respectively).[12] It possesses low or no affinity for the 5-HT1A, 5-HT2B, D2, and β-adrenergic, as well as at SERT and VMAT (Ki = all > 1 μM), but it does have some affinity for the α2-adrenergic receptor (Ki = 730 nM).[12]
Niaprazine has been shown to metabolize to the compound para-fluorophenylpiperazine (pFPP) in a similar manner to how trazodone and nefazodone metabolize to meta-chlorophenylpiperazine (mCPP).[13][14] It is unclear what role, if any, pFPP plays in the clinical effects of niaprazine.[12] However, from animal studies it is known that pFPP, unlike niaprazine, does not produce sedative effects, and instead exerts a behavioral profile indicative of serotonergic activation.[13]