Tadalafil (Cialis) is the third oral medicine approved by the U.S. FDA for the treatment of erectile dysfunction. Like sildenafil (Viagra) and vardenafil (Levitra), tadalafil inhibits PDE5.
How effective is tadalafil?
The safety and efficacy of tadalafil in the treatment of erectile dysfunction was evaluated in 22 clinical trials involving more than 4,000 men. Seven of these trials were randomized, prospective, placebo-controlled studies of 12 weeks’ duration. Two of these studies (involving 402 men) were conducted in the United States, and the other five studies (involving 1,112 men) were conducted outside the United States. Two of these trials were conducted in special populations with erectile dysfunction; one in men with diabetes mellitus, another in men who developed erectile dysfunction after nerve-sparing prostate cancer surgery.
Effectiveness of tadalafil in these studies was assessed using a sexual function questionnaire. Study participants also were asked if they were able to achieve vaginal penetration and to maintain erections long enough for successful intercourse.
In all seven trials, tadalafil was significantly better than placebo in improving men’s ability to achieve and maintain erections. Improvements in erectile function was observed in some patients at 30 minutes after taking a dose; and improvements can last for up to 36 hours after taking Cialis when compared to placebo.
How should tadalafil be administered?
The recommended starting dose of tadalafil for most patients is 10 mg taken orally approximately one hour before sexual activity. The dose may be adjusted higher to 20 mg to 40 mg or lower to 5 mg depending on efficacy and reliability. The maximum recommended dosing frequency is once per day, although for many patients tadalafil can be taken less frequently since the improvement in erectile function may last 36 hours. Tadalafil may be taken with or without food. Tadalafil is also available in 2.5 mg. or 5 mg. dosages for daily use