Low dose tadalafil -- Effective treatment for depression with Erectile Dysfunction

Korea: Daily low dose tadalafil, phosphodiesterase (PDE) 5 inhibitor, may have a potential role in the treatment of depression in patients with erectile dysfunction (ED), according to a recent study published in the journal Translational Andrology and Urology.

Erectile dysfunction and depression are closely related to each other -- depression and antidepressants can cause ED, and also having ED increases the risk for depression. Therefore, there is a need for a drug than can simultaneously treat both ED and depression.

PDE 5 inhibitors that regulate certain signaling pathways by elevating cyclic guanosine monophosphate (cGMP) levels have been widely used for ED treatment. They increase the levels of cGMP by blocking its breakdown at its catalytic site. Increased cGMP facilitates changes in neuronal activities in the brain. Though many clinical studies have suggested a role of other PDE5 inhibitors, like sildenafil and vardenafil, as possible antidepressant medications, there have been only a few animal studies exploring tadalafil but no clinical studies.

Furthermore, studies have found an association between brain-derived neurotrophic factor (BDNF) and depressive disorders. cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) was found among the transcription factors regulating BDNF expression.

Jun Sung Koh, Catholic University of Korea, Republic of Korea, and colleagues investigated the effect of a daily low dose of a PDE type 5 inhibitor (tadalafil, 5 mg) on depression and levels of brain-derived neurotrophic factor (BDNF) in patients with ED.

The researchers analyzed 10 male patients with at least a 3-month history of ED [International Index of Erectile Function (IIEF)-5 score ≤21] and depression [the Korean version of the Patient Health Questionnaire (PHQ)-9 score ≥5]. The patients were prescribed a low dose of a PDE5 inhibitor (tadalafil 5 mg) once daily for 8 weeks.

The survey questionnaires were performed using the PHQ-15 and the PHQ-9 before and after administration of 8 weeks of tadalafil. Blood samples used for measuring serum BDNF levels were taken and measured at baseline and after 8 weeks of treatment.

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Key findings of the study include:

• The mean changes in the PHQ-9 and PHQ-15 scores were 3.60±3.27 and 2.00±2.98, respectively.


• Analyses of the mean changes in the PHQ-9 scores revealed that the depressive symptoms of the subjects were significantly improved after the administration of eight weeks of tadalafil.


• There was also a statistically significant increase in the PHQ-15 scores.


• Serum levels of BDNF were higher after tadalafil treatment compared to before treatment; however, this difference was not statistically significant.

"A randomized placebo-controlled study using a larger sample size is required to elucidate the mechanism underlying the improvement of depressive symptoms in ED patients seen with tadalafil treatment," concluded the authors.