Oral semaglutide half-life, time to peak and level curve

What does the label say about oral semaglutide’s half-life and peak?

Semaglutide tablets, sold as Rybelsus, carry the same molecule as the injection and the same elimination half-life: approximately one week, by the prescribing information Peptrend cites. What changes is the route. The label puts maximum concentration about an hour after the tablet, estimates absolute bioavailability at about 0.4% to 1%, and reports steady-state exposure after 4 to 5 weeks of daily use.

The preset reads a little finer than the label. Its 6.5-day half-life and 1.5-hour peak match a multiple-dose study in healthy subjects that reported a mean terminal half-life of 153 to 161 hours and a median time to peak of 1 to 2 hours; 6.5 days is 156 hours, inside that range. Its 0.8% is the bioavailability a population model of the clinical pharmacology trials estimated for the dosing conditions on the label, which the paper gives as at least 30 minutes of fasting after the tablet and no more than 120 mL of water. Those trials also covered other conditions, and the estimate moved with them.

What does one tablet look like in the model?

A tablet enters the model at 0.8% of its printed milligrams, so the whole curve stays under 1% of the tablet. It rises within hours, peaks at 0.79% of the tablet’s milligrams, and falls at the week-long half-life, leaving 0.72% when the next day’s tablet is due.

Measured against what was absorbed, that peak is 99.3%, the highest of the six presets. A 1.5-hour climb costs almost nothing against a 6.5-day decay. The absorption rate the app solves from 1.5 hours is about 111 per day, close to arriving all at once, and on the single-dose chart the rise is a near-vertical line at the left edge.

What happens when tablets repeat daily?

Daily tablets stack for weeks, because each day clears only about a tenth of the level. The interval is 0.15 half-lives, so the model builds to nearly ten times what one tablet leaves after a day before it settles. Settled, it ripples between 7.9% and 7.1% of one tablet’s milligrams, a daily peak about 11% above the trough.

The half-life sets the climb, and the interval never enters it. Four to five half-lives is 26 to 32.5 days here, close to the label’s 4 to 5 weeks and close to the weekly injection’s 28 to 35 days. A daily tablet and a weekly injection of the same drug reach a plateau on nearly the same clock. What the interval changes is the shape at the top: a ripple for the tablet, a deep weekly sawtooth for the injection. How long a GLP-1 takes to reach steady state works through the same build-up.

Why is the tablet curve the least certain of the six?

Absorption is the soft number. The population model behind 0.8% found within-subject variability in bioavailability of 137%, and put bioavailability higher with a longer fast after the tablet, levelling off near 1.4% at two hours. The label reports the same rise with a longer fast, and lower absorption with 240 mL of water than with 50 mL. One tablet can deliver far more or far less than the next, and the model applies 0.8% to every one of them.

The same study found the variation much smaller at steady state, 33% within-subject variability in steady-state exposure, because daily dosing and a long half-life average many tablets together. The settled ripple on the chart is the model’s version of that averaging.

The current label also lists a second, newer tablet formulation, with an estimated absolute bioavailability of about 1% to 2%. The preset’s 0.8% belongs to the original tablets. The Absorbed stepper accepts any value from 0.1% to 100%, and the app asks before a preset overwrites it.

Both semaglutide presets write the medication name Semaglutide, and each logged dose keeps its own route, so a switch from the pen to the tablet stays one curve. With the tablet preset applied, earlier injections still count whole and each tablet counts at 0.8%.