Examples

Generic Name	Brand Name
ritodrine	Yutopar
terbutaline

Ritodrine and terbutaline are sometimes used as tocolytic medications to slow uterine contractions during preterm labor. Ritodrine and terbutaline are given through a vein (intravenously, or IV) and/or by injection.

Use of terbutaline for the treatment of preterm labor is an unlabeled use of the medication. Terbutaline has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of asthma and other breathing conditions, but it is also widely used to treat preterm labor.

The longer ritodrine and terbutaline are used, the less effective they are at stopping contractions (an effect called tachyphylaxis).

How It Works

Ritodrine and terbutaline can relax smooth muscles, like the uterus. These medications also affect the smooth muscles of the blood vessels and the small airways of the lungs.

Why It Is Used

Ritodrine or terbutaline can be used during preterm labor when:

• Labor needs to be delayed for 24 to 48 hours to:
  • Let corticosteroids, given to the mother, help fetal lungs mature.
  • Provide time to move a mother to a hospital that provides neonatal intensive care, if her local hospital does not.
• Regular uterine contractions have thinned (effaced) the cervix less than 80% and opened (dilated) it less than 4 cm, and the mother's amniotic sac has not broken.
• The mother is healthy.
• The fetus is alive and not in distress.

Depending on the medical facility, ritodrine or terbutaline may be the first medication used to delay premature birth.

How Well It Works

Both ritodrine and terbutaline are considered equally effective when labor needs to be delayed for 24 to 48 hours. But they usually do not completely stop contractions. Nor have they been shown to lower risks for the premature baby. ^{1 2}

Side Effects

Side effects are common with ritodrine and terbutaline use and may affect both the mother and fetus. Side effects can include:

• A nervous and/or shaking feeling and anxiety.
• A racing heartbeat or palpitations. These medications should not be used for women with known heart conditions.
• Chest pain or tightness. If this occurs, let a health professional know immediately.
• Nausea, vomiting, or both.
• Headache.
• Low blood pressure.
• Fever.
• Increased blood sugar (glucose) levels. These medications should not be used for women with poorly controlled diabetes or thyroid conditions.
• Decreased blood potassium levels. This can cause heart problems and muscle spasms in the legs.
• Fluid collecting in the lungs (pulmonary edema), a rare but life-threatening problem that is most common with women in premature labor who also have an infection. During ritodrine or terbutaline treatment, fluids are often limited to prevent this condition.
• Hallucinations.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If ritodrine or terbutaline treatment is effective, its effect typically lasts no more than 48 hours. Long-term treatment is not advised (based on the risk of serious side effects), nor is it effective. ¹

• Both ritodrine and terbutaline are sometimes harmful to the mother. The risks of treatment must be weighed against the benefit of delaying birth.
• Both medications can greatly increase the mother's and fetus's pulse. The mother must have her blood pressure and pulse checked frequently during the first few hours of treatment.
• Ritodrine is expensive compared with other tocolytic medications used to treat preterm labor. It is the only medication approved by the FDA for the treatment of preterm labor.

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Citations

1. Cunningham FG, et al. (2005). Preterm birth. In Williams Obstetrics, 22nd ed., pp. 855–880. New York: McGraw-Hill.

2. Haas DM (2005). Preterm birth, search date June 2005. Online version of Clinical Evidence (14): 1–20.