NEW YORK (Reuters Health) May 18 - By relaxing the esophageal wall and decreasing hypersensitivity, theophylline may reduce non-cardiac, non-reflux esophageal chest pain, according to a research team at the University of Iowa in Iowa City.
As Dr. Satish S. C. Rao and colleagues note in the American Journal of Gastroenterology for May, adenosine is believed to be involved in visceral chest pain. They theorized that theophylline, an adenosine receptor antagonist, could reduce the pain.
To investigate, they recruited 21 patients with functional chest pain for a study involving esophageal balloon distention with impedance planimetry. The balloon was passed using a catheter into the lower part of the esophagus. Pressure in the balloon was increased in steps of 5 cm H2O up to a maximum of 65 cm H2O.
Sixteen subjects were deemed to have esophageal hypersensitivity, defined as 55 cm H2O pressure or less required to reproduce their typical chest pain. These subjects were randomly assigned to IV theophylline or placebo IV infusion.
"Theophylline significantly improved distension-induced esophageal chest pain," the investigators report. The threshold for chest pain increased significantly in six of eight patients given theophylline. In fact, five in the theophylline group felt no pain even at the maximum permissible distension pressure.
"The esophageal wall relaxed and became more deformable ... after theophylline infusion," Dr. Rao's team reports.
To test oral theophylline, patients with esophageal hypersensitivity participated in a cross-over study comparing twice daily doses of placebo or theophylline 200 mg. Treatment periods lasted for 4 weeks, with a 1-week washout period in between.
During the trial, the 19 patients kept diaries to record number, severity, and duration of chest pain. Compared with placebo, oral theophylline use was associated with fewer painful days (median 5 versus 10), number of chest pain episodes (8 versus 16), severity assessed on a scale of 0 to 3 (2 versus 3), and duration of episodes (6.5 versus 8.5 minutes).
Esophageal chest pain can be a frustrating problem, Dr. Rao and associates comment. "If a cardiac, pulmonary, musculoskeletal or esophageal source such as acid reflux disease can be excluded, our findings suggest that a trial of theophylline may be effective in relieving chest pain, " they advise.
But they caution that theophylline can potentiate gastroesophageal reflux, and patients should be carefully followed up.
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