Comparative Randomized Crossover Clinical Study for the Evaluation of Erectile Dysfunction Medications Via Novel Pentagon System

Curr Drug Saf. 2018;13(1):12-20. doi: 10.2174/1574886313666180122163322.


Introduction: Due to the chaos in the legislation in the Middle East, male enhancement nutraceuticals may be sold without any registration or evaluation. These products need to be evaluated with respect to safety and efficacy. Furthermore, cultural and social considerations in the Middle East prevent the use of international evaluations schemes for erectile dysfunction.

Aim: Evaluating the safety and efficacy parameters of generic and nutraceutical products for erectile dysfunction in the Middle East through a custom-designed, representable and simple system tailored to the regional culture.

Methods: 74 healthy male volunteers were enrolled into a comparative, simple randomized, single dose, double blind, and crossover clinical study incorporated with a tailored-designed questionnaire. Safety assessment included laboratory analysis for liver functions and measuring blood pressure.

Main outcome measures: Subjective data regarding safety and efficacy were assessed from the validated questionnaire. Blood pressure was measured. Blood samples were collected to assess the drug/adulterants concentration and liver and kidney functions.

Results: All tested nutraceuticals showed undeclared Sildenafil citrate in patients. Questionnaire results showed high inter-patient variability with respect to efficacy and comparable safety profile compared to Viagra®.

Conclusion: The validated tailored-designed questionnaire effectively assessed the efficacy and safety of male enhancement products. The male enhancement nutraceuticals, sold in Egypt, claimed to be 100% natural are adulterated and of questionable safety profile.

Keywords: Phosphodiestrase inhibitors; adulteration; clinical study; nutraceuticals; pentagon; questionnaire; safety and efficacy assessment; sildenafil; tiger king..

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Cross-Over Studies
  • Dietary Supplements / analysis*
  • Double-Blind Method
  • Drug Contamination* / prevention & control
  • Drugs, Generic / analysis*
  • Drugs, Generic / metabolism
  • Drugs, Generic / therapeutic use
  • Egypt / epidemiology
  • Erectile Dysfunction / blood*
  • Erectile Dysfunction / drug therapy
  • Erectile Dysfunction / epidemiology*
  • Humans
  • Male
  • Middle Aged
  • Phosphodiesterase 5 Inhibitors / analysis
  • Phosphodiesterase 5 Inhibitors / blood
  • Phosphodiesterase 5 Inhibitors / therapeutic use
  • Sildenafil Citrate / analysis*
  • Sildenafil Citrate / blood
  • Sildenafil Citrate / therapeutic use
  • Treatment Outcome


  • Drugs, Generic
  • Phosphodiesterase 5 Inhibitors
  • Sildenafil Citrate