Erythromycin Desloratadine

There was no clinically relevant interaction between desloratadine and erythromycin (9). 

Banfield C, Hunt T, Reyderman L, Statkevich P, Padhi D, Affrime M. Lack of clinically relevant interaction between desloratadine and erythromycin. Clin Pharmacokinet 2002 41(Suppl l) 29-35. 

Combined desloratadine 7.5 mg/day plus erythromycin 500 mg qds in 24 healthy volunteers was well tolerated and had no chnically important electrocardiographic effects (61). Although co-administration of erythromycin slightly increased plasma concentrations of desloratadine, this change did not correlate with prolongation of the QT interval, and there was no toxicity. 

There is a case of torsade de pointes possibly due to spiramycin with the sedating antihistamine mequitazine. The situation with erythromycin and loratadine is unclear as one study found that the combination caused a very slight increase in QT interval. Both azithromycin and erythromycin raise fexofenadine levels, but this had no effect on the QT interval, or on adverse events. Azelastine, cetirizine, desloratadine, and intranasal levocabastine seem to be free of clinically relevant interactions with macrolides. 

Fexofenadine levels are raised by both azithromycin and erythromycin but because this does not result in adverse cardiac effects concurrent use is considered safe. Azelastine, cetirizine (and therefore probably its isomer levocetirizine) desloratadine and levocabastine seem to be free from clinically significant pharmacokinetic interactions, and have no cardiac effects, and so may therefore provide suitable alternatives if a non-sedating antihistamine is needed in a patient taking macrolides. 

Desloratadine 7.5 mg daily Erythromycin 500 mg three times daily 10 24 healthy subjects 20% 10% No change 5... 

---