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Zephyra Glass Lab

Duet · PDE5 duet

After food, three PDE5 starts sit on one sheet

Medically reviewed by Dr. Mira Okonkwo, MD - Clinical pharmacology, Edinburgh

Last reviewed · 12 min read · Updated

This sheet puts three oral PDE5 starts on one counter: Cialis 10 mg as needed, Viagra 50 mg, and Levitra 2.5 mg as the small-start / CYP film. The usual vardenafil start on a clean chart is still 10 mg. The lock prints 2.5 mg so the CYP table is not lost.

Capture is SmPC and DailyMed food and posology. Layer maps brands to INNs. Peer-blur deletes checkout copy. Publish is 21 August 2026. Zephyra does not fill a bag.

Frame card

Locked startsTadalafil 10 mg PRN / sildenafil 50 mg / vardenafil 2.5 mg
Shared targetPDE5 in corpus cavernosum smooth muscle
Hard stopOrganic nitrates, nitrites, riociguat
Food splitSildenafil and vardenafil lose peak after fat; tadalafil does not

Three labelled starts, one nitrate rule

Use this sheet when a couple asks which oral PDE5 fits a dinner, a weekend, or a ritonavir chart.

Every oral PDE5 story starts the same way. Cyclic GMP lasts longer after nitric oxide release. Smooth muscle relaxes. Blood enters the corpora. Arousal is still required. After that sentence the clocks diverge, and Dosage searches pretend they do not.

Tadalafil's as-needed start is 10 mg, with or without food, once per day. Sildenafil's start is 50 mg, about one hour before activity, with a high-fat delay. Vardenafil's smallest film is 2.5 mg - the labelled cap with ritonavir, cobicistat, and several other strong CYP3A4 inhibitors - while most clean charts still start at 10 mg.

Cialis, Viagra, and Levitra appear when the foil shows them. The BNF indexes the INN. Full depth lives on the tadalafil frame, the sildenafil frame, and the vardenafil frame. This duet is the wide lens.

Scottish men often arrive with a friend's brand loyalty. Potency is not the differentiator. Timing, meals, the nitrate wall, and whether a CYP or QT caution forces the small vardenafil film are.

Duet at a glance

ClassOral PDE5 inhibitors
Shared ED claimAll three, arousal required
Tadalafil extrasDaily 2.5-5 mg ED; 5 mg BPH
Universal stopNitrates - no milligram loophole

No invented duet dollar

This layer will not invent a side-by-side cash figure for 'a PDE5'. Each member's sourced US row sits on its own frame. The ledger below only points at official pharmacy pages and repeats that Zephyra does not dispense.

Price the INN that is actually on the prescription. A Cialis 10 mg x 30 quote is not a Viagra 50 mg x 10 quote and not a Levitra 2.5 mg x 30 quote. GoodRx stays in those captions, not as a store name in a duet table.

Cialis 10, Viagra 50, and Levitra 2.5 on a duet card
The Zephyra PDE5 duet is literacy only, 21 August 2026. This layer will not invent a side-by-side dollar. Each member's cash sits on its own frame. Official pharmacy links only. Zephyra does not dispense.
PharmacyStrength / countFrame noteOfficial page
WalgreensAsk one INNNot a class coupon and not a combo stripWalgreens desk
PublixAsk one INNNitrate hold sits on every memberPublix desk
WegmansAsk one INNCash lives on the tadalafil, sildenafil, or vardenafil frameWegmans desk
SafewayAsk one INNNo invented duet dollarSafeway desk

Seventeen and a half hours versus a four-hour tail

Tadalafil's mean terminal half-life is 17.5 hours. Clearance is 2.5 L/h. As-needed dosing improved erectile function versus placebo out to 36 hours. That is the weekend question. It is also why a nitrate conversation lasts into the next day.

Sildenafil's terminal half-life is about 4 hours. Fasting Tmax median is 60 minutes (range 30-120). The usable window is the same evening. A second sildenafil at 2 a.m. is already a once-daily breach.

Vardenafil's half-life is about 4-5 hours on a clean chart, clearance about 56 L/h. Fasting Tmax median is about 60 minutes. On ritonavir the half-life stretches to about 26 hours - which is why the 2.5 mg / 72 hour cap exists, not because 2.5 mg is 'slow'.

Daily tadalafil 2.5-5 mg is the only licensed daily-ED board on this sheet. Sildenafil and vardenafil are as-needed drugs in ordinary ED use. Do not invent a daily Viagra habit from a PAH schedule, and do not invent a daily Levitra habit from a leftover 2.5 mg bottle.

ADME on this frame
AbsorptionTadalafil ignores food; sildenafil and vardenafil lose peak after fat.
DistributionAll three reach penile tissue after a systemic oral dose; highly protein bound.
MetabolismCYP3A4 dominates each; vardenafil plus ritonavir is the loudest AUC jump on this sheet.
ExcretionTadalafil t1/2 17.5 h; sildenafil ~4 h; vardenafil 4-5 h (~26 h on ritonavir).

One wall, three half-lives

Organic nitrates, isosorbide, GTN spray, and recreational nitrite poppers are contraindicated with every drug on this sheet. Riociguat sits in the same ban. The interaction is pharmacodynamic. You are holding cGMP up while nitrates flood the system with more of it. That can drop blood pressure hard. There is no 2.5 mg loophole and no 10 mg loophole.

The half-life changes how long the conversation lasts, not whether the ban exists. Tadalafil's 17.5-hour clock is the longest hangover. Sildenafil and vardenafil clear faster on a clean chart. None of that is a DIY 'safe hour' you pick from a forum after chest pain starts.

Edinburgh chest-pain pathways still see men who took GTN at work and a PDE5 the same evening because nobody linked the two bags. A quiet month since the last spray does not reopen the class if angina therapy is still prescribed.

Shared stops before anyone picks a clock
PartnerRiskDesk action
GTN / isosorbide / poppersSevere hypotensionContraindicated - all three INNs
RiociguatAdditive cGMP effectContraindicated
RitonavirHuge vardenafil AUC; tadalafil and sildenafil caps tooUse the labelled film and interval
Doxazosin / tamsulosinOrthostasisStable alpha-blocker first; low PDE5 start

Headache is class noise; back pain and blue tint are not interchangeable

Headache, flushing, dyspepsia, and nasal congestion travel with the class. They scale with dose and vasodilation. One hundred milligrams of sildenafil produces more facial heat than 5 mg daily tadalafil even though both hit PDE5.

Back pain and myalgia show up more in tadalafil trials, often 12 to 24 hours after the dose, usually gone within 48 hours. That is a Sunday-morning story after a Friday 10 mg, not a sildenafil story.

Blue tint and light sensitivity cluster with higher sildenafil doses via PDE6. Vardenafil's distinctive extra is the QT paragraph and the CYP-stretched half-life. Priapism past four hours, sudden vision or hearing loss, and NAION talk are class-wide stop rules.

When this sheet stops being a compare

  • Chest pain, syncope, or sudden vision loss: 999 in Scotland
  • Erection beyond four hours: emergency care, not another tablet tomorrow
  • Alcohol adds orthostasis on all three - tadalafil's food forgiveness is not drink forgiveness

IIEF bands look alike; the logistics do not

Registration trials for all three used IIEF erectile-function domain change and successful intercourse attempts. In general ED populations the improvement bands sit in the same neighbourhood. Where they diverge is who stays on therapy when dinner is late, when a second evening appears, or when a protease inhibitor is already on the chart.

Head-to-head studies exist and are smaller than marketing implied. When a patient demands the strongest tablet, the better question is long coverage, a fasted 50 mg peak, or a CYP-legal 2.5 mg vardenafil film. It is not which logo won a crossover.

Tadalafil's extra claims - daily ED and 5 mg BPH - do not make it stronger in a single night. Sildenafil's first-in-class fame does not cancel the food paragraph. Vardenafil's fast Tmax does not cancel the QT study or the 49-fold ritonavir AUC.

Dates that still govern the three starts

1998

Sildenafil approved for ED; 50 mg becomes the public start.

2003

Tadalafil and vardenafil join; 10 mg Cialis PRN and 2.5-20 mg Levitra films land.

2008+

Daily tadalafil and the BPH 5 mg claim expand the calendar fork.

2026-08-21

This duet locks 10 / 50 / 2.5 and refuses a class dollar.

Calendar, plate, or CYP chart - pick the fork that is real

Unpredictable evenings and heavy plates: tadalafil 10 mg as needed, or daily 2.5-5 mg if a floor is the point. Food will not steal the peak. Five units of alcohol still can. See the weekend glass glint and the daily layer.

One known evening and a willingness to eat light: sildenafil 50 mg, fasted or after a light plate, about an hour before. If that pair fails twice, read the dose frame before 100 mg. If the plate will never be light, do not keep blaming 50 mg.

A chart that already holds ritonavir, cobicistat, or another listed strong 3A4 inhibitor: vardenafil may be the 2.5 mg film on a long interval, or it may be the wrong INN. Tadalafil as-needed then caps at 10 mg every 72 hours (daily 2.5 mg). Sildenafil often starts at 25 mg. None of those are 'take your mate's 20 mg'.

Congenital long QT or class IA/III anti-arrhythmics: vardenafil is the labelled avoid. That is the QT glint in one sentence. The other two INNs still need a nitrate and CYP check. They do not inherit vardenafil's thorough-QT paragraph.

Dinner is what actually splits the class

Tadalafil absorption does not change with food. Rate and extent stay put. A Leith curry does not blunt a 10 mg Cialis peak the way it blunts a 50 mg Viagra peak.

Sildenafil after a high-fat meal: mean Tmax delays about 60 minutes, mean Cmax falls about 29%. The UK SmPC says onset may be delayed versus fasting. That is the restaurant paragraph on the meal glint.

Vardenafil after a high-fat meal: Cmax fell 18% to 50% in two food-effect studies. The UK SmPC allows the tablet with or without food and warns that onset may be delayed. Absolute bioavailability is only about 15% even fasting, so a fat cut lands on a thin peak.

If the couple's real complaint is 'the tablet failed after steak', the first fork is not a stronger milligram. It is whether they are on the food-sensitive pair or on tadalafil. Jumping sildenafil from 50 mg to 100 mg after one fed evening is how flushing gets louder without fixing the clock.

Food fork this duet will not flatten
After a high-fat plateTadalafil 10 mgSildenafil 50 mgVardenafil 2.5 / 10 mg
Absorption / peakUnchangedTmax +60 min; Cmax ~-29%Cmax -18% to -50%
Label food lineWith or without foodWith or without; onset may delayWith or without; onset may delay
Practical eveningDinner can stayFast or eat lightFast or eat light

What 10, 50, and 2.5 actually mean on the labels

Cialis 10 mg as needed is the recommended start before anticipated activity. Step to 20 mg or down to 5 mg. Once per day. The 10 mg and 20 mg films are not recommended as a continuous daily habit. Daily ED is 2.5 mg, which may rise to 5 mg. Five milligrams daily also carries BPH.

Viagra 50 mg as needed is the recommended start about one hour before (30 minutes to four hours on the US label). Step to 100 mg or down to 25 mg. Once per day. Twenty-five milligrams is also the consideration when age >65, CrCl <30, cirrhosis, or a strong CYP3A4 inhibitor already raise exposure.

Levitra 2.5 mg is the smallest film and the CYP / stacked-caution cap. Ritonavir or cobicistat: 2.5 mg in 72 hours. Several other strong inhibitors: 2.5 mg in 24 hours. Stable alpha-blocker plus those inhibitors: 2.5 mg start. For most men without those cuts, the start is still 10 mg, with 5 mg as the usual step down and 20 mg as the ceiling.

A compare that crowns 20 mg tadalafil, 100 mg sildenafil, and 20 mg vardenafil as 'the real doses' is copying weekend searches. A compare that pretends 2.5 mg vardenafil is the usual first swallow for a healthy man is copying the lock without the CYP table. This sheet prints both facts.

Three numbers this duet refuses to mash
Lock on this siteLabelled jobCommon mix-up
Tadalafil 10 mg PRNAs-needed Cialis startTreating it as daily 2.5 mg
Sildenafil 50 mgAs-needed Viagra startJumping to 100 mg after one dinner
Vardenafil 2.5 mgSmall start / CYP capCalling it the usual first swallow

Bring the sheet to the GP, not a trophy to the chemist

After food, tadalafil 10 mg keeps its peak, sildenafil 50 mg often does not, and vardenafil's thin bioavailability loses more Cmax. The locked small vardenafil film is 2.5 mg when the CYP table says so. Nitrates ban the class. Confirm the milligram with the clinician who has the chart.

Editorial mail: [email protected]. Emergency: 999. Dr. Mira Okonkwo, lens page, 21 August 2026.

Sources

  1. Cialis 10 mg SmPC (emc) and DailyMed CIALIS - 10 mg as-needed start, food-free absorption, t1/2 17.5 h.
  2. Viagra 50 mg SmPC (emc) and DailyMed VIAGRA - 50 mg start, Tmax +60 min and Cmax -29% with food.
  3. Levitra / vardenafil DailyMed and EPAR - 2.5 mg CYP caps, 10 mg usual start, high-fat Cmax 18-50%, QT study.
  4. BNF PDE5 chapter - shared nitrate wall. Living Dosage SERP pages (Drugs.com, Healthline, Mayo) for question shape only.

Checked against the current label and reviewed by Dr. Mira Okonkwo. See Capture → Layer → Peer-blur → Publish.

Glint thread

Dr. Mira Okonkwo keeps PDE5 duet threads on the three locked starts: tadalafil 10 mg as needed, sildenafil 50 mg, vardenafil 2.5 mg as the small film. Educational only. Your GP writes the dose. Scotland emergency: 999. [email protected] is for citations.

Dougie, Leith GP offered tadalafil or sildenafil. Is the long half-life actually worth a different NHS repeat?

Desk reply

Half-life is logistics, not magic strength. Tadalafil 10 mg as needed can still be in play the next evening - the label's as-needed window versus placebo runs out to 36 hours. Sildenafil 50 mg is a same-evening tablet with a four-hour tail and a food delay. NHS pricing follows generic availability and pack size, not which logo won a bedroom trial. If nights are spontaneous and dinners are heavy, the tadalafil frame is the compare. If you can eat light and want one known hour, stay on the sildenafil frame. I will not pick the repeat by email.

Nairn, Newhaven Can we split tablets across the three drugs to save money?

Desk reply

Only when the pharmacist says that specific film is scored and stable as a half. Many ED generics are not. Tadalafil 20 mg to 10 mg is a common clinic workaround when the prescription allows it. Film-coated sildenafil 100 mg halves often crumble. A 2.5 mg vardenafil tablet is already the small film; splitting it is how you invent a dose the label never studied. Cost saving does not open a second swallow the same day and does not bypass a CYP interval. Ask the chemist for the labelled strength of the INN on the script. A 2.5 mg vardenafil half is not a studied dose.

Maisie, Morningside Chemist mentioned Levitra 2.5 mg. Is that weaker than Viagra 50 mg?

Desk reply

It is a different job. Fifty milligrams is the usual sildenafil start. Two-point-five milligrams of vardenafil is the small film and the CYP cap - ritonavir or cobicistat, 2.5 mg in 72 hours; several other strong inhibitors, 2.5 mg in 24 hours. On a clean chart vardenafil still starts at 10 mg. Weaker is the wrong word if a 49-fold AUC rise is why the 2.5 mg foil is in the bag. Open the vardenafil frame and the QT glint before you treat 2.5 mg as a timid GP.

Elspeth, Corstorphine 100 mg sildenafil after a weak 50 mg made him flushed all night. Switch class or push on?

Desk reply

Ask whether the 50 mg was fasted. If it followed a heavy dinner, 100 mg bought a higher peak and the same food problem. Two fasted 50 mg evenings belong in the diary before anyone abandons the INN or lives at the ceiling. If side effects dominate on a true fasted 50 mg, 25 mg or a switch to tadalafil 10 mg as needed is a cleaner fork than another 100 mg. Log sitting blood pressure if the GP asked. Chest pain, vision change, or an erection beyond four hours stops the trial.

Struan, Portobello We eat late. Which locked start survives a Friday curry?

Desk reply

Tadalafil 10 mg. Food does not change its absorption. Sildenafil 50 mg after a high-fat plate loses about an hour of Tmax and about 29% of Cmax. Vardenafil can lose 18% to 50% of Cmax after a high-fat meal, and its fasting bioavailability is only about 15% to begin with. If the curry is non-negotiable and you keep insisting on sildenafil, you are arguing with the SmPC. Read the meal glint before anyone writes 100 mg to 'beat dinner'.

Innes, Canonmills He has a long-QT note from years ago. Can we still use the 50 mg or 10 mg starts and skip Levitra?

Desk reply

Vardenafil is the labelled avoid when congenital long QT or class IA/III anti-arrhythmics sit on the chart. Skipping Levitra does not automatically green-light sildenafil 50 mg or tadalafil 10 mg. Those two still need a nitrate check and a CYP check. They do not inherit vardenafil's thorough-QT paragraph, and they also do not get a free pass from cardiology. Bring the old letter and the current drug list to the GP. I will not pick a substitute INN from a glint thread. Sudden syncope with palpitations after any of these tablets is 999.

Padraig, Gorgie He is on tamsulosin. Which of the three locked starts is least messy?

Desk reply

None of them is 'add tonight'. Alpha-blockers plus any PDE5 can drop standing pressure. Tadalafil 5 mg daily is a labelled BPH and ED-plus-BPH dose, which is a different visit from a 10 mg Friday film on top of tamsulosin. Vardenafil on a stable alpha-blocker starts at 5 mg, or 2.5 mg if a listed CYP inhibitor is also present. Sildenafil starts low when hypotensive partners already sit on the chart. Stabilise the alpha-blocker first. Watch standing pressure. Do not stack two prostate vasodilators as a home experiment. Solo tadalafil for BPH is not the same sentence as two active hypotensives the same morning.

Fenella, Stockbridge He keeps GTN at work unused for weeks. Is any of the three starts safe?

Desk reply

No. Organic nitrates and all three PDE5 inhibitors are contraindicated together. That includes GTN spray, isosorbide, and poppers. A quiet stretch since the last spray does not reopen the class if angina therapy is still prescribed. Two-point-five milligrams of vardenafil is not a loophole. He needs a cardiology-aware conversation about ED options that are not PDE5, or a formal review of the anti-anginal plan. Chest pain during or after any vasodilator is 999 in Scotland.

Sorcha, Bruntsfield The duet feels like too many numbers. Where do we start reading?

Desk reply

Start here for orientation. Then open one glint that matches the actual sticking point - meals, weekend calendar, or QT - and the frame for the INN the GP named. Bring a one-line diary: dose time, meal size, side effects, intercourse yes or no. Zephyra does not prescribe or sell tablets. Mail [email protected] if a cite is wrong. Medical emergency in Scotland remains 999. The lens page is not a clinic slot. Price each INN on its own frame. This duet will not invent a class dollar.