What is the dosage for theophylline?
Theophylline may be taken with or without food but should not be
crushed or chewed. High blood theophylline levels can lead to symptoms of
toxicity (see below). Therefore, theophylline blood levels are monitored
periodically during treatment to assure achievement of optimal and safe levels.
The initial dose is 300-600 mg once daily or as a divided dose for 3 days. The
maintenance dose is 400-600 mg daily.
Which drugs or supplements interact with theophylline?
Certain groups of patients breakdown theophylline slowly, and can develop elevated blood levels and potential toxicity even on normal doses. These patients include those with liver disease, older men with chronic lung diseases, infants, patients with high fever or heart failure, and patients taking other medications that increase blood theophylline levels.
Examples of medications that can elevate theophylline blood levels include ephedrine, allopurinol (Zyloprim), cimetidine (Tagamet), ciprofloxacin (Cipro), clarithromycin (Biaxin), itraconazole (Sporanox), ketoconazole, erythromycin, oral contraceptives, fluvoxamine (Luvox), and propranolol (Inderal).
Theophylline toxicity can cause nausea, vomiting, insomnia, seizures, agitation and life- threatening heart rhythm abnormalities. St. John’s Wort, rifampin, and carbamazepine decrease levels of theophylline and potentially its effect by increasing its elimination. Theophylline may decrease levels and the effect of carbamazepine by increasing its elimination. Theophylline is metabolized mainly by the liver and dosages should be reduced in patients with liver dysfunction. On the other hand, theophylline is generally metabolized more rapidly in smokers (both tobacco and marijuana) and higher dosages may be required.