Comparison of Phosphodiesterase Type 5 (PDE5) Inhibitors

P. J. Wright


Int J Clin Pract. 2006;60(8):967-975. 

In This Article

Summary and Introduction

Following publication of this article, the publisher was alerted to an error. A corrected version of the paper appears below. In the original version of Table 2 the dose for vardenafil appeared incorrectly as 100 mg. In the corrected Table 2, the dose for vardenafil is 20 mg.

Of the current options available to treat erectile dysfunction, oral phosphodiesterase type 5 (PDE5) inhibitors are the recommended first-line treatment. This review compares the three currently licensed PDE5 inhibitors: sildenafil citrate (sildenafil), vardenafil HCl (vardenafil) and tadalafil. All three drugs have similar efficacy and toxicity profiles. Sildenafil and vardenafil have similar molecular structures, but tadalafil is structurally different, which is reflected in its pharmacokinetic profile. With regard to the onset of action, achievement of an erection that leads to successful intercourse has been reported for 35% of patients treated with sildenafil within 14 min, 21% of patients treated with vardenafil within 10 min and 16% of patients treated with tadalafil within 16 min. Sildenafil and vardenafil both have half-lives of approximately 4 h but the half-life of tadalafil is 17.5 h. Another difference between the PDE5 inhibitors is that food, especially fatty food, affects the pharmacokinetic profiles of sildenafil and vardenafil, but not that of tadalafil. These pharmacokinetic differences among the PDE5 inhibitors may underlie patient preference, an important and emerging aspect of ED therapy.

The taboo surrounding the discussion of erectile function, although still present, has lessened. This change, to some extent, was due to the introduction of sildenafil in 1998, which revolutionised the treatment of erectile dysfunction (ED). Since then, the awareness of ED has increased, as has the recorded incidence of ED.[1,2,3]

The introduction of vardenafil and tadalafil has now expanded the number of available options for the treatment of ED. These drugs share the same mechanism of action as sildenafil and are also known as phosphodiesterase type 5 (PDE5) inhibitors. This expanded range of therapeutic options leads healthcare professionals to consider how these drugs compare in terms of efficacy, safety and convenience. This review aims to address this issue by providing a comparison of the currently available PDE5 inhibitors.


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