Prodipine (hydrochloride), a diphenyl-phosphonate derivative selected from a group of slow-binding irreversible inhibitors of this enzyme. The IC ₅₀ values of Prodipine for purified and plasma DPP IV from the rabbit are 4.5 μM and 30 μM, respectively.

Male rabbits weighing 3-4 kg receive a single intravenous injection with 10 mg Prodipine (hydrochloride) or saline. After 1 hr, plasma DPP IV activity has decreased to less than 20% of the preinjection value and remains unchanged during a 24 hr observation period. A profound and long-lasting inhibition of plasma DPP IV activity is observed in the treated animals (1, 5 or 10 mg). It takes 5 to 8 days to reach half of the pretreatment DPP IV activity and generally more than 20 days for a complete recovery.

IC50: 4.5 μM (purified DPP IV), 30 μM (plasma DPP IV)