Frequently asked questions

Different sites use different pharmacokinetic models and different reference-dose normalizations. We use a transparent 3-tier model (advanced, linear-regression, simple) plus an inherited tier, all documented on our methodology page. If a curve looks different here, the difference is usually because we apply a dose-scaling exponent for compounds where peak concentration is known to be non-linear in dose (notably testosterone esters).

Because you’re dosing repeatedly. Half-life describes the decay of a single dose in the absence of further input. With ongoing dosing, each new dose is added on top of residual drug, so the curve is the superposition of many individual dose curves. The combined curve doesn’t drop to 50% after one half-life because the newest dose is still near its peak. This accumulation is what drives the approach to steady state.

Use our contact form and include the compound name and, ideally, a link to a peer-reviewed pharmacokinetic source. We add compounds as reliable pharmacokinetic data becomes available. Compounds without usable half-life or bioavailability data use our “inherited” or “simple” model tiers and are clearly labeled.

No model will precisely predict an individual’s blood levels. Our curves are simplified one-compartment approximations meant to illustrate patterns — accumulation, timing, and peak-to-trough behavior. Real levels vary with genetics, body composition, organ function, and injection technique. Use the per-compound “Adjust levels” slider to explore sensitivity, and treat the curve as educational, not predictive.

We update the database as new peer-reviewed pharmacokinetic data is published or as reliable sources correct earlier estimates. Every compound page links to its source so you can see exactly where each value came from. Major updates are logged on our changelog.

Yes. Add the same compound twice (or more) using “Add compound,” then set different doses and schedules for each row. For example, you can overlay 120 mg once weekly against 60 mg twice weekly to see how frequency affects the peak-to-trough ratio. Each row appears as a separate colored line.

Toggle the “Calendar” button in the plotter sidebar. In calendar mode you click any date and add a dose (compound + milligrams) directly to that day — ideal for irregular or as-needed schedules. You can add multiple doses per day. The plotter reverse-engineers the schedule from your entries and computes the curve. Switch back to “Schedule” mode any time.