Dipeptidyl peptidase-4 inhibition: linking chemical properties to clinical safety.

The new drug class of dipeptidyl peptidase-4 (DPP4) inhibitors has been widely accepted in the daily management of type 2 diabetes since its strategic advantages with regard to body weight, risk of hypoglycaemia, and beta cell survival. We have previously evaluated the theoretical implications of DPP4 inhibition given that the enzyme is involved in regulating biological activity of hormones, neuropeptides, and cytokines. We intend now 1) to provide a critical appraisal of safety and tolerability as they emerged from the available clinical studies, and 2) to establish, if possible, a relation between chemical properties, biological activity, and the observed side effects in vivo.