Clinical studies examining T monotherapy for the treatment of ED have yielded varying results. Meta-analysis, including trials in young organic hypogonadal patients, has shown a 57% response rate for T therapy in patients with ED, ranging from 64% for primary hypogonadism to 44% for secondary hypogonadism . Morales et al. showed that T therapy is an effective treatment for hypogonadal impotence, with improvement in sexual attitudes and performance in 61% of patients . In another study, T monotherapy has been observed to improve erectile function in only 36% of the hypogonadal patients consulting for ED  (see also pp. 203-2).
T therapy may have more significant effects on libido than on erectile function . In one study, normalization of serum T levels in hypogonadal men with ED resulted in only short-term improvement (one month) in erectile function and sexual satisfaction, while improvement of sexual desire was statistically significant for the six months of the study, making the use of T therapy alone questionable in this population . However, T monotherapy did improve sexual performance, desire, and motivation in men with hypogonadism, in clinical trials with transdermal T-gel formulation. Maximal improvement occurred on day 30 and continued for the six-month duration of the study .
There is a lack of data suggesting the efficacy of T therapy in older men who do not meet the clinical definition of hypogonadism. There is no convincing evidence that androgen therapy is either effective or safe for older men, unless a formal diagnosis of hy-pogonadism exists . The US Institute of Medicine (IOM) has recommended additional clinical research focusing on the benefits of T therapy in older men as compared with placebo controls, followed by larger-scale and longer-term trials to assess risks and benefits .
PDE5i are the first line of therapy in men who do not have potentially reversible causes of ED, such as hy-pogonadism . Nonetheless, 23% to 50% of patients do not respond to PDE5i alone [73,172]. Given the role of T in the NO pathway central to proper erectile function, interest in PDE5i-testosterone combination therapy has risen in recent years . As reported on p. 232, the most robust arguments supporting the validity of such a combination come from a randomized, placebo-controlled study of hy-pogonadal men with ED, non-responders to silde-nafil . In addition to improving erectile function,
T therapy improved orgasmic function . In another randomized, placebo-controlled study, short-term transdermal T administration improved the erectile response to sildenafil by increasing arterial inflow to the penis during sexual stimulation . T was also shown to improve arterial flow and subsequent response to tadalafil treatment, with a greater response after 10 weeks, compared to four weeks of pretreatment with T . Lastly, in a recent RCT, sildenafil improved sleep-related erections even in hypogonadal men, but combined therapy with T had greater effects than the sum of the two compounds alone, proving synergy .
Other uncontrolled studies have reported beneficial effects of combination therapy in patients with co-morbid conditions. Administration of intramuscular T and sildenafil was found to be efficacious in renal transplant patients and in patients on renal dialysis . Oral T has been reported to reverse ED associated with type 2 diabetes in patients failing on sildenafil therapy alone . In conclusion, T combination therapy with PDE5i may improve the response to PDEi in patients with ED and hypogonadism.
Was this article helpful?
You are about to discover the "little-known" techniques, tricks and "mind tools" that will show you how to easily "program" your body and mind to produce an instant, rock-hard erection. Learn how to enjoy all of the control, confidence and satisfaction that comes from knowing you can always "rise to the challenge" ... and never have to deal with embarrassment, apologies, shyness or performance anxiety in the bedroom, ever again.