terbutaline (Brethine)

Terbutaline is a member of a class of drugs called beta adrenergic receptor agonists (stimulators) that is used for treating asthma and other diseases of the airways. Other drugs in the same class of drugs include albuterol (Proventil), metaproterenol (Alupent), pirbuterol (Maxair), and salmeterol (Serevent). Asthma is a breathing problem caused by narrowing of air passages (bronchial tubes) through which air moves in and out of the lungs. These airways can be narrowed due to the accumulation of mucus, spasm of the muscles that surround them (bronchospasm), or swelling of their linings due to the accumulation of fluid. Airway narrowing leads to shortness of breath, wheezing, and cough. Terbutaline is a bronchodilator, a medication that dilates (expands) air passages in the lungs. It attaches to beta adrenergic receptors on muscles surrounding the air passages, causing the muscles to relax and dilate the air passages. Wider air passages allow more air to flow in and out of the lungs. Increased airflow reduces shortness of breath, wheezing, and cough. Terbutaline also is used for delaying premature labor by relaxing the muscles of the uterus that are responsible for expelling the fetus at the time of delivery. The FDA approved terbutaline in 1974.

What brand names are available for terbutaline?

Brethine, Bricanyl, Brethaire are no longer available in the U.S.

Is terbutaline available as a generic drug?

Yes

Terbutaline may cause side effects such as:

• tremor,
• nausea,
• nervousness,
• dizziness,
• headache,
• drowsiness,
• heartburn,
• heart palpitations,
• fast heart rate, and
• elevated blood pressure.

Vomiting, anxiety, restlessness, lethargy, excessive sweating, chest pain, and muscle cramping also may occur. Low blood potassium (hypokalemia) and high blood glucose have been associated with terbutaline.

The recommended adult oral dose for treating bronchospasm due to asthma, emphysema, or bronchitis is 2.5-5 mg 3 to 4 times daily approximately 6 hours apart while awake. The maximum dosage is 15 mg/day.

The recommended subcutaneous (under skin) dose is 0.25 mg every 15-30 minutes for two doses. The maximum dose is 0.5 mg within 4 hours.

The recommended dose for the inhaler is 2 puffs every 4 to 6 hours.

The dose for preterm labor is 2.5 to 10 mcg/min by intravenous infusion initially, then increase amounts every 10 to 20 minutes. The typical effective dose is 17.5 to 30 mcg/min. Treatment should not exceed 72 hours.

Combining terbutaline with thioridazine (Mellaril) may increase the occurrence of abnormal heart rhythms because both drugs can cause abnormal heart rhythms. The effects of terbutaline (a beta stimulant) are reversed by beta-blockers, for example, atenolol (Tenormin), nadolol (Corgard), propranolol (Inderal), and metoprolol (Lopressor). Conversely, terbutaline may reduce the effect of beta-blockers. Therefore, terbutaline and beta-blockers should not be used together.

Terbutaline reduces uterine contractions and may inhibit labor. There are no adequate studies of terbutaline in pregnant women.

Terbutaline is found in small amounts in the breast milk of nursing women. The American Academy of Pediatrics considers terbutaline to be compatible with breastfeeding.

What preparations of terbutaline are available?

Tablets: 2.5 and 5 mg. Injection: 1 mg/ml. Inhaler: 0.2 mg/puff. Nubulizer: 1 mg/ml.

How should I keep terbutaline stored?

Tablets and injection should be stored at room temperature, 15 C - 30 C (59 F - 86 F).