Washington University Case Conference: Theophylline toxicity.

This case demonstrates the importance of monitoring theophylline concentrations in serum during therapy with this drug. The commonly used body-weight-derived guidelines for therapeutic dose are not adequate and do not preclude the necessity for such monitoring. The ultraviolet spectrophotometric methods available for serum theophylline analysis are generally suitable; however, the more specific liquid-chromatographic techniques have certain advantages in that they require only small amounts of serum (25--50 microliter) and are relatively free of interferences from other commonly used drugs. The enzyme immunoassay procedure also appears well suited for the routine measurement of theophylline. The therapeutic range for serum theophylline is well established (10--20 mg/liter) and theophylline values correlate well with therapeutic response and toxicity. We therefore recommend that theophylline in the serum be monitored regularly and dosages adjusted accordingly.