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Tadalafil for erectile dysfunction

 

Clinical bottom line

Both 10 mg and 20 mg of tadalafil were significantly better than placebo in producing erections hard enough for penetration, hard enough for penetration and of long enough duration for successful intercourse, and provided improved erections. Numbers needed to treat for improved erections were 2.6 for tadalafil 10 mg and 2.0 for tadalafil 20 mg.


Reference

CC Carson et al. The efficacy and safety of tadalafil: an update. BJU International 2004 93: 1276-1281.


Background

Though a number of systematic reviews of sildenafil have been published in the years before 2004, systematic reviews and meta-analyses of the newer oral erectile dysfunction drugs in the same class (phosphodiesterase type 5 inhibitor) have not been until 2004. This at least opens the possibility of comparing and contrasting different treatments based on similar trials with similar outcomes.

Systematic review

The review calls itself an integrated review. There is no search strategy, and the assumption is that the data comes from studies conducted by Eli Lilly, as one of the authors is an employee. No non-company studies are therefore likely. It is not certain whether the data come from clinical trial reports, or databases.

Patients in the trials were required to make at least four attempts at intercourse during a four-week treatment-free period. They were then randomised to 12 weeks of treatment with placebo, or tadalafil 10 or 20 mg. Treatment was taken as needed before sexual intercourse, without restrictions on food or timing of sexual activity.

Men had to be 18 years old or older, with a minimum three-month history of mild to severe erectile dysfunction of organic, psychogenic, or mixed causes. They had to have a steady female partner. Most studies excluded non-responders to previous sildenafil treatment.

Results

There were 2,102 men in the trials, with an average age of 56 years. And 22% over age 65 years. Most had a history of erectile dysfunction of over a year. Medical history of hypertension (29%), diabetes (20%), hyperlipidaemia (16%) coronary artery disease (5% and depression (4%) were common. Severity of erectile dysfunction was mild in 36%, moderate in 27% and severe in 33%.

Completion rates in trials was high (89%), with adverse event discontinuation (3.2%) or lack of efficacy discontinuation (1.6%) uncommon. Analyses were by intention to treat, using a definition of all patients measured at baseline with at least one later measurement, which means that men had to complete four weeks.

Efficacy

Both 10 mg and 20 mg were significantly better than placebo in producing erections hard enough for penetration, hard enough for penetration and of long enough duration for successful intercourse, and provided improved erections (Table 1). Numbers needed to treat for improved erections were 2.6 for tadalafil 10 mg and 2.0 for tadalafil 20 mg.

Table 1: Results for tadalafil in erectile dysfunction

 
Percent with
 
Tadalafil 10 mg
Placebo
NNT
(95%CI)
Q2: Effective penetration
73
50
4.4 (3.4 to 6.0)
Q3: Successful intercourse
58
31
3.7 (3.0 to 4.9)
Improved erections
71
33
2.6 (2.3 to 3.2)
 
Tadalafil 20 mg
Placebo
NNT
(95%CI)
Q2: Effective penetration
80
50
3.3 (2.9 to 3.9)
Q3: Successful intercourse
68
31
2.7 (2.4 to 3.1)
Improved erections
84
33
2.0 (1.8 to 2.1)
Note that the NNTs have been calculated from all patients, not with matched placebos, and are therefore approximate

 

Efficacy was achieved at all levels of erectile dysfunction severity, for erectile dysfunction of organic, psychogenic, or mixed origin, and for men younger and older than 65 years. Similar levels of efficacy were recorded for men attempting intercourse within 30-60 minutes after dose out to those attempting intercourse 24-36 hours after dose.

Harm

Few patients discontinued because of adverse events, rising from 1.3% with placebo to 3.2% with tadalafil 20 mg. Men with at least one adverse event over the course of treatment were common, 39% for placebo, 58% for 10 mg and 51% for 20 mg. The most common adverse events were headache (15% with tadalafil 20 mg), dyspepsia (8%), and back pain (5%).

Comment

Tadalafil is effective in erectile dysfunction. It appears to be about as effective as sildenafil, the first phosphodiesterase inhibitor used for erectile dysfunction. There are limitations about the review, notably about what proportion of the trial database has been used, and whether there are other trials available not performed by the manufacturer. No trial used sildenafil as a comparator, nor any other comparator.