Largest international trial indicates that testosterone therapy is an effective and well tolerated treatment for male hypogonadism

December 2013

IPASS: Final data from the worldwide largest study of the tolerability and effectiveness of injectable testosterone undecanoate (TU) for the treatment of male hypogonadism involving 1493 patients. M Zitzmann, JU Hanisch, A Mattern, M Maggi. A presentation to the Men’s Health World Congress, 2010.


  • Restoring plasma testosterone levels to normal alleviated the symptoms of testosterone deficiency1
  • The percentage of patients who reported “low” or “very low” levels of sexual desire/libido decreased from 64% at baseline to 10% after four TU injection intervals1
  • At baseline, 67% of patients had moderate, severe or extremely severe erectile dysfunction (ED), this decreased to 19% after TU therapy.1 61% of patients with some degree of ED reported a decrease in severity2
  • TU therapy markedly improved patients ability to concentrate1 and their reported mood1
  • 89% of patients were “satisfied” or “very satisfied” with TU therapy2
  • The mean waist circumference in patients decreased from 100 cm to 96 cm1
  • Intramuscular TU was well tolerated and safe for treatment of male hypogonadism in daily clinical practice, irrespective of ethnic background1: adverse events and adverse drug reactions were recorded for 12% and 6% of patients respectively2. These were mostly mild to moderate in severity2
  • The most commonly reported ADRs were increase in hematocrit, increase in PSA and injection site pain (all <1%)
  • No case of prostate cancer was observed2

What is known

Systematic reviews of randomized, placebo-controlled clinical trials of testosterone in men, including older men (aged 60 years and over) and middle-aged men, with sexual dysfunction and hypogonadism have shown large favourable effects on libido, but moderate effects on satisfaction with erectile function.3,4,5,6,7

Outcomes in clinical trials of the effect of testosterone treatment on mood have varied. However, there has been evidence that testosterone treatment results in improvements in mood, particularly in older men with hypogonadism.8,9

The benefits of testosterone treatment on body composition have consistently been demonstrated in clinical studies of testosterone therapy in hypogonadal men or men with borderline low testosterone levels.3,9,10,11,12

What this study adds

The effectiveness of testosterone, shown previously in randomised placebo-controlled trials, has now been confirmed in a large, unselected patient cohort drawn from clinical practices around the world.

Clinically relevant and beneficial efficacy has been documented especially regarding sexual function and waist circumference.2 Mean body weight in patients also decreased under TU therapy.1 By the end of the trial those men reporting high or very high levels of sexual desire increased to 61% from a 10% baseline.

At baseline 36 per cent of men reported a “very negative” or “negative” mood. This fell to 5 per cent after the fifth injection.


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  • IPASS: Final Data from the Worldwide Largest Study of the Tolerability and Effectiveness of Injectable Testosterone Undecanoate for the Treatment of Male Hypogonadism Involving 1493 Patients. M Zitzmann, JU Hanisch, A Mattern, M Maggi. Undated abstract Return to content
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