Salivary and Urine Theophylline Levels in Management of Childhood Asthma

It is not possible to predict the plasma theophylline levels that can be achieved using slow-release aminophylline based on body weight or surface area. Improvement in FEV₁ is directly related to increasing serum theophylline level, justifying the need for measuring levels in order to optimize therapy. As repeated venesection in children is unpleasant we have studied a simple method using saliva. Simultaneous blood and salivary theophylline levels correlated sufficiently well for salivary levels to be used for monitoring purposes. Urine levels did not correlate as well, but could be used for checking compliance.