Pharmacokinetics, pharmacodynamics, and efficacy of phosphodiesterase type 5 inhibitors

Clinical evidence in men with erectile dysfunction (ED) shows that the phosphodiesterase type 5 (PDE5) inhibitors sildenafil citrate, tadalafil, and vardenafil hydrochloride have favorable safety and efficacy profiles. However, as mild vasodilators, the PDE5 inhibitors are also associated with hemodynamic effects that may be clinically significant, especially when treating men with ED who have comorbid cardiovascular disease. Hemodynamic studies have shown that therapeutic dosages of the PDE5 inhibitors produce only mild and transient changes in mean systolic and diastolic blood pressure and heart rate in healthy men as well as those with ischemic heart disease or chronic stable angina. Overall, PDE5 inhibitors are safe and effective in most patient populations, including men with ischemic cardiovascular disease or those receiving anti-hypertensive agents, and men with diabetes or those who have undergone nerve-sparing retropubic radical prostatectomy. With the entry of three novel PDE5 inhibitors into the therapeutic armamentarium for ED, differentiating properties of the new agents may confer clinical benefits that physicians as well as patients and their partners should consider when selecting a PDE5 inhibitor.