Why does everyone still say weekend pill if Lilly never printed it?
How a 5 mg daily Cialis card gets priced
A nickname is not a price. The desk that matters is the one that turned a 17.5-hour half-life into two labeled cards a man can actually fill.
Patients and French papers coined 'Le Weekend' after a 36-hour response window, not after a marketing brief. That window is a pharmacokinetic leftover: roughly a quarter of a 20 mg dose is still on board at 36 hours. The US label never sold a weekend. It sold as-needed 5, 10, and 20 mg after November 2003, then a once-daily 2.5 and 5 mg lane in January 2008. The SERP lock on this site is the pair that still gets asked for: 5 mg daily or a 20 mg PRN card.
Pricing follows the card, not the rumor. A 20 mg tablet taken on a Friday can cover a quiet weekend without a second swallow. A 5 mg daily strip covers a busy week without a clock. Generic tadalafil after the 2018 US patent lapse collapsed the old brand premium, so the choice is no longer 'can I afford daily.' It is which calendar you actually live. The molecule file sits in the tadalafil reference. Do not invent a dollar figure from a screenshot. Ask the pharmacy that will fill the script.
Bothell, not Indianapolis: IC351 on a small bench
ICOS Corporation sat in Bothell, Washington, a 1989 biotech chasing cell-signalling enzymes, not a men's-health franchise. Phosphodiesterases were one family on that bench. Catalog IC351 blocked phosphodiesterase type 5 with a selectivity the chemists liked, and it lingered. That linger is the whole later business.
Glaxo Wellcome had an earlier partnership with ICOS from 1991. It lapsed in 1996 when the pipeline did not match Glaxo's core markets. ICOS kept the compound. Phase 1 work on IC351 started in 1995. Phase 2 in men with erectile dysfunction opened in 1997, after Pfizer's 1998 sildenafil launch had already proved the enzyme was a real target. A second entrant had to be different. Duration was the difference they already had.
Glaxo walked. Lilly stayed.
A small bench can find a molecule. It cannot run global phase 3, write a worldwide label, and staff a sales force. That is the joint-venture ping.
Eli Lilly and ICOS formed Lilly ICOS LLC in 1998. ICOS brought IC351 and the early science. Lilly brought trial scale, regulatory muscle, and a global desk. The generic name tadalafil and the brand Cialis were filed with the NDA around 2000-2001. The FDA asked for more confirmatory pharmacology and manufacturing work; the companies sent the extra package in 2003.
Europe cleared tadalafil in late 2002. The US nod landed on 21 November 2003, the third oral PDE5 inhibitor after sildenafil and vardenafil. Paul Clark, then ICOS chief, called it the first chapter of a research shop becoming a product shop. Lilly bought ICOS outright in 2007 for about $2.3 billion and folded the franchise in-house. The name on the bottle is Lilly's. The discovery address is still Bothell.
Half-life 17.5 hours is the whole price tag
Absorption
Oral. Median Tmax about 2 hours (range 0.5-6). No clinically meaningful food effect. Bioavailability after first pass is high relative to the shorter cousins.
Distribution
Volume of distribution about 63 L. Protein binding about 94 percent.
Metabolism
CYP3A4 to a catechol metabolite. Ketoconazole 400 mg daily raised a 20 mg AUC by 312 percent. Rifampin 600 mg cut a 10 mg AUC by 88 percent.
Excretion
Feces about 61 percent, urine about 36 percent, mostly as metabolites. Not dialyzable in a useful way.
Terminal half-life is about 17.5 hours in healthy men and about 21.6 hours in older men. Sildenafil and vardenafil sit near 4 hours. That gap is not a potency story. It is a clock story. Porst and colleagues showed a usable response out to 36 hours. Brock's 2002 integrated analysis of five randomized trials is what the 20 mg weekend card actually stands on, not a slogan.
Median time to peak is about 2 hours. Some men report an effect by 30 minutes. Counseling a 15-minute onset as reliable is a miss - fewer than 40 percent of attempts succeed that early. Food does not blunt tadalafil the way a fatty meal blunts sildenafil. Take the 20 mg card with dinner or without. The enzyme block still needs sexual stimulation. A long half-life is not a constant erection. It is a longer interval in which a real signal can land.
November 2003: the 20 mg weekend card
The first US label started most men at 10 mg as needed, with 20 mg if 10 mg was thin and 5 mg if metabolism or other drugs required a cut. Not more than once a day. The 20 mg tablet is the card this desk still posts for a weekend, because that is the strength men ask for when they want one swallow and a long window. The 10 mg start is still the labeled default for a first as-needed try.
One hold was locked on day one and has never loosened. Any organic nitrate - tablets, sprays, patches, long-acting pills, or recreational nitrites - is an absolute contraindication. Both drugs drive the same downstream relaxation. Stack them and blood pressure can fall to a dangerous, sometimes fatal level. After a tadalafil dose the label wants at least 48 hours before emergency nitrate is even considered, and then only under close monitoring. That hold is longer than the short-acting cousins because the half-life is longer. Tell every clinician you take it. The regulator's own language is on the FDA site and the current tablet file is on DailyMed for Cialis.
January 2008: the 5 mg daily strip
A long half-life does a second job once you stop thinking in events. It holds a low steady level if you swallow a small tablet every morning.
On 8 January 2008 the FDA cleared Cialis 2.5 mg and 5 mg for once-daily use in erectile dysfunction. Three phase 3 randomized, double-blind, placebo-controlled studies backed that lane. Men took the tablet without tying it to a planned encounter. The 5 mg daily strip is the SERP twin of the 20 mg weekend card on this site. Start daily at 2.5 mg if you need a gentler climb; 5 mg is the usual working daily dose when the gut and the head tolerate it.
Lilly's own note at the time said daily use may fit men who expect sex about twice a week or more. That is still a fair calendar split. Daily is not stronger. It is present. The trial read and the IIEF points live in the Cialis trial-signal post. The calendar choice itself is the daily-versus-PRN split.
Same molecule, two later desks: BPH and Adcirca
1989
ICOS founded in Bothell, Washington, working cell-signalling enzymes including phosphodiesterases.
1991-1996
Glaxo Wellcome partnership; it lapses. ICOS keeps IC351.
1995-1997
Phase 1, then phase 2 in men with ED.
1998
Lilly ICOS LLC formed to develop and market the compound.
21 Nov 2003
FDA approves Cialis for ED as needed (5, 10, 20 mg). Europe had cleared it in 2002.
2007
Lilly buys ICOS for about $2.3 billion.
8 Jan 2008
Once-daily 2.5 mg and 5 mg cleared for ED.
May 2009
Adcirca 40 mg daily cleared for PAH after PHIRST.
Oct 2011
Daily 5 mg added for BPH and for ED plus BPH.
PDE5 also sits in prostate and bladder-neck smooth muscle. Blocking it eases lower-urinary symptoms of benign prostatic hyperplasia. In October 2011 the FDA added once-daily 5 mg for BPH signs and for men who carry both BPH and ED. Only the 5 mg daily dose holds those two extra indications. A 20 mg PRN card will not treat the night-time trips. That is a steady-level job.
The same enzyme sets tone in pulmonary arteries. In May 2009 tadalafil 40 mg once daily - two 20 mg tablets, branded Adcirca - was cleared for pulmonary arterial hypertension after PHIRST-1 showed a 33-meter gain in six-minute walk against placebo. United Therapeutics licensed the US PAH desk from Lilly in late 2008. Different brand, different dose, different specialists. Do not borrow an Adcirca bottle for a weekend card, and do not treat a lung-pressure clinic as a Cialis refill.
Where a 20 mg weekend Cialis fill is actually posted
A fill is a licensed US pharmacy, not a banner. This desk does not stock a cart. If you want a 20 mg PRN card or a 5 mg daily strip, the script goes to a pharmacy your clinician can name - a chain counter, an independent, or a mail-order bench that already holds your other medicines. GoodRx and similar coupon desks can show a cash range. They are not the store. The href on a row should be that chain's own pharmacy page, not a coupon domain pasted onto someone else's name.
Sildenafil and vardenafil are shorter clocks, not cheaper substitutes you swap without a new look at nitrates, alpha-blockers, and CYP3A4 inhibitors. Those two files sit at sildenafil and vardenafil. Tadalafil's food-independence and daily lane are the Bothell properties that still price the card. A patient-level walk-through of class warnings is on MedlinePlus.
What the Bothell file still flags
CYP3A4 inhibitors raise exposure. On a PRN card the labeled ceiling with a potent inhibitor such as ketoconazole or ritonavir is 10 mg, not more than once every 72 hours. On a daily strip the ceiling is 2.5 mg. Inducers such as rifampin can hollow out a daily 5 mg until it looks like a missed dose. Severe hepatic impairment and creatinine clearance under 30 mL/min are poor ground for the daily lane.
Alpha-blockers need a stable dose and a caution, not a second hypotensive stacked on top to treat BPH. Tadalafil 5 mg daily is approved as monotherapy for BPH symptoms. Combining it with an alpha-blocker as a dual BPH plan is the miss the label warns about. Back pain and myalgia often land 12 to 24 hours after a dose and fade within 48 hours. That delayed ache is a tadalafil signature, not a kidney stone until proven otherwise.
Post: one property, two priced cards
Bothell did not invent a stronger PDE5 blocker. It priced a longer one. The 20 mg weekend card and the 5 mg daily strip are the same half-life aimed at two calendars. Lilly scaled it. The later BPH and PAH desks are the same enzyme in other rooms. The slogan is optional. The 48-hour nitrate hold is not.
If you came for a story about a weekend, leave with a file: IC351, 17.5 hours, 21 November 2003, 8 January 2008, then 2011 for the prostate. Change a dose or a schedule only after your own clinician has the full list. The disclaimer on this site is the legal line. Elena's thread below is the human one.
Reader mail
Reader questions on this article
Answered by Dr. Elena Vasquez, MD · Urology & men's health
Readers pinged the Bothell file after this post. These are the traces worth answering in full.
Because patients and the French press named the window before the company could trademark it. Tadalafil's half-life is about 17.5 hours, so a 20 mg as-needed tablet can still support a response about 36 hours later. That is a real pharmacokinetic leftover, not a slogan I would write on a box. It does not mean a 36-hour erection. You still need arousal. What you bought is a longer interval without a second swallow. On this desk the weekend card is the 20 mg PRN tablet. The 5 mg daily strip is the other priced card, and it is a different calendar, not a stronger weekend.
I had never heard of ICOS. How does a shop I cannot name invent Cialis?
More often than people think. ICOS was a Bothell biotech founded in 1989 to work cell-signalling enzymes. IC351 was one PDE5 blocker on that bench. Glaxo Wellcome partnered early and walked in 1996. Lilly formed Lilly ICOS LLC in 1998, ran the big trials, and put Cialis on the US label on 21 November 2003. Lilly then bought ICOS in 2007 for about $2.3 billion. The bottle says Lilly. The discovery address is still Bothell. A great many drugs travel that exact path: small bench, large desk, then the large desk owns the result.
Is a 20 mg weekend card safer or riskier than a short pill?
Neither is safer in kind. The class hold is identical: no organic nitrates, no poppers. The difference is duration. After tadalafil the label wants at least 48 hours before emergency nitrate is even considered, and then only with monitoring. A short-acting cousin clears that hazard faster. So the danger is not a different chemistry. It is a longer window in which a chest-pain team cannot freely give nitroglycerin. I tell every man on a 20 mg card or a 5 mg daily strip to say the drug name out loud in an emergency bay. That sentence matters more than the nickname.
How does one molecule also treat a prostate and a lung disease?
It treats an enzyme, not an organ. PDE5 sits in penile vessels, in prostate and bladder-neck muscle, and in pulmonary arteries. Block it in the penis and you aid an erection. Block it every day at 5 mg and you can ease BPH urinary symptoms - that indication landed in October 2011, and only the daily 5 mg dose holds it. Block it at 40 mg as Adcirca and you can lengthen a six-minute walk in pulmonary arterial hypertension after PHIRST. Same molecule, three tissues, three desks. Do not borrow the lung bottle for a weekend card.
Why a second brand, Adcirca, if it is the same drug?
To keep two jobs from colliding. PAH dosing is 40 mg once daily, usually two 20 mg tablets, under a separate brand that United Therapeutics licensed for the US in 2008. The patients, the specialists, and the monitoring are not a urology refill. A distinct name and pack lower the chance that a weekend Cialis card and a lung-pressure regimen get swapped in a pharmacy or a chart. Same tadalafil. Different indication, different dose, different safety desk. I treat them as two products that happen to share a molecule.
Does dinner wreck Cialis the way I was told it wrecks the blue pill?
No. A fatty meal can slow and blunt sildenafil. Tadalafil has no clinically meaningful food effect on the US label. Swallow a 20 mg PRN card with dinner or on an empty stomach and expect the same absorption story. Combined with the long window, that is why the weekend card is less of a choreographed evening. You are not timing the tablet around the steak. You still need sexual stimulation. Food independence is a real Bothell property. It is not a reason to skip the nitrate history.
If it was third to market and not stronger, why did it sell?
It sold the clock. Sildenafil owned first place. Vardenafil arrived the same season. Tadalafil arrived with a 17.5-hour half-life and a 36-hour window no rival could match in 2003. That priced a 20 mg weekend card. In 2008 the same half-life priced a 5 mg daily strip, a lane the short cousins still cannot hold as a labeled steady state. Follow-on drugs do not need to win every measure. One property aimed at a real frustration - planning sex to a four-hour clock - was enough. The IIEF points later confirmed it worked. The calendar is what people still buy.
Where do I actually fill a 5 mg daily strip without a random site?
Use a counter your own clinician can name. Chain, independent, or the mail-order bench that already fills your other scripts. This site does not sell tablets. Coupon sites can show a cash range after the 2018 generic lapse, but they are not the store, and I will not invent a price. The row should point at that pharmacy's own page, not a coupon domain wearing someone else's name. Bring the full medicine list, especially nitrates, alpha-blockers, and CYP3A4 inhibitors, before anyone prices a 5 mg daily or a 20 mg PRN card.
I take ketoconazole. Does that change which card I can use?
It changes the dose, not the molecule. Tadalafil is a CYP3A4 substrate. Ketoconazole 400 mg daily raised a 20 mg AUC by more than three-fold in the label study. On a PRN card the ceiling with a potent CYP3A4 inhibitor is 10 mg, not more than once every 72 hours. On a daily strip the ceiling is 2.5 mg, not 5 mg. I would not start a 20 mg weekend card on top of ketoconazole or ritonavir. I would also not guess. Send me the exact antifungal dose and we will trace the label before anyone posts a fill.
General education from a clinician, not personal medical advice. Bring your own history to your own prescriber.
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