Tools for Practice

#245 Taking a hard look at the evidence: Phosphodiesterase-5-inhibitors in erectile dysfunction

What is the efficacy and safety of phosphodiesterase-5-inhibitors (PDE5 inhibitors) for erectile dysfunction?

PDE5 inhibitors increase the proportion of successful sexual intercourse attempts to ~65% versus ~30% for placebo. For every 3 men given a PDE5 inhibitor compared to placebo, an additional 1 will have “improved erections”.  

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All results statistically significant unless indicated. 
  • Systematic review, 130 randomized controlled trials (RCTs) of most PDE5 inhibitors (sildenafil, vardenafil, tadalafil, mirodenafiludenafil), over 30,000 patients with erectile dysfunction of any cause.1,2 After ~12 weeks: 
    • Proportion of successful sexual intercourse attempts (erection sufficiently hard and long lasting for satisfactory intercourse): 
      • ~65% versus ~30% (placebo). 
    • Proportion of patients with self-reported “improved erections” using PDE5 inhibitors: 
      • ~78% versus 31% (placebo), Number Needed to Treat (NNT)=3. 
  • Systematic review, 118 RCTs, n=31,195, all PDE5 inhibitors:3 
    • Proportion of patients with “improved erections”: ~79% versus ~29% (placebo); NNT=2. 
  • Systematic review, 8 RCTs, n=1759, men with diabetes:4 
    • Proportion of patients with “improved erections”: ~58% for PDE5 inhibitors versus ~15% placebo; NNT=3. 
  • Adverse effects: 
    • Any adverse event:1 ~44% versus ~24% (placebo), mainly headache, flushing, dyspepsia. 
    • Withdrawal due to adverse effects: Sildenafil5, vardenafil2 not different from placebo, tadalafil 1.6-3.2% versus 1.3% placebo5, number needed to harm=52-333. 
  • Limitations: 
    • Majority of RCTs unclear randomization concealment/blinding methods.1,6,7 
    • Many RCTs industry supported.1,2 
    • Other systematic reviews inadequately reported symptom scores or used scales with limited clinical meaning.5,6,8,9 
  • Prevalence of erectile dysfunction is ~30-50% in men aged 40–70; increases with age and comorbidities.1,5  
  • Contraindicated with concurrent nitrate use.2 
  • All PDE5 inhibitors: $50-$65 for 4 tabs (or $13-$16/tablet independent of dose) and not generally covered by public drug plans.10  
    • Cost may be reduced by pill splitting. 
  • On-demand versus daily dosing of tadalafil: no clinically meaningful difference in change of erectile function and no difference in adverse event discontinuation rates.6,7 

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  • Adrienne J Lindblad BSP ACPR PharmD
  • Caitlin R Finley BHSc MSc
  • Lindsey Ziegler BSc BPharm

Tsertsvadze MD, Fink H, Yazdi F, et al. Ann Intern Med. 2009; 151(9):650-661.

Tsertsvadze A, Yazdi F, Fink H, et al. Evidence Report/Technology Assessment No. 171 (prepared by the University of Ottawa Evidence-based Practice Centre (OU-EPC) under Contract No. 290-02-0021). AHRQ publication No. 08(09)-E016, Rockville, MD: Agency for Healthcare Research and Quality. May 2009.  Available at: Accessed 31 May 2019.

Yuan J, Zhang R, Yang Z, et al. Eur Urol. 2013; 63:902-912.

Vardi M and Nini A. Cochrane Database System Rev. 2007; 1:CD002187.

Khera M and Goldstein I. BMJ Clinical Evidence. 2011; 06:1803.

Peng Z, Yang L, Dong, Q et al. Urol Int. 2017; 99:343-352.

Bansal UK, Jones C, Fuller TW et al. Urology. 2018; 112:6-11.

Fink H, MacDonald R, Indulis R, et al. Arch Intern Med. 2002; 162:1349-1360.

Berner MM, Kriston L and Harms A. Int J Impot Res. 2006; 18:229-235.

PEER. Price Comparison of commonly prescribed Pharmaceuticals in Alberta 2019. Available at: Accessed 27 June 2019.