Introduction
Erectile dysfunction (ED) is a complex disorder characterized by the persistent inability to achieve or maintain satisfactory erections for sexual activity. It is far from rare; prevalence estimates range from 20% to 41% globally, with age acting as the strongest predictor. In China, approximately 40% of men over 40 years suffer from ED, with prevalence escalating steeply after 70 years of age. Although ED is not life-threatening, its impact is profound, touching on intimate relationships, psychological well-being, and overall quality of life.
Phosphodiesterase type 5 (PDE5) inhibitors have revolutionized ED management since their introduction, providing rapid and effective relief. Tadalafil, with its long half-life and once-daily dosing option, has distinguished itself among PDE5 inhibitors. Initially developed as an on-demand medication, tadalafil has increasingly been prescribed for continuous daily use, offering men the freedom of spontaneity in sexual life. While robust efficacy and safety data exist for Western populations, evidence in Chinese men has historically been limited. Differences in genetics, comorbidities, and treatment patterns between populations underscore the need for region-specific research.
A recent multicenter, randomized, open-label, post-marketing trial addressed this gap. Conducted across 24 centers in China, it followed over 600 men with ED for two years, evaluating the safety, efficacy, and patient-reported outcomes of daily tadalafil therapy. This long-term study provides valuable insights into how Chinese men respond to daily tadalafil—insights that extend beyond clinical metrics into quality of life and sexual satisfaction.
Study Design and Methodology
The trial enrolled 635 Chinese men aged 22 to 70 years, each with at least a three-month history of ED and a stable heterosexual relationship. Exclusion criteria were stringent, filtering out men with untreated endocrine disease, major cardiac conditions, renal or hepatic impairment, uncontrolled diabetes, or those on medications known to interact with tadalafil. This design ensured a relatively homogeneous population, appropriate for evaluating tadalafil without excessive confounding.
Participants were randomized to receive either 2.5 mg or 5 mg tadalafil once daily for the initial 3 months. After this period, all patients transitioned to a standardized regimen of 5 mg daily for the remaining 21 months. Follow-up occurred at months 1, 3, 6, 12, 18, and 24, with rigorous monitoring of both efficacy and safety endpoints.
The primary efficacy measure was the International Index of Erectile Function–Erectile Function (IIEF-EF) domain score, the gold standard for quantifying erectile performance. Secondary endpoints included the Global Assessment Questionnaire (GAQ), the Sexual Life Quality Questionnaire (SLQQ), and treatment satisfaction scores. Safety endpoints encompassed treatment-emergent adverse events (TEAEs), treatment-related adverse events (TRAEs), and serious adverse events (SAEs).
By employing both objective clinical scales and subjective patient-reported outcomes, the trial captured a holistic picture of tadalafil’s long-term effects, reflecting not only physiological improvement but also personal and relational satisfaction.
Efficacy Outcomes: Erectile Function Restoration
From the very beginning of therapy, tadalafil demonstrated rapid benefits. Baseline IIEF-EF scores averaged 15.4, reflecting moderate erectile dysfunction. Within the first month, scores had risen significantly to 21.2, already edging many men toward functional normality. Continued improvement was observed over the study period, with mean scores climbing to 23.6 at 12 months and 24.3 at 24 months. These improvements were not transient fluctuations but durable gains sustained across two full years of daily therapy.
By the end of the trial, 48% of men had regained normal erectile function, defined as IIEF-EF scores of 26 or higher. This figure is clinically meaningful: nearly half of the study population transitioned from compromised function to normal erectile capacity, a transformation that cannot be understated in its personal and relational impact.
Importantly, the GAQ data corroborated these findings. At 12 months, 97.5% of participants reported improved erection function, and 95.9% reported improved ability to engage in sexual activity. These rates remained consistently high at 24 months, highlighting that improvements were not merely measurable on scales but palpably felt by the men and their partners.
Quality of Sexual Life and Satisfaction
Beyond erectile function, sexual quality of life represents the true litmus test of success. Sexual performance without satisfaction is, after all, a hollow victory. The SLQQ scores told a compelling story: quality of sexual life improved by 45.8% after three months, rose further to 52.2% at one year, and peaked at 55.3% by the end of two years. Such steady upward progression suggests that the benefits of tadalafil extend well beyond mechanics to encompass confidence, spontaneity, and relational intimacy.
Treatment satisfaction followed a similar trajectory. Scores averaged 59.2 at three months, climbed to 62.4 at one year, and reached 65.9 at two years. This upward momentum contrasts with the waning enthusiasm often seen in chronic therapies where side effects or diminishing efficacy erode compliance. Here, the opposite occurred: satisfaction grew with time, a testament to tadalafil’s durable performance and tolerability.
For many patients, the greatest advantage of daily dosing was not merely the pharmacological effect but the liberation from planning. Unlike on-demand regimens, which tether sexual activity to medication timing, daily tadalafil restored natural spontaneity—a subtle but profound shift in quality of life.
Safety Profile and Adverse Events
No discussion of long-term pharmacotherapy is complete without addressing safety. Over the 24 months, 42.9% of participants reported TEAEs. The most common were viral respiratory tract infections (9.0%), upper respiratory tract infections (4.4%), and headaches (2.4%). TRAEs were infrequent, with headache and dizziness topping the list, and only 1.7% of participants discontinued therapy due to adverse events.
Cardiovascular concerns, often cited with PDE5 inhibitors, were relatively uncommon. By 24 months, cardiovascular TEAEs occurred in only 4% of participants, the majority being mild. Serious adverse events affected 5.1% of men, with only one case—an allergic rhinitis—possibly attributable to tadalafil. One death occurred due to myocardial infarction, though causality with tadalafil was not established.
These data reaffirm tadalafil’s favorable safety profile, even with prolonged daily exposure. Crucially, the incidence of side effects did not escalate dramatically with time. TEAEs were reported in 27.3% during the first year and 42.9% after two years, a modest increase given the extended duration. No new or unexpected safety signals emerged, underscoring the drug’s suitability for long-term use.
Compliance and Real-World Relevance
Adherence is the Achilles’ heel of many chronic therapies. Men may discontinue treatment due to lack of efficacy, intolerable side effects, or the inconvenience of dosing regimens. In this study, however, compliance rates were high: 82.7% during the randomization phase and 88.5% during the long-term extension. Nearly three-quarters of participants completed the full two years of therapy, a remarkable figure in real-world settings.
The key driver of compliance was not merely efficacy but the combination of rapid onset, durable benefits, tolerability, and the freedom of spontaneity. Patients no longer had to plan intimacy around pill ingestion. Instead, they could rely on continuous readiness, which likely contributed to the high satisfaction scores and long-term persistence.
These findings carry practical significance for clinicians. When counseling men with ED—particularly those skeptical of chronic pharmacotherapy—daily tadalafil offers not just improved erections but an enhanced lifestyle. Compliance becomes less a burden and more a natural consequence of sustained satisfaction.
Limitations and Areas for Future Research
While the study’s strengths are clear—large sample size, multicenter design, and long follow-up—it also has limitations. First, it excluded high-risk groups such as men with severe cardiovascular disease, advanced diabetes, or endocrine disorders, limiting generalizability. Second, stratified analyses by ED severity, comorbidities, or prior treatment history were not comprehensively performed, leaving unanswered questions about subgroup responses. Third, while the trial documented impressive efficacy and safety, it did not compare daily tadalafil against on-demand regimens in a head-to-head fashion within the same population.
Future studies should address these gaps. Stratified trials could clarify whether elderly patients or those with diabetes derive equal benefit and tolerability. Comparative trials could illuminate whether daily dosing truly outperforms on-demand strategies in terms of long-term satisfaction and compliance. Moreover, mechanistic research into tadalafil’s potential vascular protective effects may reveal benefits beyond erectile function, particularly in populations at cardiovascular risk.
Conclusion
The two-year trial of daily tadalafil in Chinese men with ED delivers a clear message: tadalafil 5 mg once daily is safe, effective, and well tolerated, with benefits extending beyond erectile function to encompass quality of life, satisfaction, and long-term adherence. Nearly half of participants regained normal erectile function, while the vast majority reported improved performance and satisfaction. Adverse events were mild and manageable, compliance was high, and no new safety concerns emerged.
For clinicians, these findings support daily tadalafil as a robust therapeutic option for men with ED seeking long-term, spontaneous sexual activity. For patients, it offers more than an erection—it restores confidence, intimacy, and quality of life. In the realm of sexual medicine, that is no small achievement.
FAQ
1. Is daily tadalafil more effective than taking it only when needed?
Both regimens improve erectile function, but daily tadalafil provides consistent readiness for sexual activity without the need to plan ahead. This often translates to greater satisfaction and better compliance, especially over the long term.
2. Is it safe to take tadalafil every day for years?
Yes. This two-year study in Chinese men demonstrated a favorable safety profile with no new concerns. Most side effects were mild, and only a small fraction of patients discontinued therapy due to adverse events.
3. How soon can improvements be expected with daily tadalafil?
Most men experienced significant improvements within the first month, with continued gains over time. By the end of two years, nearly half had regained normal erectile function, and the majority reported improved sexual satisfaction and quality of life.
