Examples
Sildenafil was the prototypical member of the PDE5 inhibitors. Two other agents, with their own advantages/disadvantages, are also available, and several others are in development.
- avanafil
- lodenafil
- mirodenafil
- sildenafil
- tadalafil
- vardenafil
- udenafil
- zaprinast
Note that while these drugs preferentially inhibit PDE5, none of them is truly selective, especially at high doses. Sildenafil also inhibits PDE6 and PDE9, with inhibition of PDE6 in the retina thought to be responsible for the vision changes which can be a side effect of the drug. Similarly tadalafil inhibits both PDE5 and PDE11. However the selectivity of the existing drugs is high enough that inhibition of additional PDE subtypes is not generally a problem in clinical use, and while newer "super-selective" PDE5 inhibitors have been developed for research purposes, it is unlikely any of these will be marketed given the saturation of the erectile dysfunction market at present.
Claimed newer inhibitors are icariin, an active component of Epimedium grandiflorum and possibly 4-Methylpiperazine and Pyrazolo Pyrimidin-7-1, said to be components of the lichen Xanthoparmelia scabrosa.
Read more about this topic: PDE5 Inhibitor
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