Avanafil

Why there is no syringe

There is no syringe. Avanafil is an oral film-coated tablet in strengths of 50 / 100 / 200 mg, swallowed whole, and the only "dose conversion" it involves is picking the right tablet. Naming a barrel here would invent an instrument the reader does not have. What does need converting on this drug is time, not volume: the label's lead time (as early as 15 minutes before) and the window after it are the numbers that decide whether a dose works, and /tools/ed-medication-timing does that arithmetic from these same figures.

Administration

1. 1

   Rule out nitrates before anything else

   This is the step that kills people when it is skipped. “Administration of STENDRA with any form of organic nitrates, either regularly and/or intermittently, is contraindicated.” (section 4.1 Nitrates). That covers nitroglycerin tablets, sprays, ointments, pastes and patches, isosorbide mononitrate and dinitrate, and the recreational nitrites sold as “poppers”. Guanylate cyclase stimulators such as riociguat are contraindicated too: “Do not use STENDRA in patients who are using a GC stimulator, such as riociguat or vericiguat. PDE5 inhibitors, including STENDRA may potentiate the hypotensive effects of GC stimulators.” (section 4.3 Concomitant Guanylate Cyclase (GC) Stimulators).

2. 2

   Check the interval before any nitrate is given

   At least 12 hours. “In a patient who has taken STENDRA, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered.” (section 4.1 Nitrates). Two of the four labels name an interval that must elapse before a nitrate can even be considered in a life-threatening situation: 12 hours for avanafil, 48 hours for tadalafil. The sildenafil label says it is unknown, and the vardenafil label says it has not been determined. None of the four says a nitrate is ever safe alongside a dose.

3. 3

   Take it the lead time the label gives

   “The recommended starting dose is 100 mg. STENDRA should be taken orally as needed as early as approximately 15 minutes before sexual activity.” (section 2.1 Erectile Dysfunction). Note what that figure is: dosage section instruction; 50 mg is 30 min, not 15. No label of the four states an “onset of action”, so nothing on this page presents one.

4. 4

   Account for food

   A high-fat meal delays the peak by about 1 hour; the label calls the change clinically minimal. “When STENDRA (200 mg) is taken with a high fat meal, the rate of absorption is reduced, with a mean delay in Tmax of 1.12 to 1.25 hours and a mean reduction in Cmax of 39% (200 mg). There was an approximate 3.8% decrease in AUC. The small changes in avanafil Cmax and AUC are considered of minimal clinical significance; therefore, STENDRA may be administered with or without food.” (section 12.3 Pharmacokinetics).

5. 5

   Check which strength the 15-minute figure belongs to

   The famous 15 minutes is not the figure for every tablet. The label titrates in both directions: “Based on individual efficacy and tolerability, the dose may be increased to 200 mg taken as early as approximately 15 minutes before sexual activity, or decreased to 50 mg taken approximately 30 minutes before sexual activity” (section 2.1). Fifteen minutes applies to 100 mg and 200 mg; 50 mg is a 30-minute lead time.

6. 6

   Sexual stimulation is required

   The dosage section states it outright: “Sexual stimulation is required for a response to treatment” (section 2.1 Erectile Dysfunction).

7. 7

   Do not repeat the dose the same day

   “The maximum recommended dosing frequency is once per day.” (section 2.1 Erectile Dysfunction). The label states no duration of effect. The avanafil label states no duration of effect. The bar shows the terminal half-life instead.

Storage

• —Store at 20–25 °C (68–77 °F); excursions permitted, 15–30 °C (59–86 °F) [see USP Controlled Room Temperature]. Protect from light — quoted from section 16 of the STENDRA label.
• —Keep the tablets in the original container, out of reach of children.
• —Tablets ordered from an unlicensed overseas seller are outside all of this. FDA has repeatedly found products sold as PDE5 inhibitors that contain undeclared active ingredient at undeclared strengths; nothing on this page describes those.

Monitoring

Frequently asked questions

What dose does the FDA label actually state?

The Stendra label's dosage section states: “The recommended starting dose is 100 mg. STENDRA should be taken orally as needed as early as approximately 15 minutes before sexual activity.” It then states: “Based on individual efficacy and tolerability, the dose may be increased to 200 mg taken as early as approximately 15 minutes before sexual activity, or decreased to 50 mg taken approximately 30 minutes before sexual activity.” and “The maximum recommended dosing frequency is once per day.” The approved as-needed range is therefore 50–200 mg, and the tablet strengths supplied are 50 / 100 / 200 mg. The 50 mg dose is taken about 30 minutes before activity, not 15 — the 15-minute lead time applies to 100 mg and 200 mg.

How long before sex should it be taken, and how long does it last?

The label says to take it as early as 15 minutes before, and be clear what that figure is — the basis is dosage section instruction; 50 mg is 30 min, not 15. For duration: The label states no duration of effect. The avanafil label states no duration of effect. The bar shows the terminal half-life instead. “STENDRA has a terminal elimination half-life of approximately 5 hours.” (section 12.3 Pharmacokinetics). None of the four labels states an “onset of action”; they state a lead time or a time-to-peak, which are different quantities.

Can it be taken with nitrates if enough time has passed?

At least 12 hours. The label's own words: “In a patient who has taken STENDRA, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered.” (section 4.1 Nitrates). All four labels contraindicate concomitant use with organic nitrates or nitric oxide donors in any form — nitroglycerin, isosorbide mononitrate or dinitrate, and amyl or butyl nitrite "poppers". A PDE5 inhibitor taken with a nitrate can drop blood pressure to a dangerous level. Guanylate cyclase stimulators such as riociguat are contraindicated on all four labels as well. Where a label declines to name a safe interval, that is not the same as saying none is needed — it is the label saying the answer is not known, and this page does not fill it in.

What if I am already on an alpha-blocker for my prostate?

Start at 50 mg; be stable on the alpha-blocker first. The label states: “If STENDRA is co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating treatment with STENDRA, and STENDRA should be initiated at the 50 mg dose” (section 2.3 Concomitant Medications). Both drugs lower blood pressure, so the combination is a dose decision for your prescriber, not an adjustment to make on your own.

Is avanafil really the fastest of the four?

On the labels, yes — it is the only one whose dosage section names a lead time in minutes rather than an hour, and 15 minutes is the shortest figure on any US PDE5 label. Its median Tmax is correspondingly early: “STENDRA is rapidly absorbed after oral administration, with a median Tmax of 30 to 45 minutes in the fasted state” (section 12.3). But note that the 15 minutes is a dosage-section instruction and the 30 to 45 minutes is a measurement, and neither is an “onset of action” — no label of the four uses that phrase.

How long does avanafil last?

The label does not state a duration of effect. This page prints the terminal half-life instead and says so: “STENDRA has a terminal elimination half-life of approximately 5 hours” (section 12.3). Of the four, only sildenafil and tadalafil labels state how long the effect itself persists.

What does the 12-hour nitrate interval mean?

The STENDRA label states: “In a patient who has taken STENDRA, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 12 hours should elapse after the last dose of STENDRA before nitrate administration is considered.” Twelve hours is the shortest interval named on any of the four labels, and tadalafil's is 48 — a fourfold gap that is a direct consequence of half-life. The sildenafil and vardenafil labels name no interval at all. In every case the concomitant use remains contraindicated, and a nitrate after the interval is still a decision for an emergency clinician under close monitoring.

Does this page tell me which one to take?

No. It quotes one label. Choosing between the four is a clinical decision that turns on what else you take — nitrates and guanylate cyclase stimulators rule all four out absolutely — on your cardiovascular status, on whether you want a tablet for an occasion or one every day, and on cost. The side-by-side comparison of all four labels is at /charts/ed-medication-comparison-chart.

Sources

1. [1]FDA label — STENDRA (avanafil) tablet, Metuchen Pharmaceuticals, LLC (DailyMed SPL fa7d93e3-b69b-4e02-8146-89760cd8e9d6). Dosage, nitrate contraindication, alpha-blocker dosing, pharmacokinetics and storage all quoted from this document. Drugs@FDA: STENDRA is NDA 202276 (Vivus LLC), 50, 100 and 200 mg tablets, all marketed.
2. [2]Drugs@FDA — STENDRA (avanafil) tablets, NDA 202276, Vivus LLC. 50, 100 and 200 mg tablets, all in prescription marketing status
3. [3]Drugs@FDA: FDA-Approved Drugs — the searchable record of every approved application, used to confirm the application number, the approved strengths and the marketing status of each brand named on this page

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