| What is Theophylline ER? Theophylline ER (Extended-release) is a bronchodilator used to open air passages in the lungs. It relaxes muscles in the lungs and chest. Theophylline is used in the treatment of heart failure, asthma, bronchitis, and pulmonary edema. Theophylline ER may also be used for purposes other than those listed here. Theophylline ER is sold per tablet and requires a prescription from your veterinarian. |