Ritodrine

Clinical data
Pronunciation	/ˈraɪtoʊdriːn/ RY-toh-dreen
AHFS/Drugs.com	Micromedex Detailed Consumer Information
Routes of administration	Oral (tablets), parenteral (IV)
ATC code	G02CA01 (WHO)
Legal status
Legal status	US: Discontinued
Pharmacokinetic data
Protein binding	~56%
Metabolism	Hepatic, metabolites are inactive[1]
Elimination half-life	1.7–2.6 hours
Identifiers
IUPAC name 4-[2-[[(1R,2S)-1-hydroxy-1-(4-hydroxyphenyl)propan-2-yl]amino]ethyl]phenol
CAS Number	26652-09-5 Y
PubChem CID	33572
IUPHAR/BPS	7294
DrugBank	DB00867 Y
ChemSpider	30971 Y
UNII	I0Q6O6740J
KEGG	D02359 Y
ChEMBL	ChEMBL785 Y
CompTox Dashboard (EPA)	DTXSID7048534
ECHA InfoCard	100.043.512
Chemical and physical data
Formula	C17H21NO3
Molar mass	287.359 g·mol−1
3D model (JSmol)	Interactive image
SMILES O[C@H](c1ccc(O)cc1)[C@@H](NCCc2ccc(O)cc2)C
InChI InChI=1S/C17H21NO3/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/t12-,17-/m0/s1 Y Key:IOVGROKTTNBUGK-SJCJKPOMSA-N Y
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Ritodrine (trade name Yutopar) is a tocolytic drug used to stop premature labor.^[2] This drug has been removed from the US market, according to FDA Orange Book. It was available in oral tablets or as an injection and was typically used as the hydrochloride salt, ritodrine hydrochloride.

Mechanism

Ritodrine is a short-acting β₂ adrenoreceptor agonist — a class of medication used for smooth muscle relaxation (other similar drugs are used in asthma or other pulmonary diseases such as salbutamol (albuterol)). Since ritodrine has a bulky N-substituent, it has high β₂ selectivity. Also, the 4-hydroxy group on the benzene ring is important for activity as it is needed to form hydrogen bonds. However, the 4-hydroxy group makes it susceptible to metabolism by catechol-O-methyl transferase (COMT). Since it is β₂-selective it is used for premature labor.^[3]

Side effects and potential contraindications

Most side effects of β₂ agonists result from their concurrent β₁ activity, and include increase in heart rate, rise in systolic pressure, decrease in diastolic pressure, chest pain secondary to myocardial infarction, and arrhythmia. Beta agonists may also cause fluid retention secondary to decrease in water clearance, which when added to the tachycardia and increased myocardial work, may result in heart failure. In addition, they increase gluconeogenesis in the liver and muscle resulting in hyperglycemia, which increases insulin requirements in diabetic patients. The passage of β agonists through the placenta does occur and may be responsible for fetal tachycardia, as well as hypoglycemia or hyperglycemia at birth.

Patients with type 2 diabetes, high blood pressure or migraines should bring this to their doctor's attention before receiving care.

It has also been associated with postpartum bleeding.^{[citation needed]}