Tadalafil is at least 9000 times more selective for PDE5 than most of the other families of PDEs, with the exception of PDE11. PDE11 is found in the testes and prostate; however, despite partial inhibition of PDE11 by tadalafil at therapeutic doses, clinical significance of this observation has yet to be fully understood. A study [...]

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Although the effectiveness of PDE5 inhibitors on such intermediate objective outcomes as penile rigidity through penile plethysmography with the RigiScan device (Dacomed Corporation, Minneapolis, MN, USA) has been studied, measuring the therapeutic effectiveness of tadalafil (Cialis Professional) is more accurately defined through an integration of the patient’s reported treatment response and tolerability with the reported [...]

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The three available PDE5 inhibitors share a similar mechanism of action, but they have structural, pharmacologic, and clinical differences. The molecular structure of tadalafil is available in Figure 1. Tadalafil’s molecular structure is different than the similar structures of generic sildenafil and generic vardenafil. All three have a heterocyclic nitrogen-containing doublering system, with a central [...]

read more from " Tadalafil pharmacology "