The general trend in medical therapy toward once-daily administration has not escaped theophylline preparations. Rapid metabolizers, as are found especially among children and smoking adults, may require a more frequent interval than once-a-day dosing, and greater fluctuations in theophylline levels should be expected. An interaction with food has been seen with once- and twice-daily theophylline preparations. Some products release their contents more rapidly while others do so more slowly in association with a high-fat diet. The food effect is of little concern if the theophylline is taken 1 hour before the meal. The greatest anticipated value of once-daily theophylline medications would be improved patient compliance.