GENERIC NAME: terbutaline
DRUG CLASS AND MECHANISM: Terbutaline is a bronchodilator, a medication that dilates the air passages in the lungs. It attaches to receptors on the muscle cells lining the air passages (beta adrenergic receptors ) causing the muscles to relax, and in so doing it increases the diameter of the air passages so that more air can flow in and out of the lungs during breathing. Terbutaline also relaxes some other types of smooth muscles, such as the muscles of the uterus; however, other types of muscle may be stimulated to contract rather than relax. Terbutaline was first approved by the FDA in 1974

PRESCRIPTION: yes

GENERIC AVAILABLE: yes

PREPARATIONS: Tablets: 2.5 mg, 5 mg. Inhalant: 0.2 mg/spray.

STORAGE: Tablets and inhaler should be stored between 2° (36°F) and 30°C (86°F) in a dry place.

PRESCRIBED FOR: Terbutaline is used to relieve and prevent attacks of asthma, including exercise-induced asthma. Asthma is a breathing problem caused by narrowing of the air passages (bronchial tubes) that allow air to move in and out of the lungs. These airways can be narrowed due to the accumulation of mucus, spasm of the muscles that surround them, or swelling of their linings due to the accumulation of fluid. Airway narrowing leads to shortness of breath, wheezing, and cough. Terbutaline dilates bronchial airways by relaxing the surrounding bronchial muscles. Terbutaline also can be helpful in patients with emphysema and chronic bronchitis when symptoms are partially caused by spasm of the muscles of the air passages. Terbutaline also is used for delaying premature labor by relaxing the uterine muscles that are responsible for expelling the fetus at delivery. The inhaled form of terbutaline starts working within 15 minutes and can last up to 6 hours.

DOSING:

Oral: Terbutaline is most frequently given every six to eight hours. For persons with difficulty swallowing, the tablets may be crushed and mixed with food or fluids.

Inhalation: Terbutaline may be inhaled every 4 to 8 hours. In patients with asthmatic attacks brought about by exercise or other forms of exertion, terbutaline can be used as two puffs taken at least 10-15 minutes prior to beginning exercise. To avoid the spread of infection, only one person should use each inhaler. For any inhaler, the following steps should be followed:

1、shake inhaler

2、exhale fully

3、tilt head up slightly

4、place lips around the inhaler

5、squeeze down the release and begin to inhale slowly and completely

6、hold breath, if possible, for 10 seconds

7、repeat, if instructed to do so, after at least 1 to 2 minutes

DRUG INTERACTIONS: The effects of terbutaline on the heart and blood vessels may be increased by the use of tricyclic antidepressants (TCAs) such as amitriptyline (Elavil), imipramine (Tofranil), or desipramine (Norpramin), or maprotiline (Ludiomil), or any of the MAO (mono-amine oxidase) inhibitor-class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane).

The effects of terbutaline (a beta stimulant) are reversed by beta-blockers, e.g. atenolol (Tenormin), nadolol (Corgard), propranolol (Inderal), metoprolol (Lopressor) and vice versa. Therefore, terbutaline and beta-blockers should not be used together. Blood pressure and pulse may increase during treatment with terbutaline because of the stimulant effects of terbutaline on muscles of the heart and blood vessels.

The use of terbutaline with digoxin (Lanoxin) or with levodopa (found in Sinemet) may increase the risk of developing heart arrhythmias.

Thyroid hormones (e.g. levothyroxine, Synthroid), like terbutaline, can stimulate the heart. This combination may be of special concern in patients with preexisting heart disease.

PREGNANCY: Terbutaline reduces uterine contractions and may inhibit labor; unless it is used specifically for this purpose, it should be used cautiously during the second and third trimesters of pregnancy. Terbutaline is otherwise considered safe during pregnancy.

NURSING MOTHERS: Terbutaline is found in small amounts in the breast milk of nursing women that use it. The American Academy of Pediatrics considers terbutaline to be compatible with breast- feeding.

SIDE EFFECTS: Terbutaline can cause side effects including palpitations, fast heart rate, elevated blood pressure, tremor, nausea, nervousness, dizziness, and heart burn. Throat irritation and nose bleeds can also occur with the inhaled preparation. Other, less common side effects include headache, nausea/vomiting, anxiety, restlessness, lethargy, drowsiness, excessive sweating, and muscle cramping. Like other beta adrenergic stimulants, terbutaline may cause chest pain, taste alterations and dry mouth.