As stipulated in the protocol, the primary analysis did not exclude patients with an IIEF EF domain score ≥26 at baseline. A post hoc analysis that excluded 14 patients with “no ED” at baseline resulted in slightly lower baseline and endpoint scores without change in statistical interpretation (Table 2).
A post hoc analysis of efficacy by ED severity group (excluding the 14 patients with “no ED”) showed EF improvement regardless of baseline ED severity (Figs. Tadalafil 5 and 10mg taken once daily significantly improved EF as measured by all secondary efficacy variables.
| Parameter | Value | Description |
|---|---|---|
| Absorption Time | 30-120 minutes | Time to peak plasma concentration |
| Half-life | 17.5 hours | Duration of drug presence in body |
| Bioavailability | ~80% | Fraction of drug absorbed |
| Metabolism | Hepatic (liver) | Mainly via CYP3A4 enzyme |
| Excretion | Feces and urine | Pathways of elimination |
Based on “yes” responses to GAQ, 84.5% (tadalafil 5mg) and 84.6% (tadalafil 10mg) of men thought treatment improved their erections (28.3% of men who took placebo, p<0.001). Of the men who had an IIEF EF domain score <26 at baseline, 51.5% (tadalafil 5mg) and 50.5% (tadalafil 10mg) achieved an EF domain score 26–30 (“no ED”) at endpoint (8.3% of men who took placebo, p<0.001).
The safety evaluation included all 268 enrolled subjects. The mean number of doses per week was calculated as the number of doses taken divided by the number of weeks on therapy until the last scheduled visit.
Patients were instructed to take one dose of study drug around the same time each day. Three efficacy instruments were used: the IIEF EF domain, the Sexual Encounter Profile (SEP) diary, and a Global Assessment Question (GAQ): “Has the treatment you have been taking during this study improved your erections?”. The co-primary efficacy measures were change from baseline in IIEF EF domain score, and change from baseline in per-patient mean percentage of “yes” responses to SEP Question 2 (SEP2, “Were you able to insert your penis into your partner’s vagina?”) and SEP Question 3 (SEP3, “Did your erection last long enough for you to have successful intercourse?”). Secondary efficacy measures were percentage of “yes” responses to the GAQ; and percentage of men who achieved an EF domain score of at least 26 (“no ED”) at endpoint, who had a baseline EF domain score below 26. A post hoc analysis was also done to determine change from baseline in the EF domain score for each baseline ED severity subgroup.
Safety was assessed by evaluating all reported treatment-emergent adverse events, vital signs measurements, electrocardiograms, and standard safety laboratory assessments for all randomized patients. Treatment-emergent adverse events were defined as any adverse event that first occurred or worsened after randomization, and were mapped with the Medical Dictionary for Regulatory Activities. Subjects voluntarily reported adverse events throughout the study. A sample size of 250 patients would give approximately 90% power to detect a significant treatment effect between placebo and the least-effective tadalafil dosing group. All analyses were conducted on an intent-to-treat basis.
Efficacy analyses included all randomized patients who had a baseline measurement and at least one post-baseline measurement. The last observation carried forward imputation methodology was used to replace missing IIEF EF domain scores. For each SEP question, baseline and post-baseline scores were the number of “yes” responses relative to the number of sexual encounters during the run-in and treatment periods, respectively. Proportions of “yes” responses to SEP diary questions were treated as continuous variables. IIEF EF domain, SEP2, and SEP3 were analyzed with an Analysis of Covariance model that included terms of treatment group, pooled site, baseline value for each primary efficacy variable, and baseline-by-treatment interaction (if p<0.10). Subjects on tadalafil took an average of 6.5 doses per week; subjects on placebo took an average of 6.6 doses per week.
| Product | Dosage | Quantity + Bonus | Price | |
|---|---|---|---|---|
| Cialis Generic | 60mg | 90 + 6 Pills | 196.67€ 187.30€ | |
| Cialis Generic | 2.5mg | 270 + 10 Pills | 199.64€ 190.13€ | |
| Cialis Generic | 40mg | 60 + 6 Pills | 130.98€ 124.74€ | |
| Cialis Generic | 40mg | 270 + 10 Pills | 382.19€ 363.99€ | |
| Cialis Generic | 20mg | 20 Pills | 54.72€ 52.11€ | |
| Tadalista Super Active | 20mg | 30 + 6 Pills | 128.09€ 121.99€ | |
| Tadalista Super Active | 20mg | 120 + 16 Pills | 382.15€ 363.95€ | |
| Cialis Generic | 60mg | 180 + 10 Pills | 313.11€ 298.20€ | |
| Cialis Generic | 20mg | 180 + 10 Pills | 254.09€ 241.99€ | |
| Cialis Generic | 5mg | 360 + 10 Pills | 268.08€ 255.31€ | |
| Cialis Generic | 5mg | 180 + 10 Pills | 159.65€ 152.05€ | |
| Cialis Generic | 10mg | 20 Pills | 48.23€ 45.93€ | |
| Cialis Generic | 2.5mg | 30 + 4 Pills | 51.95€ 49.48€ | |
| Cialis Generic | 2.5mg | 10 Pills | 28.51€ 27.15€ | |
| Cialis Generic | 2.5mg | 20 Pills | 40.73€ 38.79€ | |
| Cialis Generic | 20mg | 30 + 4 Pills | 68.05€ 64.81€ | |
| Cialis Generic | 5mg | 270 + 10 Pills | 205.81€ 196.01€ |
The majority (87.3%) of subjects completed the study.
This observation motivated the development of oral inhibitors of phosphodiesterase 5 for this indication: sildenafil citrate (sildenafil), tadalafil, and vardenafil HCl (vardenafil) [2–4]. Before oral agents were introduced, pharmacological ED treatment was limited to penile injections or intraurethral insertion of vasoactive drugs or prostaglandin E1. Although PDE5 inhibitor pharmacotherapy is less invasive and easier to use, sexual activity remains temporally linked to treatment. For all three PDE5 inhibitors, men must take medication on demand before sexual activity [5–7]. Planning sexual activity around taking a pill is burdensome to some patients and their partners [8].
The mean half-life of sildenafil and vardenafil is about four hours [5,6]; the mean half-life of tadalafil is 17.5hours [7]. Tadalafil 10 or 20mg taken on demand is well tolerated and efficacious for up to 36hours in clinical studies [9,10]. This duration may permit men with ED and their partners to disconnect sexual activity from dosing. Historically, tadalafil has been taken on demand at doses of 10 or 20mg. The ability of a drug to reach steady state results from the frequency of administration relative to half-life.
The 17.5-hour half-life of tadalafil makes it an ideal candidate for once daily therapy because steady-state plasma concentrations are attained within five days of daily dosing, and exposure is approximately 1.6-fold greater than after a single dose [11]. If 5-mg and 10-mg doses are taken daily, a cumulative tadalafil plasma exposure equivalent to on-demand doses of 8mg and 16mg, respectively, could be achieved in a few days. Once-a-day dosing and every-other-day day dosing with tadalafil have been compared with on-demand dosing. In one study, 72% of men preferred once-a-day dosing [12], and in another, 42% preferred every-other-day dosing [13]. Neither study compared the efficacy and safety of scheduled dosing with placebo. Nine (3.4%) discontinued because of adverse events (Fig.
To protect against type 1 error caused by comparing two tadalafil doses with placebo, the pairwise p-values that compared treatment groups were adjusted by the method of Dunnett [16]. A logistic regression model that included terms of pooled site, treatment group, EF at baseline, and baseline-by-treatment interaction was used tadalafil over the counter uk to perform secondary analysis to evaluate GAQ at endpoint by treatment group. Only patients who responded to GAQ were included in the analysis. The percentage of patients who attained an IIEF EF score of 26–30 at endpoint was analyzed with a logistic model that included terms of pooled site, treatment group, EF at baseline, and baseline-by-treatment interaction (if p<0.10). Data analyses were performed by the Eli Lilly Global Statistical Science Group.
The first subject was randomized October 2001 and the last completed treatment in March 2002. Of 293 patients screened, 268 were enrolled and 234 completed the study (Fig. Treatment compliance was defined as taking at least 70% of doses between visits; 96.2% (placebo), 94.2% (tadalafil 5mg), and 93.0% (tadalafil 10mg) of patients were compliant. Treatment group demographics were similar at baseline (Table 1). Tadalafil 5 and 10mg taken daily significantly improved EF as measured by all primary efficacy variables (Table 2). One patient in the tadalafil 5mg group with renal cell carcinoma died during the treatment period.
| Patient Age | Duration of Use | Dosage Frequency | Effectiveness Reported |
|---|---|---|---|
| 45 | 3 months | Once daily | Significant improvement |
| 58 | 6 months | Once daily | Moderate improvement |
| 70 | 1 month | Once daily | Mild improvement |
| 52 | 12 months | Once daily | Very positive |
The study investigator determined that his death was unrelated to the drug.
Treatment-emergent adverse events were generally mild to moderate in severity: 53.8% reported as mild and 32.8% reported as moderate. The most common treatment-emergent adverse events reported were dyspepsia, headache, back pain, upper abdominal pain, and myalgia (Table 3).
Thus, the purpose of the current study was to assess the efficacy and safety of once-a-day dosing of tadalafil 5 and 10mg versus placebo as a new treatment regimen for ED. Patients ≥18 years of age, in a monogamous relationship with a female partner, who reported ≥three-month history of ED could be enrolled. Patients and partners had to sign informed consent and agree not to use other ED treatments during the study. Written informed consent was obtained in conformity with the Declaration of Helsinki (revised 1989) and applicable local laws. The ethics committees of all participating institutions approved the final protocol.
Subjects were excluded from enrollment for any of the following: ED caused by other sexual or endocrine disorders such as premature ejaculation or hypogonadism, history of radical prostatectomy (except bilateral nerve-sparing prostatectomy) or other pelvic surgery with subsequent ED, clinically significant hepatobiliary or renal disease, hemoglobin A1c >13%, unstable cardiovascular disease [14], current nitrate use, congestive heart failure, or recent significant central nervous system injuries. Patients who had previously enrolled in any tadalafil tadalafil sale study, and those with prior ineffective treatment with sildenafil were ineligible. This multicenter, randomized, double-blind, placebo-controlled, parallel-group study evaluated the efficacy and safety of once-a-day dosing of placebo, tadalafil 5mg, and tadalafil 10mg, administered for 12 weeks to men with ED from 20 centers from Argentina, Brazil, France, Germany, and the United Kingdom. This study (Lilly ICOS LLC study identifier H6-MC-LVCV) began with a screening period that lasted four to five weeks. Eligible subjects were randomly assigned via central telephone to treatment groups 1:2:2 (placebo:5mg, tadalafil:10mg, tadalafil).
Randomization was stratified by ED severity as measured by the International Index of Erectile Function Erectile Function domain (IIEF EF) [15]. Three stratifications of severity were used: severe (EF domain score 1–10), moderate (11–16), and mild (17–30). Because patients were enrolled based on a history of ED, some men scored 26–30 (“no ED”) [15] at baseline. The protocol stipulated that these men would be included in the mild category. Treatment lasted 12 to 15 weeks and consisted of three visits four to five weeks apart. One patient who took tadalafil 5mg reported an incident of “gritty feeling in the eyes.” There were no incidents of myocardial infarction (MI).