Terbutaline in Pregnancy

Terbutaline Sulfate, which is also known by its brand names Brethaire, Brican, Bricar, Bricyn, Terbutalina, Terbutalino, among others, is an asthma drug in the class of beta-adrenergics that is approved by the FDA. Its use is to prevent asthma attacks as well as treat bronchitis and emphysema. It works by relaxing the bronchial tubes and soothing asthma symptoms.

When to Use Terbutaline in Pregnancy

Dr. Fink of Pregnancy Today says that there was a medication known as ritodrine back in the 1980s that was approved by the FDA as a labor-inhibiting drug. It is no longer on the market. Because terbutaline is similar, terbutaline is used in the event of preterm labor to help relax uterine muscles and stop contractions. The drug is believed to relax the uterine muscles which slow contractions. Preterm labor usually consists of contractions with changes to the cervix like effacement and dilation before full term. Terbutaline is not FDA approved for such a purpose but is used “off-label” by doctors to control labor occurring preterm.

Dose and Usage

The usage, according to medscape.com, is:

(Off Label) Preterm Labor

  • Start at 2.5-5 mcg/min IV
  • Gradually increase as tolerated at 20-30 minute intervals
  • Effective dose is between 17.5-30 mcg/min IV, but doses of up to 70-80 mcg/min can be required
  • Continue use for 12 hours after the uterine contractions cease; do not exceed 48-72 hours
  • Prolonged IV use is not recommended

Does Terbutaline Work?

Studies have shown the drug to be effective for 24 to 48 hours. These studies also show that it is not any better than a placebo in prolonging pregnancy beyond that amount of time. Other studies have shown it to be an effective tocolytic. Terbutaline was been anecdotally successful.

Is It Safe to Use Terbutaline in Pregnancy?

No, it’s probably not. There are some significant risks that come with its usage. There have been maternal deaths associated with the use of terbutaline for prevention and treatment of preterm labor. The FDA issued a safety announcement on February 17, 2011 that clinicians should cease the usage of injectable terbutaline in pregnancy as a treatment for preterm labor beyond 48 to 72 hours because of the risks of maternal heart problems and death. Additionally, oral terbutaline shouldn’t be used for preterm labor because it has the same risks as the injectable version and is not proven to be effective.

Animal studies have found harmful effects to the unborn baby due to the usage of terbutaline. It has not been fully studied in humans so it is worth noting that animals do not always respond to medications the same that humans do. The extent of risks of using terbutaline during pregnancy isn’t known. A Category B pregnancy medication should only be given to a pregnant woman only in the case that the benefits to the patient outweigh the possible risks to the baby.

What Are the Precautions and Possible Side Effects?

Precautions

  • If you are allergic to terbutaline or any other medications or their ingredients tell your doctor.
  • Make sure to tell your doctor and pharmacist about any prescription, nonprescription drugs, vitamins, and supplements you are taking.
  • Tell your doctor if you have ever had high blood pressure, an irregular heartbeat, heart disease, diabetes, an overactive thyroid gland, or seizures.
  • The risks of severe side effects increased with the dosage.

Side Effects

The most common side effects of terbutaline are:

  • tremors
  • increased heart rate
  • jitteriness

Many of the other side effects are not as common. If you do experience any of these symptoms, you should contact your doctor immediately. Because of certain risks of terbutaline in pregnancy you should also be screened for preexisting conditions.

Mild Adverse Effects

  • Infrequently: restlessness, dizziness, headache, drowsiness, insomnia
  • Infrequent to Frequent: increased sweating, rapid and pounding heartbeat, muscle cramps in limbs
  • Frequent with IV, rare with oral form: heartburn, nausea, vomiting
  • Frequent: increased blood sugar

Serious Adverse Effects

  • Infrequent: rapid or irregular heart rhythm, increased blood pressure, intensification of angina, increased blood sugar
  • Possible, especially wth IV: lowered blood calcium or potassium
  • Case Reports: liver toxicity, severe lowering of blood pressure
  • Rare Reports: seizures
 
 
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