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Author: Admin | 2025-04-28
Common adverse effects for tadalafil and sildenafil, respectively, were headache (11.2% versus 8.8%), dyspepsia (6% versus 4.2%), nasopharyngitis (4.7% versus 2.8%) and flushing (2.8% versus 4.7%). The findings of this trial only apply to the doses tested. As most trials of sildenafil alone show that most men with ED prefer sildenafil 100mg over 50mg, it may have been more appropriate to have compared tadalafil 20mg to sildenafil 100mg. In a second trial of sildenafil and tadalafil, ED patients who were taking sildenafil were switched to tadalafil and then asked which they preferred, with most preferring tadalafil. The 147 evaluable men in this study had been taking stable fixed doses of sildenafil 25mg, 50mg or 100mg as needed, for at least six weeks and up to 24 weeks. After a three-week pre-study sildenafil dose, there was a nine-week tadalafil initiation/assessment phase, at the end of which, the ED subjects could select either sildenafil or tadalafil for a six-month extension. Most (90%) of the men selected tadalafil, and the proportions preferring tadalafil were similar irrespective of age, severity of ED, aetiology of ED, and sildenafil dose at study entry. The obvious limitation to this study was that it was not blinded, and another limitation was that it did not determine the effect on erectile function. When a blinded trial was undertaken to evaluate patient preference between tadalafil 20mg and sildenafil 50mg-100mg, most ED patients preferred tadalafil. Thus, 73% of 181 ED patients chose to receive tadalafil during the extension period. These studies have the same limitation as the crossover study, namely, that the comparison should have been between tadalafil 20mg and sildenafil 100mg. For instance, in the blinded trial, only 35% of the men had the ability to titrate to sildenafil 100mg. This may have biased the preference towards tadalafil. Sildenafil versus tadalafil There is a major point of difference between sildenafil and tadalafil in that tadalafil is considered to have a much longer duration of action. Tadalafil therefore allows more choice regarding the onset of sexual intercourse. The dosing instructions for sildenafil are that patients take sildenafil one hour before sexual activity, whereas those for tadalafil suggest that sexual activity can be initiated between 30 min and 24 hour after dosing. This seems to be very important, as in comparison trials of sildenafil and tadalafil, most men prefer to take tadalafil. As these trials did not investigate why tadalafil was preferred, it is possible that there may be another, at present unclear, reason why men prefer tadalafil over sildenafil in ED. Given that these agents have similar safety and tolerability profiles, these preference results of tadalafil over sildenafil become important, and tadalafil may displace sildenafil as the drug of choice in the treatment of ED. REFERENCE: Doggrell SA. Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction. Expert Opin Pharmacother, 2005.
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