Why are xanthine derivatives like theophylline not always preferred for asthma treatment?

Xanthine derivatives like theophylline are not always preferred for asthma treatment primarily because they have a narrow therapeutic range. This means that there is a fine line between the effective dose and the dose that could cause toxicity. Patients taking theophylline require careful monitoring of their blood levels to ensure they remain within this therapeutic range, as levels that are too low may not provide adequate symptom control, while levels that are too high can lead to adverse effects.

In addition to their narrow therapeutic range, theophylline's actions can be influenced by factors such as other medications, diet, and liver function, complicating its use in practice. While theophylline can be a useful bronchodilator, the need for monitoring and the potential risk of toxicity can limit its appeal compared to other asthma treatments that offer a wider margin of safety and more predictable outcomes.