Terbinafine Theophylline

ITRACONAZOLE, KETOCONAZOLE, POSACONAZOLE BRONCHODILATORS -THEOPHYLLINE t theophylline levels, with risk of toxicity, with itraconazole. Unpredictable effect on theophylline levels with ketoconazole Theophylline is primarily metabolized by CYP1A2. Although azoles are best known as inhibitors of CYP3A4, they also inhibit other CYP isoenzymes to varying degrees If concurrent use is necessaiy, monitor theophylline levels at the initiation of itraconazole therapy or on discontinuing therapy. Terbinafine may be a safer alternative... 

Theophylline is largely metabolized by CYP1A2 and terbinafine increases its half-life (69). In a randomized, crossover study in 12 healthy volunteers, terbinafine increased theophylline exposure by 16%, with a 14% reduction in clearance and a 24% increase in half-life (69). These pharmacokinetic changes may predispose individuals to accumulation of theophylline and unwanted toxicity. Caution should be taken in prescribing terbinafine for patients taking long-term theophylline. 

Trepanier EF, Nafziger AN, Amsden GW. Effect of terbinafine on theophylline pharmacokinetics in healthy volunteers. Antimicrob Agents Chemother 1998 42(3) 695-7. 

Preliminary evidence indicates that terbinafine can increase the serum levels of theophylline to some extent, but the clinical importance of this is uncertain. 

---