Co-administration of a single 5 mg oral dose of linagliptin and multiple 200 mg oral doses of ritonavir, a potent inhibitor of P-glycoprotein and CYP3A4, increased the AUC and Cmax of linagliptin approximately two-fold and three-fold, respectively. The unbound concentrations, which are usually less than 1% at the therapeutic dose of linagliptin, were increased 4-5-fold after co-administration with ritonavir. Simulations of steady-state plasma concentrations of linagliptin with and without ritonavir indicated that the increase in exposure will be not associated with an increased accumulation. These changes in linagliptin pharmacokinetics were not considered to be clinically relevant.
Trajenta Summary of Product Characteristics, Boehringer Ingelheim International, October 2012.

 

Coadministration of linagliptin (5 mg single dose) and ritonavir (200 mg twice daily) increased linagliptin AUC by ~2-fold and increased Cmax by ~3-fold.
Tradjenta US Prescribing Information, Boehringer Ingelheim International, September 2012.