Past, present, and future:: a 7-year update of Viagra® (sildenafil citrate)

More than 30 million men are estimated to have erectile dysfunction (ED) in the United States (Feldman et al. J Urol 1994;151: 54-61). Worldwide, ED is estimated to affect more than 150 million men, and that number is expected to exceed 300 million men by the year 2025 (Aytac et al. BJU Int 1999;84: 50-6). The prevalence of ED ranges from 7% in men aged 18-29 years (Laumann et al. JAMA 1999;281: 537-44) to 85% in men aged 76-85 years. In addition, a recent report showed that 68% of patients with ED aged 18 years and older have at least one comorbid diagnosis of hypertension, hyperlipidaemia, diabetes or depression (Seftel et al. J Urol 2004;171: 2341-5), and research suggests that ED may be an early indicator of systemic vascular disease (Kaiser et al. J Am Coll Cardiol 2004;43: 179-84). Viagra((R)) (sildenafil citrate), the first-in-class phosphodiesterase type 5 (PDE5) inhibitor, was introduced in 1998 for the treatment of ED (Boolell et al. Br J Urol 1996;78: 257-61; Boolell et al. Int J Impot Res 1996;8: 47-52). In the 7 years since its market launch, more than 750,000 physicians have prescribed sildenafil to more than 23 million men, helping establish an excellent safety and efficacy record. Clinical studies have demonstrated that sildenafil successfully treats ED of varied organic, psychogenic or mixed aetiology, and is effective in men with ED and comorbidities such as hypertension, hyperlipidaemia, diabetes or depression. Sildenafil was a breakthrough medication that addressed a previously unfulfilled medical need. The impact of sildenafil has stimulated academic, clinical and industrial research to better understand the nature of sexual function and develop better treatment and management for sexual dysfunctions such as ED. With the advent of other erectogenic therapies for the treatment of ED, this 7-year update will focus on the unique history and development of sildenafil, its current use and applications and its future directions and indications. Special emphasis is placed on the impact of sildenafil on our understanding of sexual health and on the extensive safety and efficacy data that have been amassed from numerous clinical trials.