14 posts

Dose logging

Injections, titration, site rotation, half-life curves and schedules.

1. What should you log with every GLP-1 dose? Nine fieldsNine typed fields: time, medication, milligrams, route, site, vial, taken, pain and colour. What each one lets you answer later, and why there is no notes box.
2. How long until a GLP-1 reaches steady state? Four to five half-livesFour to five half-lives — 28–35 days for semaglutide, 24–30 for retatrutide, 20–25 for tirzepatide. Why weekly doses stack, and what 'in your system' counts.
3. How to chart a titration, and why the scale lags a dose stepPeptrend colours each segment of the weight line by the dose behind it, so a 1.2 to 3.5 mg ladder reads as a four-colour ramp. Why a step takes weeks to land.
4. Injection site rotation: how to keep track without a body mapRotation works when the order is decided in advance. Peptrend saves a site with every dose and suggests the next by round-robin through your list — no body map.
5. When does a GLP-1 peak after injection? Tmax and the absorption curveHours to days after the shot — 1 to 3 days for semaglutide, 8 to 72 hours for tirzepatide by the labels. The peak lands at D × F × 2^(−Tmax ÷ half-life).
6. Does oral semaglutide have the same half-life as the injection?About a week either way. The interval is what differs: a daily tablet ripples by about 10%, while a weekly injection swings by a factor of two.
7. How much is still in your system? A free estimate, explainedPeptrend's In Your System chart is free: a milligram estimate from your logged doses and a published half-life. What it computes, how to read it, where it stops.
8. Oral semaglutide tracker: why a tablet isn't charted as mg takenHow Peptrend logs a daily semaglutide tablet: the Oral route, a 0.8% absorbed share, a 1.5-hour peak, and why the newer 1–2% tablets need a different setting.
9. Orforglipron tracker: how the daily tablet is logged and modelledVersion 1.3.3's orforglipron preset came from phase 1 papers; 1.4.0's comes from the Foundayo label. What each models, and how to set all three yourself.
10. Tracking two medications at once in a GLP-1 dose logSince version 1.5.0 Peptrend logs a main medication and any number of others, each with its own half-life, its own curve and its own next-dose date.
11. Switching from semaglutide to tirzepatide: what the dose log showsAfter a switch, Peptrend draws semaglutide clearing on its own 7-day half-life while tirzepatide builds on 5 days. Two lines, never one total, with the numbers.
12. Missed or late GLP-1 dose? How to log what actually happenedLog a late dose at the time you took it and leave a skipped one out. What that does to Peptrend's next-dose date, its overdue ring and its level estimate.
13. Weekly GLP-1 doses across time zones: the log, curve and reminderFly from Los Angeles to Tokyo and a Sunday-night dose reads as Monday afternoon. What Peptrend's log, level curve, next-dose date and reminder do when you travel.
14. Started logging mid-treatment? Why the level estimate reads lowPeptrend's In Your System estimate counts only logged doses. Start a log in month three and it reads half the full figure for a week. How to backfill.