Theophylline is a prescription medication generally used to treat symptoms of asthma, bronchitis, and emphysema. It typically works by widening the airway passages in the lungs, thereby allowing air to move more freely with each breath. The drug also strengthens the diaphragm and the right section of the heart. It is available in several forms including syrups, solutions, capsules, and tablets.
The medication was discovered by Albrecht Kossel in 1888 during a chemical extraction of tea leaves. It was initially used as a diuretic before research established it as a smooth muscle relaxant. By the 1930s, the medication was commonly used to treat asthma.
Theophylline is a potent inhibitor of phosphodiesterase and blocks the actions of the adenosine receptor. Clinical studies of the drug show that it can usually reverse steroid insensitivity in smokers and individuals with chronic obstructive pulmonary disorder (COPD). It also has the ability to reduce the effects of oxidative stress from free radicals and peroxides.
The cellular activities of theophylline typically cause the smooth muscles in the bronchi and bronchioles to relax and the heart muscle contractions to strengthen. This generally leads to an increase in blood pressure, heart rate, and airflow in the lungs. Some people may experience side effects after taking theophylline, such as nausea, vomiting, diarrhea, headaches, and palpitations. More serious complications include seizures and an irregular heart rhythm.
Theophylline can interact with other medications, including ciprofloxacin, ephedrine, cimetidine, allopurinol, and erythromycin. Typically, these drugs will increase the concentration of theophylline in the blood and cause side effects. The potential for an elevated theophylline level is a concern for people with liver disease, lung disease, or heart failure. Additionally, foods and drinks that contain caffeine, such as chocolate, coffee, tea, and cocoa, may increase the side effects of the drug.
Generally, the dosage depends on how well the body metabolizes the drug. People with liver disease cannot metabolize the drug effectively, so they require a smaller dose. Smokers metabolize the drug much quicker than non-smokers, so they typically require a higher dose. The tablet or capsule can be an extended-release form that is designed to deliver a specific amount of the drug into the bloodstream over a period of time. Blood tests are generally used to ensure that a safe level of theophylline is present in the blood.