Selective phosphodiesterase type 5 inhibition using tadalafil for the treatment of erectile dysfunction

Erectile dysfunction (ED) pharmacotherapy has undergone dramatic advances over the past decade, since the introduction of phosphodiesterase type 5 inhibitors (PDE5). The availability of an oral agent, sildenafil, able to restore erectile function in the majority of men with an organic basis to their dysfunction, transformed the management. The numbers of men seeking medical attention for ED, along with the increased comfort of physicians treating it, has resulted in enhanced management of this condition. In spite of these advances, there exist a significant number of men who remain unsuccessfully treated with sildenafil. Development of new PDE5 inhibitors, with the promise of enhanced selectivity, longer duration of action, increased potency and greater ease of use are currently in the final stages of regulatory review in many countries. Tadalafil is the first such agent to gain preliminary EU approval and is reviewed in detail in this report. Focusing on its phase II/III trial results, tadalafil appears to have an enhanced period of responsiveness extending out to 36 hours in 60% of men using the 20 mg dose. Efficacy across a large population of men with ED of various causes (n = 1112) is in accordance with the other PDE5 inhibitors at 81%. Side effects are generally mild-to-moderate with study drop-out rate at 1.7% in the active arm compared to 1.1% among those receiving placebo. In summary, this agent will likely play an important role in the management of ED across a broad spectrum of aetiologies, once past the ongoing regulatory review process.