| Theophylline is one of the most commonly used | | | | specific adenosine antagonist, antagonizing A1, A2 and |
| medications for the treatment of the symptoms of | | | | A3 receptors almost equally. Theophylline is available |
| chronic asthma. It relaxes and opens air passages in | | | | in long-acting and short-acting forms. Long-acting |
| the lungs, making it easier to breathe. Its most | | | | theophylline, used daily to prevent chronic asthma, is |
| important actions are to prevent the signs and | | | | taken as an easy-to-remember, once-or-twice a day |
| symptoms of asthma, especially during the night, and | | | | dose. The use of theophylline is complicated by the |
| to reduce the need for cortisone type medication. It | | | | fact that it interacts with various drugs, chiefly |
| also reduces or prevents symptoms from triggers of | | | | cimetidine and phenytoin, and that it has a narrow |
| asthma such as exercise and allergens. It is a modest | | | | therapeutic index, so its use must be monitored to |
| bronchodilator relaxing muscles around the airway, | | | | avoid toxicity. It can also cause nausea, diarrhea, |
| allowing air to travel more freely in and out of the | | | | increase in heart rate, arrhythmias and CNS excitation. |
| lungs. Theophylline is 60% protein bound and has a | | | | Side Effects of Theophylline Drugs |
| distribution volume of 0.5 L/kg. Therapeutic serum | | | | 1. Nausea. |
| levels range from 10-20 mcg/mL. Toxic levels are | | | | 2. Vomiting. |
| considered to be higher than 20 mcg/mL. | | | | 3. Diarrhea, |
| Theophylline affects the cardiovascular (CV), | | | | 4. Headaches. |
| neurological, GI, and metabolic systems. The main | | | | 5. Irritability. |
| mechanism of action of theophylline is that of | | | | 6. Flushing. |
| adenosine receptor antagonism. Theophylline is a non | | | | 7. Palpitations. |