How the Dose Club app estimates the amount in your system
The model behind the level chart, the published figures it uses and the reminder that goes with every estimate.
The level chart in the Dose Club app shows an estimate of how much medicine is in your system over time, built from the doses you have logged. It is an estimate from published data, never a measurement, and every screen that shows one carries the same line: "Estimate based on published data. Check with your prescriber before making decisions."
The model
The app uses a one compartment model with first order absorption and elimination. Each logged dose adds a curve that rises as the medicine is absorbed and falls as it is eliminated, and the chart is the sum of every curve. The elimination rate comes from the published half-life. The absorption rate is solved from the published time to peak concentration.
The figures it uses
Each medicine has its own half-life, time to peak and bioavailability, stored with a source and a version so a correction can ship without an app update. Every value is re-checked against the UK Summary of Product Characteristics before launch.
| Medicine | Schedule | Half-life | Peak after a dose | Bioavailability |
|---|---|---|---|---|
| Semaglutide (Wegovy, Ozempic) | Weekly | About 7 days (about 165 hours) | 1 to 3 days | 89% |
| Tirzepatide (Mounjaro) | Weekly | About 5 days | 8 to 72 hours, most within 24 hours | About 80% |
| Retatrutide (investigational) | Weekly | About 6 days (134 to 165 hours in Phase 1) | 12 to 72 hours | Not published |
The half-life, time to peak and bioavailability for semaglutide and tirzepatide are the figures in section 5.2 of each medicine's UK summary of product characteristics. The hours given for the semaglutide half-life, the note that most tirzepatide peaks fall within 24 hours, and the retatrutide row come from published pharmacology work, which the How estimates work page lists. Retatrutide has no UK summary of product characteristics.
For semaglutide and tirzepatide the chart shows an estimated amount in milligrams. For retatrutide, which has no published bioavailability, it shows a percentage of your own peak.
The daily medicines, Wegovy tablets, Foundayo and liraglutide (Saxenda and Nevolat), take their parameters from each UK Summary of Product Characteristics before launch.
What the app does not do
The app never recommends a dose, a dose change or a schedule. Dose Insights describe what happened in each dose period, such as the weight trend and how many days had symptoms, in descriptive wording only. If you miss a dose, the app shows the wording from the patient leaflet for your region and a link to it, and adds nothing of its own.
The "How estimates work" page in the app lists the method and every source.
Sources
- Wegovy and Mounjaro summaries of product characteristics, section 5.2, electronic medicines compendium: medicines.org.uk/emc
- Retatrutide: published phase 1 pharmacokinetic data, listed on the How estimates work page; there is no UK summary of product characteristics
- The Dose Club, How estimates work (page on this site)
This article is information, not medical advice. Talk to your prescriber about your treatment.
- app
- level chart
- estimates