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Sephira Med Centres

Scan · sildenafil

How long does Viagra last at 4 hours?

Medically reviewed by Dr. Yuki Tanaka, MD - Clinical pharmacology, Toronto

Last reviewed · 3 min read · Updated

Bone review card, cobalt edge, lime chip: clock at four, blue tablet

When visual sexual stimulation began 4 hours after the tablet, 13 of 16 men on sildenafil 100 mg (81%) and 5 of 16 on placebo (31%) were responders. Eardley's duration program enrolled 16 men. Terminal half-life on the US label is about 4 hours. The usual labeled start is still 50 mg, not 100.

What did the 4-hour program count?

Responders were men with a grade 3 or 4 erection, or rigidity over 60 percent, during 60 minutes of visual stimulation that started at the 4-hour mark. Thirteen of 16 on 100 mg met that bar. Five of 16 on placebo did.

Median duration of those grade 3 or 4 erections at 4 hours was 5 minutes on sildenafil (range 0-45) versus 0 minutes on placebo. This scan does not add later-hour n/N from other clocks.

Was the 4-hour program run at the usual start?

Eardley used 100 mg, the labeled maximum, for that duration arm. The US label still starts most adults at 50 mg. A 4-hour date is not a reason to open at 100 mg.

Step-up after a clean 50 mg trial lives on the dose ladder. This room only names the study tablet.

Is the 4-hour swallow the same as the 4-hour stimulation clock?

No. The label's 30-minute to 4-hour line is when to take the tablet. Eardley's program started stimulation 4 hours after a single 100 mg dose. Those are two different clocks.

Hour placement for the swallow sits on the hour scan. Do not treat a 30-minute swallow as this 16-man duration read.

What does a 4-hour half-life add to that night?

Terminal half-life of sildenafil is about 4 hours on the US Viagra label. Plasma is already falling when the 4-hour stimulation clock starts. The 16-man program still found 13 of 16 responders there.

Half-life is not a promise that every 50 mg night lasts four hours. It is the labeled terminal number next to a 100 mg duration read.

Can a second tablet stretch the 4-hour mark?

Once per day is the maximum frequency. The 16-man program used one 100 mg dose. A second swallow the same calendar day is not how that clock was measured.

If the first swallow sat under a high-fat plate, the fix is sequence, not a second peak. See meal-tag ratings.

Does a 4-hour plan change the labeled start?

No. Most adults still start at 50 mg. Eardley's duration arm does not rewrite Dosage and Administration. The start scan keeps 50 as the usual first tablet.

Duration context for 25-100 mg sits on the sildenafil panel. This scan stays on the 4-hour responder count.

Sources

  1. DailyMed VIAGRA (sildenafil citrate) tablets, setid c8d046c9-d9e9-4660-8ff1-a6c23b16eb3f
  2. Eardley I, Ellis P, Boolell M, Wulff M. Onset and duration of action of sildenafil for the treatment of erectile dysfunction. Br J Clin Pharmacol. 2002;53 Suppl 1:61S-65S

Checked against the current label and reviewed by Dr. Yuki Tanaka. See Scan, Tag, Board-check, Post.

Board thread

Answers follow the U.S. Viagra label.

Yolanda P., Kansas City Can I use an 8-hour story from a forum as the next clock?

Board reply

This scan stays on the 4-hour program: 13 of 16 versus 5 of 16. It does not add later-hour n/N. Terminal half-life is about 4 hours. A forum 8-hour count is not this file.

Ingrid F., Milwaukee If 13 of 16 worked at 4 hours, should I start at 100 mg?

Board reply

Eardley used 100 mg for that duration program. The labeled usual start is 50 mg. A long evening is not a 100 mg first tablet. Climb only after clean 50 mg trials on the ladder.

Rafael C., Miami We started stimulation at 4 hours and nothing happened on 50 mg. Same study?

Board reply

The 13 of 16 count was on 100 mg in 16 men. Your 50 mg night is not that row. Check the plate, the cue, and the swallow time on the hour scan before you change rungs.