Tadalafil (Table 3). An integrated analysis11 of five randomized, placebo-controlled trials of tadalafil at 2.5, 5, 10, or 20 mg for at least 12 weeks found that the agent at all doses significantly enhanced erectile function in mild to severe ED compared with placebo. Successful intercourse was reported in 61% and 75% of sexual encounters among men treated with tadalafil, 10 and 20 mg respectively, compared with 32% in controls. Eighty-one percent of men taking tadalafil, 20 mg, reported improved erections compared with 35% of those taking placebo.
Tadalafil, 10 and 20 mg, also improved erectile function in men with type 1 or type 2 diabetes.12
All three PDE-5 inhibitors have been shown in clinical trials to be generally safe and well-tolerated. Apart from visual disturbances, all three agents have similar side effects.
- Patients taking vardenafil most commonly reported headaches, flushing, rhinitis, and dyspepsia. These effects were generally mild to moderate, dose-related, and transient.1
- Headache, back pain, myalgia, and dyspepsia were most commonly reported with tadalafil.13 Similarly, adverse events were mild or moderate, dose-related, and generally abated with treatment.
Treatment-related visual disturbances have been reported in 3% of patients taking sildenafil, >0.1% to <1% of men taking vardenafil, and <0.1% of those taking tadalafil.1 Laboratory parameters have been unaffected by treatment with the PDE-5 inhibitors, and treatment discontinuation due to adverse events has been consistently low.1
All three PDE-5 inhibitors cause vasodilatory effects and are contraindicated in patients using organic nitrates. Consensus guidelines have been developed for using PDE-5 inhibitors in patients with cardiovascular conditions.14
- Rosen RC, Kostis JB. Overview of phosphodiesterase 5 inhibition in erectile dysfunction. Am J Cardiol 2003;92(suppl):9M-18M.
- The Process of Care Consensus Panel. Position paper: the process of care model for evaluation and treatment of erectile dysfunction. Int J Impot Res 1999;11:59-74.
- American Foundation for Urologic Disease. www.afud.org
Drug brand names
- Ketoconazole • Nizoral
- Rifampin • Rifadin
- Ritonavir • Kaletra, Norvir
- Sildenafil • Viagra
- Tadalafil • Cialis
- Vardenafil • Levitra
The author receives research/grant support and is a consultant to and speaker for Eli Lilly and Co. and Pfizer Inc.