Decreased elimination of theophylline after influenza vaccination

The elimination of theophylline is decreased after vaccination against influenza. In 3 patients receiving 200 mg of oxtriphylline (equivalent to 128 mg of theophylline) every 6 hours by mouth the serum theophylline levels rose after vaccination, and in 4 healthy volunteers given the same dose of oxtriphylline 24 hours after vaccination the half-life of theophylline increased by an average of 122%. Two of the 3 patients showed signs of a toxic reaction to the drug. These results suggest that the elimination of theophylline is impaired to a clinically important degree after influenza vaccination and that the resulting levels of the drug can be toxic even when conventional therapeutic doses of theophylline are given.