Tadalafil, sildenafil, vardenafil and avanafil belong to the same PDE5 inhibitor class and share the same core erectile mechanism, but they do not have interchangeable pharmacokinetic profiles. Tadalafil stands out for its 17.5-hour terminal half-life and broad post-dose response window, while sildenafil and vardenafil have shorter approximately 4- to 5-hour profiles and avanafil has the earliest dose-to-sex timing in current U.S. labeling.
Those differences should be interpreted through several separate measures. Label timing before sexual activity is not the same as Tmax, half-life is not an exact duration clock, and high-fat meals affect sildenafil, vardenafil and avanafil differently while having no meaningful effect on tadalafil absorption.
This is a class-level comparison rather than a substitute for the detailed pairwise pages. For deeper molecule-specific analysis, use tadalafil vs sildenafil, tadalafil vs vardenafil and tadalafil vs avanafil.
The four drugs share PDE5 inhibition but differ substantially in timing and persistence. Tadalafil has by far the longest terminal half-life, whereas avanafil has the earliest label-supported pre-sex timing at its 100 mg and 200 mg doses.
Sildenafil and film-coated vardenafil occupy a shorter-duration PK range, with median fasting peak concentrations around one hour. Food effects also help distinguish the drugs, especially when high-fat meals are involved.
The final row links to the dedicated tadalafil pairwise comparisons where each relationship is examined in greater depth.
| Feature | Tadalafil | Sildenafil | Vardenafil | Avanafil |
|---|---|---|---|---|
| Common ED brand reference | CIALIS | VIAGRA | LEVITRA historically associated with vardenafil | STENDRA |
| Median fasting Tmax | ~2 h | ~60 min | ~60 min for film-coated tablet | ~30–45 min |
| Terminal half-life | 17.5 h | ~4 h | ~4–5 h | ~5 h |
| Typical label timing before sexual activity | As-needed counseling: at least ~30 min | Usually ~1 h; permitted 30 min–4 h | Approximately 60 min | 100/200 mg as early as ~15 min; 50 mg ~30 min |
| Late ED-response evidence | Improved erectile function demonstrated up to 36 h | Effect observed up to 4 h in a time-course study, diminished vs 2 h | No analogous tadalafil-style late-hour claim | No analogous tadalafil-style late-hour claim |
| High-fat food effect | No meaningful effect on rate or extent of absorption | Tmax delayed ~60 min; Cmax reduced ~29% | Film-coated tablet Cmax reduced ~18–50% | Tmax delayed ~1.12–1.25 h; Cmax reduced ~39%; AUC reduced ~3.8% |
| Once-daily labeled ED regimen | Yes | No in VIAGRA ED labeling | No | No |
| BPH indication | Yes in CIALIS labeling | No in VIAGRA labeling | No | No |
| Pairwise deep dive | Class comparison hub | Tadalafil vs sildenafil | Tadalafil vs vardenafil | Tadalafil vs avanafil |
Tmax describes when the highest observed plasma concentration occurs, whereas label timing describes when a drug is instructed or supported for use relative to anticipated sexual activity. The two measurements therefore should not be collapsed into a single 'speed' ranking.
Avanafil provides the clearest example: its 100 mg and 200 mg doses may be taken as early as approximately 15 minutes before sexual activity, even though median fasting Tmax is approximately 30 to 45 minutes. Tadalafil can likewise support sexual activity before its approximately 2-hour median Tmax.
Tadalafil-specific interpretation of plasma peak versus clinical response is covered on the tadalafil onset page.
| Drug | Median fasting Tmax | Label-related ED timing |
|---|---|---|
| Tadalafil | ~2 h | At least ~30 min before anticipated sexual activity in PRN counseling |
| Sildenafil | ~60 min | Usually ~1 h; may be taken 30 min–4 h before |
| Vardenafil | ~60 min for film-coated tablet | Approximately 60 min before |
| Avanafil | ~30–45 min | 100/200 mg as early as ~15 min; 50 mg ~30 min |
Tadalafil's mean terminal half-life of 17.5 hours is substantially longer than the approximately 4-hour sildenafil half-life, the 4- to 5-hour vardenafil half-life and the approximately 5-hour avanafil half-life. This produces a much longer tadalafil concentration-time tail after a dose.
That difference helps explain why tadalafil supports a broader planning framework, but half-life should not be used as a direct clinical-duration calculator. A 5-hour half-life does not mean a drug works for exactly five hours, just as tadalafil's 17.5-hour half-life is not synonymous with its 36-hour clinical-response evidence.
The pharmacokinetic meaning of the longer tadalafil profile is examined on the tadalafil half-life page.
| Drug | Terminal half-life | Relative persistence |
|---|---|---|
| Tadalafil | 17.5 h | Longest of these four |
| Sildenafil | ~4 h | Shorter |
| Vardenafil | ~4–5 h | Shorter |
| Avanafil | ~5 h | Shorter |
CIALIS labeling specifically states that as-needed tadalafil improved erectile function compared with placebo up to 36 hours after dosing. VIAGRA has separate time-course pharmacodynamic evidence showing an erectile response for up to 4 hours, although the response at 4 hours was diminished compared with 2 hours.
Current vardenafil and STENDRA labeling do not provide directly comparable tadalafil-style late-hour claims. It would therefore be misleading to manufacture fixed clinical durations for those drugs simply from their 4- to 5-hour terminal half-lives.
For tadalafil, the distinction between persistence and clinical effect is developed further on the tadalafil duration page.
| Drug | Relevant late-response evidence | Half-life can substitute for duration? |
|---|---|---|
| Tadalafil | Improved erectile function demonstrated up to 36 h | No |
| Sildenafil | Effect observed up to 4 h, diminished vs 2 h | No |
| Vardenafil | No directly comparable fixed late-hour claim | No |
| Avanafil | No directly comparable fixed late-hour claim | No |
Tadalafil is the simplest of the four from a meal-PK perspective because food does not meaningfully influence its rate or extent of absorption. The other three can still be taken according to their respective labels, but high-fat meals alter at least part of their absorption profile.
For sildenafil, a high-fat meal delays Tmax by about 60 minutes and lowers Cmax by about 29%. Film-coated vardenafil studies found Cmax reductions of approximately 18% to 50%, while avanafil 200 mg showed a roughly 1.12- to 1.25-hour Tmax delay, a 39% Cmax reduction and only a small AUC reduction.
These are pharmacokinetic differences, not proof that one molecule has greater ED efficacy. Tadalafil's meal evidence is covered on the tadalafil food-effects page.
| Drug | High-fat meal effect |
|---|---|
| Tadalafil | No meaningful effect on rate or extent of absorption |
| Sildenafil | Tmax +~60 min; Cmax −~29% |
| Vardenafil film-coated tablet | Cmax −~18–50% |
| Avanafil 200 mg | Tmax +~1.12–1.25 h; Cmax −~39%; AUC −~3.8% |
Typical ED doses differ widely across these molecules: tadalafil uses a 10 mg starting framework for most as-needed users, sildenafil commonly starts at 50 mg, film-coated vardenafil at 10 mg and avanafil at 100 mg. Those values do not create a potency scale.
Milligrams measure the mass of different molecules with different pharmacokinetics and dose-response relationships. A 100 mg avanafil tablet is not ten times 'weaker' than 10 mg tadalafil, and equal 10 mg tadalafil and vardenafil doses are not pharmacologically interchangeable.
The tadalafil-specific strength and regimen structure remains on the tadalafil dosage page.
| ED product context | Typical starting framework | Other common labeled options |
|---|---|---|
| Tadalafil / CIALIS PRN | 10 mg | 5 mg or 20 mg |
| Sildenafil / VIAGRA | 50 mg | 25 mg or 100 mg |
| Vardenafil film-coated tablet | 10 mg | 5 mg or 20 mg |
| Avanafil / STENDRA | 100 mg | 50 mg or 200 mg |
Among these four ED products, CIALIS uniquely provides both as-needed and once-daily ED treatment frameworks. Its once-daily ED regimen uses lower doses taken at approximately the same time each day without regard to the timing of sexual activity.
CIALIS also carries U.S. indications for BPH and combined ED/BPH. Sildenafil additionally exists in separate PAH product labeling, as does tadalafil, but those pulmonary-hypertension products use different treatment frameworks from their ED counterparts.
Tadalafil's daily strategy and non-ED indications are covered on the daily versus as-needed page, BPH page and PAH page.
| Labeled context | Tadalafil | Sildenafil | Vardenafil | Avanafil |
|---|---|---|---|---|
| As-needed ED | Yes | Yes | Yes | Yes |
| Once-daily ED | Yes | No in VIAGRA labeling | No | No |
| BPH / ED+BPH | Yes in CIALIS labeling | No | No | No |
| Separate U.S. PAH product context | Yes | Yes | No analogous indication | No analogous indication |
All four drugs depend substantially on CYP3A metabolism, so interacting medicines can change exposure across the PDE5 inhibitor class. The exact quantitative effect and label-management rule remain molecule specific and should not be transferred from one drug to another.
Tadalafil's observed metabolites are not expected to be pharmacologically active at measured concentrations. Sildenafil has an active N-desmethyl metabolite, vardenafil's M1 contributes a modest portion of total activity and avanafil's M4 contributes only a small portion of overall pharmacologic activity.
Tadalafil's enzyme-specific evidence is covered separately on the tadalafil CYP3A4 page.
| Drug | Major metabolic route | Metabolite context |
|---|---|---|
| Tadalafil | Predominantly CYP3A4 | Observed metabolites not expected to be pharmacologically active at measured concentrations |
| Sildenafil | CYP3A4 major; CYP2C9 minor | Active N-desmethyl metabolite contributes to pharmacologic effect |
| Vardenafil | Predominantly CYP3A4 with CYP3A5/CYP2C contribution | M1 contributes ~7% of total pharmacologic activity |
| Avanafil | Mainly CYP3A4 with minor CYP2C contribution | M4 contributes ~4%; M16 inactive against PDE5 |
The four molecules have different in-vitro selectivity profiles across phosphodiesterase isoforms. Sildenafil has relatively lower PDE5-versus-PDE6 selectivity, which is consistent with its label-described color-vision effects, while tadalafil, vardenafil and avanafil have their own distinct selectivity patterns.
Selectivity ratios should not be converted into a universal tolerability ranking. In-vitro enzyme preference is only one component of clinical safety, and off-target activity, dose, exposure and observed clinical outcomes all matter.
For example, tadalafil inhibits PDE11 isoforms in vitro, but current labeling does not establish PDE11 inhibition as the proven cause of tadalafil-associated back pain or myalgia.
| Drug | Selected PDE5 vs PDE6 relationship | Interpretive point |
|---|---|---|
| Tadalafil | ~700-fold | Higher PDE5/PDE6 selectivity than sildenafil; PDE11 clinical significance remains undefined |
| Sildenafil | ~10-fold | Lower PDE5/PDE6 selectivity is consistent with transient color-vision effects in labeling |
| Vardenafil | >15-fold | In-vitro selectivity does not define overall tolerability |
| Avanafil | >100-fold | High selectivity does not remove class-level interaction risks |
Class membership does not make every warning or formulation issue identical. Vardenafil has a distinct QT-prolongation warning and avoidance language for congenital QT prolongation and certain Class IA or Class III antiarrhythmics, while sildenafil's label gives particular attention to PDE6-related color-vision effects.
Avanafil has an earlier dose-to-sex framework and current labeling says not to use it with strong CYP3A4 inhibitors. Tadalafil is differentiated by long persistence, once-daily ED treatment, BPH indications and product-specific long-exposure interaction considerations.
These distinctive features are reasons to compare individual labels rather than assuming that all PDE5 inhibitors can be substituted using one class rule.
| Drug | Distinctive label characteristic |
|---|---|
| Tadalafil | 17.5-h half-life, up-to-36-h ED response evidence, once-daily ED and BPH frameworks |
| Sildenafil | Shorter ~4-h profile and prominent PDE6/color-vision context |
| Vardenafil | Specific QT-prolongation warning; current formulations can require formulation-specific interpretation |
| Avanafil | As-early-as-15-min timing at 100/200 mg and strong-CYP3A4-inhibitor prohibition |
A class table is useful for identifying the broad pattern, but it cannot preserve every evidence nuance without becoming repetitive. Each dedicated pairwise page therefore owns the deeper clinical-pharmacology comparison between tadalafil and one alternative.
Use tadalafil vs sildenafil for the broad Cialis-versus-Viagra comparison, including food, duration and active-metabolite differences. Use tadalafil vs vardenafil for vardenafil formulation and QT context, and tadalafil vs avanafil for the early-timing versus long-persistence comparison.
| Detailed comparison | Primary reason to use it |
|---|---|
| Tadalafil vs sildenafil | Flagship pairwise comparison of timing, food, duration, PK and indications |
| Tadalafil vs vardenafil | Shorter PK, vardenafil formulation context and QT-specific warning |
| Tadalafil vs avanafil | Earlier avanafil timing versus tadalafil's broader persistence |
All four molecules demonstrated efficacy for erectile dysfunction within their own clinical development programs, but separate product-label trials are not randomized four-way comparisons. Cross-trial response percentages therefore cannot establish that the highest number belongs to the most effective drug.
What can be compared more reliably are pharmacokinetic and regulatory characteristics: peak timing, half-life, meal effects, labeled administration timing, daily-versus-as-needed frameworks, indications and molecule-specific warnings. Those features describe different profiles rather than one universally superior PDE5 inhibitor.
A longer half-life, earlier labeled timing or higher in-vitro selectivity may matter to a comparison, but none of those attributes alone is equivalent to greater efficacy.
| Comparison method | Appropriate? |
|---|---|
| Compare current-label Tmax and half-life | Yes |
| Compare food-effect data with formulation context | Yes |
| Compare labeled regimen and indications | Yes |
| Rank unrelated clinical-trial response percentages as head-to-head efficacy | No |
| Use half-life alone to name a best drug | No |
| Use in-vitro PDE selectivity alone to name the safest drug | No |
Several common shortcuts mix measurements that answer different questions. Tmax is not clinical onset, half-life is not exact clinical duration and milligram strength cannot be converted directly from one PDE5 inhibitor to another.
It is also inaccurate to say that every shorter-half-life PDE5 inhibitor has the same four- or five-hour clinical duration, or that a high-fat meal makes sildenafil, vardenafil or avanafil unusable. The actual label evidence is more specific and varies by molecule and, in some cases, formulation.
| Misunderstanding | Better interpretation |
|---|---|
| The drug with the earliest Tmax always works fastest | Tmax and clinical response timing are different measures |
| Half-life tells exactly how long an erection response lasts | No |
| Equal milligram doses are equivalent | No |
| High-fat food prohibits sildenafil, vardenafil or avanafil use | No; food changes PK to different degrees |
| Tadalafil's 36-hour window means a 36-hour erection | No |
| One PDE selectivity ratio proves overall safety superiority | No |
Tadalafil, sildenafil, vardenafil and avanafil share the same core PDE5 mechanism but have different pharmacokinetic identities. Tadalafil has the longest half-life at about 17.5 hours, sildenafil and vardenafil have shorter approximately 4- to 5-hour profiles, and avanafil combines an approximately 5-hour half-life with the earliest label-supported pre-sex timing among these four.
Food and regimen structure create additional separation. Tadalafil absorption is not meaningfully affected by food and CIALIS provides both as-needed and once-daily ED frameworks, while high-fat meals alter sildenafil, vardenafil and avanafil absorption to different degrees.
The class also shares major safety principles, especially contraindications involving nitrates and GC stimulators, but molecule-specific warnings and interaction instructions remain important. The pairwise pages should be used when deeper drug-versus-drug detail is needed rather than expanding this hub into three duplicate comparisons.
The major oral ED comparisons are sildenafil, vardenafil and avanafil. All inhibit PDE5 but differ in peak timing, terminal half-life, food effects, labeled administration timing and treatment frameworks.
Among tadalafil, sildenafil, vardenafil and avanafil, tadalafil has the longest terminal half-life at approximately 17.5 hours. Sildenafil is about 4 hours, vardenafil about 4 to 5 hours and avanafil about 5 hours.
Current STENDRA labeling allows avanafil 100 mg and 200 mg to be taken as early as approximately 15 minutes before sexual activity. That label timing should not be confused with its median fasting Tmax of approximately 30 to 45 minutes.
Avanafil has the earliest median fasting Tmax among these four at approximately 30 to 45 minutes. Sildenafil and film-coated vardenafil peak at a median of about 60 minutes, while tadalafil's median Tmax is about 2 hours.
Not necessarily. Tmax measures peak plasma concentration, while clinical onset depends on observed erectile-response data, dose, sexual stimulation and other factors.
Tadalafil has the longest pharmacokinetic persistence and CIALIS has clinical ED-response evidence extending up to 36 hours after as-needed dosing. Half-life and clinical duration are still different measurements.
No. Sildenafil has an approximately 4-hour terminal half-life, and a VIAGRA pharmacodynamic study observed an erectile response up to 4 hours with diminished response compared with 2 hours. The half-life itself is not an exact duration clock.
No. Their approximately 4- to 5-hour terminal half-lives describe elimination, not a guaranteed clinical-response duration.
Tadalafil has the clearest food-independent PK profile in current labeling: food does not meaningfully affect its rate or extent of absorption.
A high-fat meal delays sildenafil Tmax by about 60 minutes and lowers Cmax by approximately 29%.
For film-coated vardenafil tablets, high-fat meal studies reported Cmax reductions of approximately 18% to 50%. Formulation matters because orally disintegrating vardenafil has a different food-effect profile.
With avanafil 200 mg, a high-fat meal delays Tmax by approximately 1.12 to 1.25 hours and lowers Cmax by about 39%, while AUC changes only modestly.
CIALIS has a labeled once-daily tadalafil regimen for erectile dysfunction in addition to as-needed use. The reference ED labels for sildenafil, vardenafil and avanafil use as-needed frameworks.
CIALIS is labeled for the signs and symptoms of BPH and for combined ED/BPH. VIAGRA, vardenafil ED products and STENDRA do not have corresponding BPH indications.
No. Tadalafil, sildenafil, vardenafil and avanafil are different molecules with different dose ranges and pharmacokinetics, so their milligram strengths cannot be converted directly.
Yes. Organic nitrates are contraindicated with tadalafil, sildenafil, vardenafil and avanafil because PDE5 inhibition can potentiate severe hypotension.
Current U.S. labeling contraindicates these PDE5 inhibitors with guanylate cyclase stimulators such as riociguat because of the risk of excessive blood-pressure lowering.
Vardenafil has a shorter 4- to 5-hour pharmacokinetic profile, formulation-specific considerations and a distinct QT-prolongation warning involving congenital QT prolongation and certain Class IA or Class III antiarrhythmics.
Sildenafil has relatively lower in-vitro selectivity for PDE5 over retinal PDE6 than tadalafil, and current VIAGRA labeling connects PDE6 inhibition with transient color-vision abnormalities.
Current labeling does not establish one universal winner. The drugs differ in timing, persistence, meal effects, dosing frameworks, indications and molecule-specific safety characteristics, so the class is better compared by those attributes than by a single best-drug ranking.