Evaluation of the Efficacy and Safety of Once-a-Day Dosing of Tadalafil 5mg and 10mg in the Treatment of Erectile Dysfunction: Results of a Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

Tadalafil is not recommended in patients with severe hepatic dysfunction. Like other PDE5 inhibitors, tadalafil effectively improves the ability of men with erectile dysfunction to achieve an erection and successfully complete intercourse. It is less effective, although still useful, in some men with ED due to diabetes. Its longer duration may require less frequent dosing and may allow the user to take it earlier in the day of planned sexual activity. However, some authorities suggest that, because the sildenafil safety record is more established, it may be preferred over tadalafil.4 aPrivate Practice of Urology and Andrology, Hamburg, Germany bNeuro-Urology Unit, Department of Neurological Rehabilitation, AP-HP, Raymond Poincaré Hospital, Garches, France eInstituto Médico Especializado (IME), Buenos Aires, Argentina Accepted February 21, 2006; Published online March 21, 2006 DOI: 10.1016/j.eururo.2006.02.052 External LinkAlso available on ScienceDirect External Link Medical management of erectile dysfunction (ED) changed with the observation in 1992 that the nitric oxide-cyclic GMP pathway plays a critical role in erectile function (EF) and defects in this pathway may cause some forms of ED [1].

4 Discussion

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.

2.2 Study design

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. This observation motivated the development of oral inhibitors of phosphodiesterase 5 for this indication: sildenafil citrate (sildenafil), tadalafil, and vardenafil HCl (vardenafil) [2–4].

Product	Dosage	Quantity + Bonus	Price
Cialis Generic	20mg	20 Pills	54.72€ 52.11€	Buy
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Cialis Professional	40mg	30 Pills	148.94€ 141.85€	Buy
Cialis Original	20mg	12 Pills	78.32€ 74.59€	Buy
Cialis Generic	20mg	60 + 6 Pills	117.76€ 112.15€	Buy
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Cialis Professional	20mg	10 Pills	48.29€ 45.99€	Buy
Cialis Generic	60mg	120 + 8 Pills	240.18€ 228.74€	Buy
Cialis Generic	5mg	360 + 10 Pills	268.08€ 255.31€	Buy
Cialis Soft Tabs	20mg	90 + 6 Pills	216.71€ 206.39€	Buy

Before oral agents were introduced, pharmacological ED treatment was limited to penile injections or intraurethral insertion of vasoactive drugs or prostaglandin E1.

5.9 Alcohol

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 daily cialis price 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.

Professional resources

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). 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].

12.1 Mechanism of Action

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. 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). 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.

Parameter	Description	Notes
Effect on erectile function	Improves ability to achieve and sustain erection	Most effective within 30-60 mins
Response rate	About 80% of users find it effective	Varies by individual
Onset time	Usually within 30 minutes	Depends on food intake
Duration	Up to 36 hours	Long-lasting, effective window
Onset variation	Faster on empty stomach	Slower if taken after heavy meals

Historically, tadalafil has been taken on demand at doses of 10 or 20mg.

Is There A Difference Between Tadalafil and Cialis?

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.

Incidence not known

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. 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.

• Cialis 10 mg helps increase blood flow to the penis.
• It is not an aphrodisiac; arousal is needed.
• Take Cialis about 30 minutes before sexual activity.
• The medication is effective regardless of food intake.
• A dose adjustment may be necessary for liver issues.
• Men should not plan to take Cialis more than once daily.
• Cialis has been approved by health authorities worldwide.
• Some users report improved erectile quality.
• Cialis may cause muscle pain or nasal congestion.
• Consult your doctor to confirm if Cialis is safe for you.
• Keep out of reach of children and stored properly.

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. 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.

14.1 CIALIS for Use as Needed

Tadalafil is not recommended in patients with severe hepatic dysfunction. Like other PDE5 inhibitors, tadalafil effectively improves the ability of men with erectile dysfunction to achieve an erection and successfully complete intercourse. It is less effective, although still useful, in some men with ED due to diabetes. Its longer duration may require less frequent dosing and may allow the user to take it earlier in the day of planned sexual activity. However, some authorities suggest that, because the sildenafil safety record is more established, it may be preferred over tadalafil.4 aPrivate Practice of Urology and Andrology, Hamburg, Germany bNeuro-Urology Unit, Department of Neurological Rehabilitation, AP-HP, Raymond Poincaré Hospital, Garches, France eInstituto Médico Especializado (IME), Buenos Aires, Argentina Accepted February 21, 2006; Published online March 21, 2006 DOI: 10.1016/j.eururo.2006.02.052 External LinkAlso available on ScienceDirect External Link Medical management of erectile dysfunction (ED) changed with the observation in 1992 that the nitric oxide-cyclic GMP pathway plays a critical role in erectile function (EF) and defects in this pathway may cause some forms of ED [1].

Drug details

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]. 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 buy cialis over the counter with the Declaration of Helsinki (revised 1989) and applicable local laws.

Daily Intake

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 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.

Does Cialis work and is it safe?

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). 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 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.

Country/Region	Approval Status	Regulatory Body
United States	Approved by FDA for ED	Food and Drug Administration
European Union	Approved CE mark	European Medicines Agency
Canada	Approved Health Canada	Health Canada
Australia	Approved Therapeutic Goods Administration	TGA
India	Approved by DCGI	Drug Controller General of India

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. 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.

• Cialis 10 mg dosage may be adjusted by doctors.
• It is effective in males with reduced libido.
• Cialis begins working within 30 minutes in most cases.
• It boosts confidence during intimate moments.
• The medication isn’t suitable for women.
• Keep track of your response to the medication.
• Cialis can be part of ED management strategies.
• Avoid taking multiple doses in a 24-hour period.
• The medication is approved by multiple health agencies.
• Consult a doctor if you experience dizziness.
• Cialis should be used responsibly with medical guidance.

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 daily cialis price 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.

• 10 mg Cialis is a prescribed medication for erectile dysfunction.
• It is the lowest available dose of Cialis.
• Cialis contains the active ingredient tadalafil.
• It typically works within 30 minutes to 2 hours.
• The effects can last up to 36 hours.
• Cialis 10 mg should be taken with water.
• It is usually taken about 30 minutes before sex.
• Do not exceed one dose per day.
• Consult a healthcare provider before use.
• Cialis can cause side effects like headache and flushing.
• Do not take with nitrates or certain medications.

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). 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 to perform secondary analysis to evaluate GAQ at endpoint by treatment group. Only patients who responded to GAQ were included in the analysis.

5.10 Concomitant Use of Potent Inhibitors of Cytochrome P450 3A4 (CYP3A4)

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 buy cialis over the counter with the Declaration of Helsinki (revised 1989) and applicable local laws. The ethics committees of all participating institutions approved the final protocol.

Dosage for benign prostatic hyperplasia (BPH)

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 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). 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.

• Cialis 10 mg is available in tablet form.
• It is non-urgent, planned use enhances experience.
• Be cautious about interactions with antihypertensives.
• The drug can cause mild stomach upset.
• Cialis’s effects can improve quality of life.
• Men should follow the doctor’s instructions strictly.
• It can be discontinued if it causes problematic side effects.
• Cialis is a prescription-exclusive medication.
• Check expiration dates before use.
• Use caution when driving or operating machinery.
• Always talk with your healthcare provider first.

Treatment group demographics were similar at baseline (Table 1).

Side Effect	Frequency	Severity	Notes
Headache	Common	Mild to moderate	Usually temporary
Flushing	Common	Mild	Facial redness
Indigestion	Less common	Mild	Related to gastrointestinal
Muscle pain	Rare	Mild	Transient
Nasal congestion	Less common	Mild	Temporary

Tadalafil 5 and 10mg taken daily significantly improved EF as measured by all primary efficacy variables (Table 2). 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. 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).