Ritodrine HCl (DU21220; DU21220; ST51015115; ST-51015115; Pre-Par; Utopar), the hydrochloride salt of ritodrine, is a β-2 adrenergic receptor agonist used to treat premature labor.

Physicochemical Properties

Molecular Formula	C17H22CLNO3
Molecular Weight	323.81
Exact Mass	323.128
Elemental Analysis	C, 63.06; H, 6.85; Cl, 10.95; N, 4.33; O, 14.82
CAS #	23239-51-2
Related CAS #	Ritodrine; 26652-09-5; Ritodrine-d3 hydrochloride
PubChem CID	3040551
Appearance	White to off-white solid powder
Density	1.213 g/cm3
Boiling Point	512.3ºC at 760 mmHg
Melting Point	192-196ºC
Flash Point	175.6ºC
Vapour Pressure	2.55E-11mmHg at 25°C
LogP	3.544
Hydrogen Bond Donor Count	5
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	6
Heavy Atom Count	22
Complexity	284
Defined Atom Stereocenter Count	2
SMILES	Cl[H].O([H])[C@]([H])(C1C([H])=C([H])C(=C([H])C=1[H])O[H])[C@]([H])(C([H])([H])[H])N([H])C([H])([H])C([H])([H])C1C([H])=C([H])C(=C([H])C=1[H])O[H]
InChi Key	IDLSITKDRVDKRV-XHXSRVRCSA-N
InChi Code	InChI=1S/C17H21NO3.ClH/c1-12(17(21)14-4-8-16(20)9-5-14)18-11-10-13-2-6-15(19)7-3-13;/h2-9,12,17-21H,10-11H2,1H3;1H/t12-,17-;/m0./s1
Chemical Name	4-[2-[[(1R,2S)-1-hydroxy-1-(4-hydroxyphenyl)propan-2-yl]amino]ethyl]phenol;hydrochloride
Synonyms	DU21220; Ritodrine Hydrochloride; Ritodrine (hydrochloride); (+-)-Ritodrine hydrochloride; DU21220; DU21220; ST51015115; ST-51015115; Pre-Par; Utopar
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 Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.
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

Targets	β2-adrenergic receptor
ln Vivo	Background: Beta-adrenergic agonists are commonly used to arrest premature labor. Although treatment of preterm labor with these agents can delay delivery by 24 to 48 hours, the potential risks and benefits to the mother and infant before and after delivery have not been adequately assessed. Methods: We randomly assigned 708 women with preterm labor at six hospitals to receive an intravenous infusion of either the beta-adrenergic agonist ritodrine (n = 352) or placebo (n = 356). Assignment was made with stratification according to four categories of gestational age (20 to 23 weeks, 24 to 27 weeks, 28 to 31 weeks, and 32 to 35 weeks). The primary objective was to assess the effect of ritodrine on perinatal mortality. Secondary objectives were the evaluation of the causes of perinatal death, the extent to which delivery was delayed with ritodrine, and the effects on birth weight, maternal morbidity, neonatal morbidity, and infant morbidity at 18 months of postnatal age, corrected for preterm delivery. Results: Among the 771 infants born to the women in the study (including 63 pairs of twins), there were 23 deaths (6.1 percent) in the ritodrine group and 25 deaths (6.4 percent) in the placebo group (event-rate difference, -0.3 percent; 95 percent confidence interval, -3.7 percent to 3.1 percent). There was no difference between the groups in the extent of delay of delivery, the incidence of delivery before 37 weeks' gestation, the proportion of babies weighing less than 2500 g, or measures of neonatal morbidity. Maternal morbidity (such as chest pain and cardiac arrhythmias) occurred more frequently but not exclusively in the ritodrine group. One infant born to a woman in the ritodrine group and five infants born to women in the placebo group had cerebral palsy (P = 0.09). There was a slight but not significant trend toward an improved score on the Bayley Psychomotor Development Index at 18 months of age among the infants of the ritodrine-treated women. Conclusions: We found that the use of ritodrine in the treatment of preterm labor had no significant beneficial effect on perinatal mortality, the frequency of prolongation of pregnancy to term, or birth weight.[1]
References	[1]. Treatment of premature labor with ritodrine: a randomized controlled study. Obstet Gynecol. 1979 Aug;54(2):220-3. [2]. Treatment of preterm labor with the beta-adrenergic agonist ritodrine. N Engl J Med. 1992 Jul 30;327(5):308-12. [3]. Ritodrine in the treatment of preterm labour: a meta-analysis. Indian J Med Res, 2005. 121(2): p. 120-7.
Additional Infomation	Ritodrine Hydrochloride is the hydrochloride salt form of ritodrine, a phenethylamine derivative with tocolytic activity. Ritodrine hydrochloride binds to and activates beta-2 adrenergic receptors of myocytes in the uterine myometrium, which results in decreased intensity and frequency of uterine contraction. Specifically, ritodrine hydrochloride probably activates adenyl cyclase, thereby increasing production of cyclic adenosine monophosphate (cAMP), which in turn enhancing the efflux of calcium from vascular smooth muscle cells. A lack of intracellular calcium prevents uterine myometrial contraction. In addition, this agent may directly inactivate myosin light chain kinase, a critical enzyme necessary for the initiation of muscle contractions. An adrenergic beta-2 agonist used to control PREMATURE LABOR.

Solubility Data

Solubility (In Vitro)

DMSO: 65~120 mg/mL (200.7~370.6 mM) Water: ~65 mg/mL (~200.7 mM) Ethanol: ~65 mg/mL

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 1.71 mg/mL (5.28 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 17.1 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL 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: ≥ 1.71 mg/mL (5.28 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in 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 17.1 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: ≥ 1.71 mg/mL (5.28 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 17.1 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. Solubility in Formulation 4: 50 mg/mL (154.41 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	3.0882 mL	15.4412 mL	30.8823 mL
	5 mM	0.6176 mL	3.0882 mL	6.1765 mL
	10 mM	0.3088 mL	1.5441 mL	3.0882 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.