Drug Interactions with Theophylline

Drug Interactions with Theophylline

Synergism and Additive Effects

  • Synergism between ß2-adrenergic agonists and theophylline demonstrated in vitro.

  • Clinical effect of this combination is at best additive.

Factors Affecting Theophylline Metabolism

  1. Inhibitors of CYP1A2

    • Drugs that inhibit CYP1A2 can precipitate theophylline toxicity:

      • Erythromycin (and other macrolides)

      • Fluoroquinolones (e.g., ciprofloxacin)

      • Interferon

      • Cimetidine

  2. Inducers of CYP450

    • Theophylline metabolism is induced by hepatic CYP450-inducing agents:

      • Rifampicin

Conclusion

  • Awareness of drug interactions is crucial for managing theophylline therapy and preventing toxicity.