Niaprazine is a histamine H1-receptor antagonist. Niaprazine has antihistamine and antiserotonin activity and has been utilized in the research of sleep disorders.

Physicochemical Properties

Molecular Formula	C20H25FN4O
Molecular Weight	356.44
Exact Mass	356.201
CAS #	27367-90-4
Related CAS #	34426-53-4 (tri-hydrochloride)
PubChem CID	71919
Appearance	White to off-white solid powder
LogP	3.129
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	5
Rotatable Bond Count	6
Heavy Atom Count	26
Complexity	434
Defined Atom Stereocenter Count	0
InChi Key	RSKQGBFMNPDPLR-UHFFFAOYSA-N
InChi Code	InChI=1S/C20H25FN4O/c1-16(23-20(26)17-3-2-9-22-15-17)8-10-24-11-13-25(14-12-24)19-6-4-18(21)5-7-19/h2-7,9,15-16H,8,10-14H2,1H3,(H,23,26)
Chemical Name	N-[4-[4-(4-fluorophenyl)piperazin-1-yl]butan-2-yl]pyridine-3-carboxamide
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	Niaprazine has minimal affinity for D2, α2, β, H1, and mAch receptors as well as the vesicular monoamine transporter. 5-HT1A and 5-HT1B binding sites do not recognize niaprazine well, while α1 (Ki = 77 nM) and 5-HT2 (Ki = 25 nM) binding sites do[2]. Niaprazine, in particular, the (+)stereoisomer, has a higher affinity for these sites.
ln Vivo	Rat brain 5-hydroxyindole acetic acid (5-HIAA) concentrations rise 30 minutes after niaprazine (60 mg/kg; ip; once) administration and fall 3–8 hours later. Moreover, niaprazine causes a transient reduction in dopamine (DA) and noradrenaline (NA) in rat brains[3].
Animal Protocol	Animal/Disease Models: Male SD (Sprague-Dawley) rats (150-200 g)[3] Doses: 60 mg/kg Route of Administration: intraperitoneal (ip) injection; once Experimental Results: Increased rat brain 5-hydroxyindole acetic acid (5-HIAA) concentrations 30 min after treatment, and decreased them at 3-8 hr after treatment.
References	[1]. Molecular pharmacology of niaprazine. Prog Neuropsychopharmacol Biol Psychiatry. 1988;12(6):989-1001. [2]. Niaprazine in the treatment of autistic disorder. J Child Neurol. 1999 Aug;14(8):547-50. [3]. The effect of niaprazine on the turnover of 5-hydroxytryptamine in the rat brain. Neuropharmacology. 1982 Feb;21(2):163-9.
Additional Infomation	Niaprazine is a member of piperazines. Niaprazine is a selective brain catecholamine depletor.

Solubility Data

Solubility (In Vitro)

DMSO: 100 mg/mL (280.55 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 0.83 mg/mL (2.33 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 8.3 mg/mL clear DMSO stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: 0.83 mg/mL (2.33 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 8.3 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 0.83 mg/mL (2.33 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 8.3 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.8055 mL	14.0276 mL	28.0552 mL
	5 mM	0.5611 mL	2.8055 mL	5.6110 mL
	10 mM	0.2806 mL	1.4028 mL	2.8055 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.