orally active, selective phosphodiesterase type V (PDE V) inhibitor vardenafil (Levitra®), the 14C-labelled version was synthesised. Starting from the cyanation of 2-iodophenol with K14CN, an 8-step synthesis led to two batches with 0.727 g (2.857 GBq) and 2.199 g (5.497 GBq) of [triazinone-14C]vardenafil hydrochlo-ride with different specific radioactivities. The label was located in position 2 of the