Drug Comparisons

Like inhaled beta-2 agonists, oral beta-2 agonists activate certain receptors in the lungs. Receptors are specialized places on cells that recognize and attract specific substances that activate the receptors. Activating beta-2 receptors relaxes muscles in the bronchial tubes (airways) and lets more air enter the lungs.

For patients with mild asthma, inhaled beta-2 agonists are typically first-line agents. Short-acting inhaled beta-2 agonists are used more frequently than oral forms of beta-2 agonists because the inhaled products generally provide faster relief, they usually have fewer adverse effects, and they typically are more effective. However, oral beta-2 agonists can be prescribed for patients who cannot use an inhaler or who need prolonged symptom relief (such as during the night).

Drugs in this Class
Albuterol Oral Syrup
Albuterol Oral Tablets
Metaproterenol Tablets
Terbutaline Tablets

Summarizing the Evidence

• Only a few small studies have compared oral forms of albuterol, metaproterenol, and terbutaline with each other. Mostly conducted several years ago, the studies do not reach firm conclusions about which oral beta-2 agonist may be better than the others. In general, all oral beta-2 agonists are about equally as effective in treating asthma symptoms.
• One study showed that oral metaproterenol was quicker to provide relief of asthma symptoms, but that oral albuterol and oral terbutaline controlled asthma symptoms for longer periods.
• Metaproterenol is used less often than albuterol because albuterol is more selective for beta-2 receptors and may be less likely to cause cardiac side effects than metaproterenol.
• Because they are absorbed systemically (through the bloodstream) rather than going directly to the lungs like inhaled beta-2 agonists do, oral beta-2 agonists have more side effects than inhaled beta-2 agonists.
• Generally, oral beta-2 agonists have not been as effective as extended-release theophylline for controlling nocturnal (nighttime) asthma symptoms.

Dosing and Administration

• Albuterol, metaproterenol, and terbutaline are available in immediate-release (short-acting) formulations. Albuterol is also available in an extended-release (long-acting) preparation.
• Short-acting oral beta-2 agonists can be used for relief of acute asthma symptoms.
• Compared to inhaled beta-2 agonists, the doses of oral beta-2 agonists needed to control asthma symptoms are relatively higher.
• Short-acting oral albuterol and metaproterenol are available as tablets or syrup, commonly taken three times or four times daily. Oral terbutaline comes in tablets that usually are taken three times daily.
• Long-acting formulations of albuterol (marketed as the brand-name products Proventil Repetabs, Volmax, and VoSpire) come as tablets to be taken twice a day. They cannot be used for immediate relief of asthma symptoms. Typically, they are used for long-term prevention of symptoms, especially asthma symptoms that occur at night.

Generic Availability

• Short-acting albuterol, metaproterenol, and terbutaline are all available as generics.
• Long-acting albuterol is also available as a generic.

Drug Interactions

Some interactions between medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how the drugs interact and the severity of the interaction, please use our Drug Interactions Checker.

Side Effects

To view specific side effect information, please use our Side Effect Checker.

Additional Information

References

Drug Facts & Comparisons. Facts and Comparisons. St. Louis, MO. 2002.

Drugdex Database. In: Gelman CJ, Rumack BH, editors. Denver: Micromedex Inc. 2000.

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U.S. National Institutes of Health. National Heart, Lung, and Blood Institute. Global Initiative for Asthma. Global strategy for asthma management and prevention. Revised 2002. NIH Publication No. 02-3659. February 2002.

Van Keimpema AR, Ariaansz M, Raaijmakers JA, Nauta JJ, Postmus PE. Treatment of nocturnal asthma by addition of oral slow-release albuterol to standard treatment in stable asthma patients. J Asthma. 1996;33(2):119-124.

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Wolfe JD, Shapiro GG, Ratner PH. Comparison of albuterol and metaproterenol syrup in the treatment of childhood asthma. Pediatrics. 1991;88(2):312-319.

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Last Updated: September 2008
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