Decreased elimination of theophylline after influenza vaccination.

The elimination of theophylline is decreased after vaccination against influenza. In three 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 four 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 three 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.