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(theophylline, anhydrous) Capsule, Extended Release



Theophylline is structurally classified as a methylxanthine. It occurs as a white, odorless, crystalline powder with a bitter taste. Anhydrous theophylline has the chemical name 1H-Purine-2,6-dione, 3,7-dihydro-1,3-dimethyl-, and is represented by the following structural formula:

THEO-24 (theophylline) Structural Formula Illustration

The molecular formula of anhydrous theophylline is C7H8N4O2 with a molecular weight of 180.17.

Theo-24 (theophylline anhydrous capsule) ® is available as capsules intended for oral administration, containing 100 mg, 200 mg, 300 mg, or 400 mg of anhydrous theophylline per capsule, in an extended-release formulation which allows a 24-hour dosing interval for appropriate patients. Inactive ingredients are edible ink (which contains synthetic black iron oxide, FD&C Blue No. 1, FD&C Blue No. 2, FD&C Yellow No. 6, D&C Yellow No. 10, FD&C Red No. 40), ethylcellulose, gelatin, pharmaceutical glaze, colloidal silicon dioxide, starch, sucrose, talc, titanium dioxide, and coloring agents: 100 mg-includes FD&C Yellow No. 6; 200 mg-FD&C Red No. 3 and D&C Yellow No. 10; 300 mg-FD&C Blue No. 1 and FD&C Red No. 40; 400 mg-FD&C Red No. 40 and D&C Red No. 28.

Theo-24 (theophylline anhydrous capsule) ® Extended-release capsules meet Drug Release Test 6 as published in the current USP monograph for Theophylline Extended-release Capsules.

What are the possible side effects of theophylline (Elixophyllin, Theo-24)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using theophylline and call your doctor at once if you have a serious side effect such as:

  • severe or continued vomiting;
  • rapid or uneven heartbeats;
  • seizure (convulsions);
  • confusion, tremors or shaking;
  • nausea and vomiting, severe headache, rapid heart rate;
  • low potassium (confusion, uneven heart rate, extreme thirst, increased urination, leg...

Read All Potential Side Effects and See Pictures of Theo-24 »

Last reviewed on RxList: 4/8/2009
This monograph has been modified to include the generic and brand name in many instances.

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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