Ritodrine (trade name Yutopar) is a
tocolytic
Tocolytics (also called anti-contraction medications or labor suppressants) are medications used to suppress premature labor (from Greek τόκος ''tókos'', "childbirth", and λύσις ''lúsis'', "loosening"). Preterm birth accounts for 70% ...
drug
A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...
used to stop
premature labor
Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between 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
In chemistry, a hydrochloride is an acid salt resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base (e.g. an amine). An alternative name is chlorhydrate, which comes from French. An archaic alternative na ...
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
, 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
Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...
(albuterol)). Since ritodrine has a bulky ''N''-substituent, it has high β
2 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 β
2-selective it is used for premature labor.
Medicinal Chemistry of Adrenergics and Cholinergics
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
Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (su ...
and increased myocardial
Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that ...
work, may result in heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...
. In addition, they increase gluconeogenesis
Gluconeogenesis (GNG) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. It is a ubiquitous process, present in plants, animals, fungi, bacteria, and other microorganisms. In vertebrat ...
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
Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, ...
, high blood pressure
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
or migraine
Migraine (, ) is a common neurological disorder characterized by recurrent headaches. Typically, the associated headache affects one side of the head, is pulsating in nature, may be moderate to severe in intensity, and could last from a few hou ...
s should bring this to their doctor's attention before receiving care.
It has also been associated with postpartum bleeding
Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume fo ...
.
References
{{Adrenergic agonists
Beta2-adrenergic agonists
Phenols
Phenylethanolamines
Substituted amphetamines
Tocolytics