The Art of Andrology: Optimizing Treatment for Erectile Dysfunction
Sildenafil: Shaping the management of ED
Originally developed as an anti-anginal drug, sildenafil citrate has evolved to an on-demand oral treatment for ED, in which it has demonstrated highly potent and selective inhibition of the enzyme phosphodiesterase type 5 (PDE5).4 Ever since the scientific publication of its use for the treatment of ED in human subjects in the late 1990s,5,6 sildenafil has revolutionized the management of ED. Not only did sildenafil change how physicians perceive sexual health in general,7 it also led to an explosion of research on ED, including the development and validation of several instruments to evaluate ED and its treatment efficacy.8–11 A few other PDE5 inhibitors are now available and Table 1 summarizes the pharmacokinetic profile of these drugs.
Implications of a Grade 4 erection
The Erection Hardness Score (EHS) is a simple, reliable and patient-reported outcome for scoring erection hardness, because it displays clear differentiation between normal and impaired erectile function as defined by the International Index of Erectile Function (IIEF) questionnaire.11
Grade 4 erection, according to the EHS, implies that the penis is completely hard and fully rigid; it is essentially the desired outcome of ED management. A Grade 4 erection is important because:
- It is directly correlated to successful sexual intercourse (SSI): the percentage of SSI increases from almost 60% at EHS 3 to 93.1% at EHS 4.16
- A shift from Grade 3 erection (hard enough for penetration but not completely hard) to Grade 4 is significantly associated with improvements in psychosocial measures such as self-esteem, confidence, and relationship and intercourse satisfaction.17
- Driving men to greater erectile rigidity appears to translate to lower dropout rates, ie, higher treatment adherence.18
According to the Princeton Consensus Panel, patients who are not taking nitrates of any form, with low cardiac risk, and have enough exercise reserve to resume sexual activity, can receive treatment for ED.19 “Other factors such as sexual dynamics, frequency and predictability of sexual activity, and integratability of treatment with sexual activity, may decide which PDE5 inhibitor is suitable for a particular patient,” said Professor Mulhall.
Speaking from his own clinical experience, Professor Mulhall noted that sildenafil 100 mg is a good starting dose, and this may be down-titrated to manage any possible side effects or if treatment response is excellent. In the study by Buvat et al,20 patients with ED who were titrated to sildenafil 100 mg had significantly greater improvement in the erectile function domain of the IIEF compared with those on sildenafil 50 mg (Figure 1). The improvement in erectile function was also correlated with significant improvement in the sexual desire, intercourse satisfaction and overall satisfaction domains of the IIEF.
Pooled safety analysis from 67 double-blind placebo-controlled trials involving more than 14,000 men confirms the good tolerability and safety profile of sildenafil 50 mg and 100 mg. Common adverse events with sildenafil are those related to the pharmacology of PDE5 inhibition, such as headache, vasodilation and facial flushing. The rates of these adverse events are higher during the first 4–6 weeks of treatment but decrease markedly thereafter, reaching similar rates as placebo-treated patients (Figure 2).21 As for cardiovascular safety, pooled analysis from more than 120 trials of sildenafil found that the rates of myocardial infarction and cardiovascular death were low and comparable with placebo.22
Sildenafil is the first PDE5 inhibitor approved and has shaped the modern management of ED. The use of sildenafil in ED is backed by robust efficacy data; safety analyses revealed that it is well tolerated and does not increase cardiovascular events compared with placebo. Last but not least, optimizing patients’ response to ED treatment requires careful instruction on use of the drug and regular follow-up.
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- Potts A, et al. Sociol Health Illn 2006;28(3):306–329.
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- Buvat J, et al. BJU Int 2008;102(11):1645–1650.
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- SexHealthMatters.org. Treating Erectile Dysfunction. Available at: http://www.sexhealthmatters.org/erectile-dysfunction/treatingerectile-dysfunction. Accessed 8 Oct 2015.