Tadalafil and vardenafil vs sildenafil: a review of patient-preference studies.

The immediate objective of phosphodiesterase type 5 (PDE5) inhibitor treatment is to restore the ability of a man to achieve and/or maintain an erection adequate for sexual intercourse. As erectile dysfunction (ED) generally develops in the second half of life, the ultimate objective generally is not procreation, but quality of sexual life. Indeed, ED is known to impair quality of life considerably; two-thirds of men report that ED has impaired their self-esteem and nearly a third claim that it has damaged the relationship with their partner. It follows that the therapeutic success of PDE5 inhibition has an important subjective component, which is compounded by the subjective nature and complexity of sexual life in humans. This makes it very difficult for physicians to be certain that they have selected the optimal therapy for a couple, even after a thorough evaluation. The 2007 European Association of Urology Guidelines stress the importance of educating the patient and claim that 'the patient will choose the final drug after his own experience'. However, PDE5 inhibitors are typically used twice a week, so a patient would have to spend approximately 3 months trying the various compounds and dosages to achieve adequate exposure to all three PDE5 inhibitors; this would seem an unrealistic strategy in normal clinical practice. The acknowledgement that the patient has an important role in therapeutic decisions for ED has fuelled interest in the concept of patient preference. It has been established that patient preference depends on three factors, i.e. personal characteristics, e.g. age, duration of ED, frequency and dynamics of sexual relations, and the characteristics of their partners, e.g. age, menopausal status and level of interest in sexual activity and medication profile. Medication features of interest include efficacy in terms of quality of erection, consistency of effects, rapid onset of action, long duration of action, side-effect profile and route of administration; drug costs must also be considered if the medicinal product is not reimbursed.