Bronchospasm is a sudden constriction in the terminal airways of the lungs, resulting from the contraction of smooth muscles in the walls of the bronchi. The narrowing of the bronchi is the major pathological feature that constitutes an asthma attack. The constriction of the smooth muscles of the bronchi occurs due to a variety of triggers that elicit an allergic reaction causing the inflammatory cells, called the mast cells, to release allergic mediators, namely histamine and leukotrienes. Bronchospasm drug treatment is focused on counteracting these pathological processes.
Beta-adrenergic Agonists
The Merck Manual Online Medical Library notes that class beta 2 adrenergic agonists are the drugs considered the mainstay treatment for bronchospasms and asthma. This is because they relax the smooth muscles and prevent the release of the inflammatory mediators from the mast cells. The relaxation of the bronchi is achieved through binding with a beta 2 adrenergic receptor on the walls where adrenaline normally exerts its effects, causing relaxation of the walls and increasing the caliber of the bronchi. Beta 2 receptor agonists are available in short and long-acting preparations. Patients prone to repeated attacks of bronchospasm, like asthma patients, benefit from inhalation of a long-acting beta 2 agonist daily.
Anti-Cholinergics
According to the Merck Manual Online Medical Library, anti-cholinergics, also used in the treatment of bronchospasm, are drugs that block the receptors responsible for the parasympathetic tone, or the narrowing, on the bronchial wall. These receptors are called the muscarinic, or M3, receptors. The most commonly used anti-cholinergic is called ipratropium, which is used extensively for its bronchial-relaxing affect in patients with obstructive lung disease such as chronic bronchitis and emphysema. The use of anti-cholinergics may be complicated by blurry vision, dry mouth, dilation of the pupil, headache, slight sedation, increase in the heart rate and skin flushing.
Methylxanthines
MayoClinic.com notes that theophylline, a methylxanthine, is a medication, which relaxes the bronchi and relieves bronchospasm. Methylxanthines are used for control of long-term bronchospasm. Prescribing theophylline as a once- a-day pill was once popular, but gradually fell out of favor over time because of its adverse effects like seizures and disturbances in cardiac rhythm. They also cause unfavorable reactions with many other drugs, such as macrolide antibiotics.
