The papers say most men improve. What are my odds if I have diabetes?
A trial row can move a score and still hide the hold
Registrational ED packs exclude men on organic nitrates.
So the IIEF table never has to show what the spray would have done.
That exclusion is not a scandal. It is how you keep a Phase III room from becoming a hypotension ward. It does mean the pretty IIEF column is a selected room. The man with a GTN spray in his jacket never sat in that chair. Quoting a high success rate at a man on isosorbide is literacy used badly.
I circle the empty nitrate cell before I circle the p-value. The Lilly Cialis prescribing information still opens contraindications on any form of organic nitrate, regular or intermittent. Clinical pharmacology showed tadalafil potentiates the hypotensive effect. The trial row did not have to demonstrate that again. The label already knew.
Peer line: when a patient brings a printout of success rates, I ask for the inclusion page. If nitrates are in the exclusion list - they always are - the printout is not about him until the spray is gone. The tadalafil medicine page keeps that hold in plain type. This library note is about why the evidence tables look so clean.
The same silence applies to riociguat and to the rare man who needs a nitrate in a crash bay after a Friday 20 mg. Those stories live in warnings, not in Brock's 12-week mean.
IIEF, SEP, GAQ - three ways to ask the same night
Rosen's IIEF is a 15-item self-report. The erectile-function domain, six questions, scores 6 to 30. Twenty-six and above is the usual 'normalized' cut. Mild, mild-to-moderate, moderate, severe - those bands are how papers describe the room they started with. A mean rise of 7 points is not a personality change. It is a domain shift on a questionnaire.
SEP is a diary after the attempt. SEP-Q2 asks whether penetration happened. SEP-Q3 asks whether the erection lasted long enough for intercourse. I trust SEP-Q3 more than a hallway adjective. It is still a night, still a partner, still a mood. Binary ticks lie less than 'it was better.'
GAQ is the blunt summary: did treatment improve your erections? Useful for a global nod. Easy to over-quote. I never let a GAQ percentage stand in for a nitrate history.
These instruments are why ED evidence looks so portable. They are also why people forget the exclusion list. A score cannot record a spray that was never allowed in the building.
Brock 2002: five trials, 1112 men, 10 and 20 mg in the light
Integrated analysis, 74 centers, 12 weeks, on-demand dosing.
Mean age 59. Organic ED in about three-fifths.
Brock's 2002 integrative analysis is the sheet I still pull first. Five randomized, double-blind, placebo-controlled Phase III trials. 1112 men. Doses from 2.5 to 20 mg before intercourse, once a day at most. Baseline mix: about 41 percent mild, 23 percent moderate, 36 percent severe. Organic etiology in 61 percent.
IIEF-EF rose 6.5 points on 10 mg and 7.9 on 20 mg, against 0.6 on placebo. SEP-Q3 successful-attempt rates improved 34 percentage points on 10 mg and 39 on 20 mg, against 6 on placebo. GAQ 'improved erections' hit 81 percent on 20 mg against 35 percent on placebo. Complete 'normalization' to IIEF-EF 26 or higher: 59 percent on 20 mg versus 11 percent on placebo. Those are the numbers I write in the margin. They are not a promise to the man in front of me.
More than 70 percent of attempts succeeded from 30 minutes through 36 hours after dosing in that pack. That sentence is the duration claim in trial language. It is also the sentence ads flattened. Responsiveness across a window is not a continuous erection and it is not a nitrate clearance.
Carson 2004 stacked six more trials on top of Brock - 11 studies, 10 and 20 mg only. IIEF-EF +6.5 and +8.6 versus +0.9 placebo. SEP-Q3 totals about 58 percent on 10 mg and 68 percent on 20 mg versus 31 percent on placebo. Same shape, bigger room. Still no spray in the chairs.
Porst's 36 hours is not Kloner's 48
Porst's AUA 2002 data, then the 2003 paper, are why the label may say improved function up to 36 hours after a PRN dose. That clock is an efficacy clock. It asks: with stimulation, did the attempt still work this many hours later?
Kloner's nitrate time-course is a different clock. Organic nitrates donate nitric oxide. PDE5 blockade lets cGMP pile up. Blood pressure can fall hard. The interaction is a class rule. Because tadalafil lingers, the teaching wait is longer than sildenafil's old 24-hour rule. Label language: if a nitrate is deemed medically necessary in a life-threatening setting, at least 48 hours after the last Cialis dose, and then only with close hemodynamic monitoring. Chest pain after a tablet is an emergency-room trip, not a home spray.
I write both numbers on the same card and underline the jobs. 36 = bedroom window. 48 = crash-cart wait. Residents who fuse them will clear a nitrate too early or tell a couple the tablet has 'worn off' at hour 37 when the enzyme is still busy.
The ICOS-to-Lilly history note explains why the long clock existed to be measured. This page only refuses to let the measurement erase the hold.
Diabetes and nerve rows still moved - smaller, not zero
Sáenz de Tejada 2002: 216 men with diabetes, mostly type 2, mean IIEF-EF about 12 going in, many with HbA1c over 7. Tadalafil 10 mg and 20 mg raised IIEF-EF by 6.4 and 7.3 against 0.1 on placebo. Successful intercourse improved about 28 and 29 percentage points against 1.9. GAQ improved-erection nods: 56 and 64 percent against 25. Smaller room than the mixed Brock pack. Still a real separation.
Post-prostatectomy and radiotherapy rows exist. Magnitude drops when the cavernosal nerves are injured. I tell those men the questionnaire will move less and the first four to eight attempts still matter. Declaring failure after one anxious Friday is how a useful 20 mg gets abandoned.
Tertiary-care rooms with more severe organic ED, more hypertension, more lipids - Carson 2005 among them - still show IIEF and SEP separation on 20 mg. The pattern is boring on purpose. The drug works across etiologies. The size of the move tracks how much nerve and artery you still have.
None of those rooms enrolled a nitrate. I will keep saying that until it bores you. Boredom is safer than a faint in a bathroom.
Daily 2.5 and 5 mg, BPH 5, PHIRST 40 - other instruments
Once-daily ED evidence is a later, lower-exposure pack.
Do not paste a 20 mg PRN SEP onto a 5 mg morning swallow.
Porst, Rajfer, Hatzichristou, McMahon - those names sit on the once-daily ED pack. FDA stamp January 2008. Start 2.5 mg at the same time each day, step to 5 mg. Steady state in about five days. Forgue's PK work: daily exposure about 1.6-fold the same milligram taken now and then, so a 2.5 mg daily trough is not a 2.5 mg PRN night. Different strategy. The PRN versus daily ledger is where I spend the lifestyle argument. Here I only mark that the daily IIEF still beat placebo.
BPH at 5 mg once daily, 2011, uses IPSS. The move is real and modest. The gland does not shrink. Peak flow is not the star. Best clinical fit is the man who already has ED and bother - one swallow, two labels. Alpha-blocker plus tadalafil for BPH as a stacked hypotensive pair is the combination the label does not want. Tadalafil alone for BPH is allowed. That distinction is how people get hurt in a sentence that was too short.
PHIRST - not a pulse acronym I will not invent - is Galiè 2009 in Circulation. 405 adults with PAH, 16 weeks, tadalafil 2.5, 10, 20, or 40 mg daily versus placebo. The 40 mg arm, later Adcirca, added about 33 meters to the six-minute walk (placebo-corrected), more in bosentan-naive patients, and cut clinical worsening. That is a pulmonary clinic paper. It is not a bedroom paper. 40 mg is not a Cialis 20 mg double.
Class efficacy is close. Kinetics and the hold are not
| Drug | Usual PRN start | Half-life | Food | Nitrate teaching wait |
|---|---|---|---|---|
| Sildenafil | 50 mg (label range 25-100) | ~4 h | Fatty meal blunts | ~24 h (older teaching) |
| Vardenafil | 10 mg (label range 5-20) | ~4-5 h | Fatty meal blunts | Class hold; see that label |
| Tadalafil | 10 mg, up to 20 mg | ~17.5 h | None | At least 48 h, then monitor |
Head-to-head, dose-optimized sildenafil and tadalafil move IIEF in the same neighborhood. I do not sell 'stronger.' I sell fit. Food-sensitive short window versus food-neutral long window. Daily lane versus no daily lane. A 48-hour nitrate wait versus a shorter sildenafil teaching wait. Those are the rows that actually change a prescription.
I keep a pocket grid for the three common PDE5 names. It is a kinetics card, not a trophy.
Read the empty cell before you quote the delta
ED evidence for Cialis 10 and 20 mg PRN is broad, repeatable, and honest about smaller moves in diabetes and nerve injury. Duration is the genuine differentiator in those packs. Peak is not a trophy.
BPH evidence is a modest IPSS shift at 5 mg daily. PAH evidence is one pivotal walk-distance trial at 40 mg. Do not cross-apply the percentages.
The empty nitrate cell is the cell I grade. If your own clinician has not seen the spray, the isosorbide, the chest-pain plan, the trial printout is decoration. Bring that list in. This desk will not write your tablet.
Reader mail
Reader questions on this article
Answered by Dr. Julian Frost, MD · Urology & men's sexual health
Evidence-desk mail. I will quote a row. I will not clear your spray from here.
Lower than the mixed Brock room, still better than placebo. Sáenz de Tejada's diabetes pack saw IIEF-EF rises around 6 to 7 points on 10 and 20 mg, and GAQ improvement in roughly six in ten men, not eight in ten. Poor control and neuropathy shrink the move further. I still offer a proper PRN trial - several attempts, stimulation, 10 mg first unless your own clinician has a reason to start elsewhere - before I call the class a miss. A single anxious night is not a trial.
Why do you keep saying the trials skipped nitrates? Is that a trick in the methods?
It is protection, not a trick. You cannot randomize a man on isosorbide to a PDE5 tablet and call it ethical. So the IIEF table is a nitrate-free room. The contraindication lives in pharmacology studies and in the label, not in the 12-week mean. If you use a spray, a patch, or an oral nitrate even now and then, you are not in Brock's denominator. I will not pretend a printed success rate applies to you until that drug is gone and your own clinician has said so.
Is 20 mg proven better than 10 mg, or do people just ask for the bigger almond?
In Brock and Carson the 20 mg row moves IIEF and SEP a bit more than 10 mg. That is a group mean, not your night. The label still starts most men at 10 mg PRN and steps on effect and tolerability. Back ache and headache also sit on the higher dose. I would rather step a responder than start every man at 20 mg because an ad showed the bigger stamp. CYP3A4 inhibitors cap you at 10 mg every 72 hours anyway.
What is this 40 mg Adcirca number doing in an erection conversation?
It should not be in an erection conversation except as a warning. PHIRST tested tadalafil 40 mg daily for PAH and moved a six-minute walk by about 33 meters versus placebo. Different clinic, different endpoint, different brand. You do not build 40 mg out of two Cialis 20 mg PRN almonds and call it pulmonary therapy. You do not cut Adcirca for a Friday night. If someone sold you that arithmetic, stop and see a clinician who treats the actual disease.
Can I take tadalafil if I already use a blood-pressure tablet that is not a nitrate?
Often yes, with a full list in front of a prescriber who can see you. Alpha-blockers need caution because two vasodilators stack. The BPH-specific warning is about using tadalafil plus an alpha-blocker as dual therapy for prostate symptoms - not a ban on tadalafil for a man who has BPH. Nitrates and riociguat are the hard stops. I cannot clear your combination from a mail thread. Bring the bottles.
How many tries before I decide 10 mg did nothing?
Several separate attempts - I usually want four to eight - at a labeled dose, with stimulation, without a second tablet that day, before I change the plan. Write down timing and whether you were actually aroused. Food is not the usual tadalafil villain. Anxiety and a one-night verdict are. If 10 mg is a true miss, 20 mg is the labeled step, not a new drug. If 20 mg is a miss, we talk etiology, not a third almond from a banner.
Is tadalafil actually better than Viagra in the trials, or just longer?
Mostly longer. Dose-optimized head-to-heads sit in the same IIEF neighborhood. 'Better' is a lifestyle word: a 36-hour window, no fatty-meal penalty, a later daily lane, a longer nitrate wait. If you need a short, familiar tablet and you can plan the hour, sildenafil is not a failed drug. If clock-watching wrecks the night, the tadalafil rows are the ones I walk through. See the sildenafil medicine note if that is the comparison you actually need.
Do the daily-dose studies work as well as the 20 mg night?
They work as a different exposure. Daily 2.5 or 5 mg builds a trough. A 20 mg PRN night is a peak. Both beat placebo on IIEF in their own packs. Neither schedule relaxes the nitrate rule. Choose on frequency and spontaneity, then titrate. I do not call daily 'weaker therapy.' I call it a lower peak with fewer timing arguments. The ledger page is the rest of that talk.
If I get chest pain after a 20 mg tablet, do I use my old spray at hour 40?
No. You go to emergency care and you say tadalafil and the hour you swallowed it. The labeled path, if a nitrate is truly required for a life-threatening situation, is at least 48 hours after the last dose and then only with monitoring. Hour 40 is still inside the hold. A home spray after a Friday almond is how this class earns its worst stories. I will not soften that for a mailbag.
General education from a clinician, not personal medical advice. Bring your own history to your own prescriber.
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