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Tadalafil for erectile dysfunction: 2005 update

Clinical bottom line

Tadalafil has been studied in a large number of men. At the fixed doses of 10 or 20 mg, it has considerable efficacy, with a number needed to treat below 2, and 75% of men have improved erections. Headache (13%), dyspepsia (10%), flushing (5%), and rhinitis (3%) were the most common individual adverse events.


Reference

RA Moore et al. Indirect comparison of interventions using published randomised trials: Systematic review of PDE-5 inhibitors for erectile dysfunction. BMC Urology 2005 2005, 5:18.


Systematic review

Randomised trials were sought of three PDE-5 inhibitors (sildenafil, tadalafil, vardenafil), with placebo or active comparator, in men with erectile dysfunction of any causation, with drugs used at home. Previous systematic reviews were used to source trials or trial data, supplemented by electronic searches of PubMed (to June 2005, and supplemented by searches to November 2005 for this update) and the Cochrane Library (issue 1, 2005) using drug names and randomis(z)ed trial.

Information extracted was of efficacy, using a number of different efficacy outcomes, discontinuations, and specific adverse events. Almost all information was available for the 20 mg dose, with a small amount for the 10 mg dose; information was combined for 10 and 20 mg.

Results

None of the trials used an active comparator, and most scored highly on reporting quality. All were randomised and double blind for inclusion in the review. Most of the studies used an enriched enrolment in which previous unsuccessful treatment with a PDE-5 inhibitor was an exclusion criterion.

Most studies were in men with erectile dysfunction of mixed aetiology, diabetes, or following prostatectomy. Studies were conducted mainly in Europe and North America.

Erectile function

With tadalafil 10/20 mg, the erectile function domain score rose to 22 (compared with 15 for placebo), an average 8-point change. Successful attempts at intercourse occurred 62% of the time, compared with 26% with placebo.

On average, in 1,694 men in 8 trials, 75% of men reported improved erections, compared with 23% with placebo (Figure 1). The number needed to treat for one man to have improved erections compared with placebo was 1.9 (95% confidence interval 1.8 to 2.1; Table 1).

Figure 1: Improved erections in comparisons of tadalafil and placebo

Table 1: Efficacy and adverse event outcomes in comparisons of tadalafil and placebo

Number of
Percent with
Outcome
Trials
Patients
Tadalafil
Placebo
Relative benefit or risk
(95% CI)
NNT/NNTp/NNH
(95% CI)
Efficacy
Improved erections
8
1694
75
23
3.2 (2.8 to 3.8)
1.9 (1.8 to 2.1)
Discontinuation
All-cause
5
1334
13
19
0.7 (0.5 to 0.9)
15 (8.8 to 46)
Lack of efficacy
6
1432
3.3
7.5
0.5 (0.3 to 0.7)
24 (14 to 69)
Adverse event
7
1655
3.4
1.5
2.3 (1.1 to 5.1)
52 (29 to 260)
Adverse events
All cause
3
590
47
25
1.8 (1.4 to 2.3)
4.6 (3.4 to 7.2)
Serious
7
1651
1.2
1.1
1.0 (0.4 to 2.8)
not calculated
Headache
7
1810
13
3.4
3.5 (2.2 to 5.4)
11 (8.5 to 14)
Dyspepsia
6
1396
10
0.2
12 (4.3 to 35)
11 (8.8 to 14)
Flushing
6
1525
4.8
0.2
7.2 (2.5 to 20)
24 (18 to 38)
Rhinitis
2
711
3.1
0.5
4.5 (0.8 to 24)
not calculated
NNT is given in standard font, NNTp in bold, and NNH inbold italic. No NNT/NNTp/NNH was calculated unless there was a statistically significant difference

 

Adverse events

All-cause discontinuation and lack of efficacy discontinuation were less frequent with tadalafil than placebo, but adverse event discontinuation more frequent. About 2% more men discontinued because of adverse events with tadalafil than with placebo (Table 1).

About half of men had some adverse event, but serious adverse events were no more common with tadalafil than with placebo in these trials. Headache (13%), dyspepsia (10%), flushing (5%), and rhinitis (3%) were the most common individual adverse events.

Comment

Tadalafil has been studied in a large number of men. At the fixed doses of 10 or 20 mg, it has considerable efficacy, with a number needed to treat below 2.