What the as-needed program counted
The label says efficacy and safety of tadalafil for erectile dysfunction were evaluated in 22 clinical trials of up to 24 weeks, involving over 4,000 patients. As-needed Cialis, up to once a day, improved erectile function in men with erectile dysfunction.
Seven of the main studies were randomized, multicenter, double-blind, placebo-controlled, and 12 weeks long, in the general ED population. Two were run in the United States and five outside the United States. Further studies enrolled men with diabetes and men with erectile dysfunction after bilateral nerve-sparing radical prostatectomy. In the seven general-population trials the dose ranged from 2.5 to 20 mg, up to once a day. Men chose the gap between the tablet and the attempt. Food and alcohol were not restricted.
The three primary measures were the erectile-function domain of the International Index of Erectile Function and two diary questions. The domain is a 4-week recall score with a 30-point total. Higher is better function. Sexual Encounter Profile question 2 asks whether insertion was possible. Question 3 asks whether the erection lasted long enough for successful intercourse. A personal result is not the mean of those diaries.
Two US trials at 20 mg
In the two primary US trials the label's table lines up Study A and Study B, each with a placebo column and a Cialis 20 mg column. Erectile-function endpoints were 13.5 and 19.5 in Study A (placebo, then 20 mg) and 13.6 and 22.5 in Study B. Change from baseline was -0.2 and 6.9 in Study A, and the next pair on that change row is 0.3 and 9.3. The label marks those 20 mg differences from placebo as statistically significant. The treatment effect did not diminish over time inside the study window.
Read the columns in that order. A single "about 20" floating free of placebo is how a forum turns a 6.9-point change into a promise. The score still sat in the teens and low twenties at the end, on a 30-point scale, in men who were already in a trial.
Maintenance of erection (the third diary question) ended at 25% and 50% in Study A and 23% and 64% in Study B, placebo then 20 mg. Insertion rates moved as well. The integrated as-needed summary, across 10 mg and 20 mg, put successful intercourse attempts at 33% on placebo, 56% on 10 mg, and 62% on 20 mg. That summary and the two US tables are the same program seen at two zooms. They are not a contest with the daily tablet. The daily-versus-as-needed choice is on Cialis daily versus as needed.
Diabetes and post-prostatectomy studies are named. This label passage does not paste the general-ED point change onto those groups. If that is the situation, the prescriber is looking at a different row from Study A.
The 24-hour and 36-hour attempts
One timing study told men to attempt intercourse at an assigned hour. At 24 hours, the mean per-patient percentage of attempts that led to successful intercourse was 42% on placebo, 56% on 10 mg, and 67% on 20 mg. The difference versus placebo was statistically significant at the prespecified times in that study.
A separate count, at 33 to 39 hours after the dose, found at least one successful intercourse in 49 of 133 men on placebo (37%) and 88 of 137 men on 20 mg (64%). That is the 36-hour figure in human units: more men in the 20 mg group had a successful attempt in that late window. It is not an erection that runs for 36 hours, and the once-a-day cap still applies. Some form of sexual stimulation is required.
The nitrate study is a blood-pressure study
A clinical-pharmacology study gave tadalafil 20 mg or placebo once a day for 7 days, then a single 0.4 mg sublingual nitroglycerin at set hours. A significant interaction showed up at each timepoint through 24 hours. At 48 hours, by most hemodynamic measures, the interaction was not observed, although a few more tadalafil subjects than placebo subjects had a greater blood-pressure drop at that point. After 48 hours the interaction was not detectable.
The label's next sentence is the rule, not a loophole. Cialis administration with nitrates is contraindicated. In a life-threatening situation the wait before a nitrate is considered is at least 48 hours, under monitoring. "Most measures looked quiet at 48 hours" still leaves a few men with a larger drop, which is why the contraindication does not expire on a kitchen clock. Chest pain is emergency care.
Daily trials and the urinary score
Once-daily Cialis for erectile dysfunction was evaluated in two trials of 12 weeks and one trial of 24 weeks, 853 patients in all. Taken once daily, it improved erectile function. Those trials are the evidence for the 2.5 mg and 5 mg daily schedule. They do not reuse the 20 mg US table.
For benign prostatic hyperplasia, two once-daily studies (the label's Study J and Study K) used the International Prostate Symptom Score, a 0-to-35 score in which a higher number is a worse mix of frequency, urgency, nocturia, and a weak stream. Men had moderate to severe symptoms and a mean age of 63.2 years. Cialis 5 mg once daily improved the total score versus placebo in both trials. In the printed change row, week-12 changes include -2.2 and -4.8. Baseline scores on that table sit around 17. A drop of a few points is a real shift in the trial and a modest one on a 35-point scale. It is not a substitute for a procedure when retention or infection is the problem.
Maximum flow rate was a secondary endpoint in Study J. This note does not promote a flow number the symptom score already outranks as the primary result.
How to use a row without inventing a winner
A p-value says the group difference was unlikely to be noise under that protocol. It does not say the next man will gain 6.9 points. Food was unrestricted in the as-needed efficacy studies, which matches the later instruction that food does not change absorption. Alcohol was unrestricted there too, which is not permission to drink heavily. The warnings section still flags substantial alcohol because of blood pressure.
Adcirca is tadalafil for a different labeled use. The Cialis studies section here is erectile dysfunction and prostate symptoms. Combining Cialis with other PDE5 inhibitors, including Adcirca, was not studied. A pulmonary-hypertension walk test does not belong on this page.
The development calendar, including the 2003 US approval year printed on this label, is on how Cialis was developed. The fill, the imprint, and the pharmacy check are on the tadalafil medicine page. Julian Frost signs this note. The limit of a reading note is on the margin disclaimer. The label text is the Lilly CIALIS entry on DailyMed.