By: EPG Patient Direct


The TADTEST study examined whether adding testosterone replacement therapy could improve sexual function in men with erectile dysfunction(ED) who had not responded to the PDE5 inhibitor tadalafil, a prescription drug used to treat ED. It also investigated the effect that testosterone levels had on response to a PDE5 inhibitor to see if there was a threshold value for testosterone therapy to improve the effectiveness of PDE5 inhibitor therapy.

The 173 men (age 45–80 years) in the study had not responded to 4 weeks of treatment with the PDE5 inhibitor tadalafil 10 mg once a day. For the next 12 weeks men continued treatment with the PDE5 inhibitor with the addition of either testosterone gel once a day or a dummy drug (placebo gel). The dose of the testosterone gel could be doubled if sexual function did not improve sufficiently.

Key Findings

  • Improvements in erectile function and the ability to have successful intercourse were significantly better for men with testosterone levels ≤300 ng/dL or ≤10.4 nmol/L (a widely accepted definition of hypogonadism or low testosterone) at the start of the study when using the testosterone gel in addition to the PDE5 inhibitor than for men in the PDE5 inhibitor plus placebo gel group (see Figure)
  • Men with lower levels of testosterone at the start of the study responded less well to PDE5 inhibitor therapy alone.

Source: Hypogonadal men nonresponders to the PDE5 inhibitor tadalafil benefit from normalization of testosterone levels with a 1% hydroalcoholic testosterone gel in the treatment of erectile dysfunction (TADTEST study). Buvat J, Montorsi F, Maggi M, et al. J Sex Med 2011;8(1):284-293.

Background information
Around a third of men with ED receiving PDE5 inhibitor therapy do not benefit from treatment.

  • There is evidence that the effectiveness of these ED drugs depends in part on testosterone levels
  • Having testosterone deficiency seems to predict a poor response to drugs for ED
  • Other studies have also shown that adding testosterone therapy to ED therapy may help to improve erectile function in men with low testosterone
  • However, these studies did not compare results for men who did receive testosterone therapy or a dummy (placebo) treatment.

This comparative study shows that men with low testosterone levels may benefit from the addition of testosterone replacement therapy to optimal therapy for ED.

Testsoterone therapy improved sexual function

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