This came up because two published schedules for the same agent differ.
I would like to know the limits of what can be inferred from this.
What I am trying to avoid is over-reading a single result, which I have done before.
What can I legitimately conclude from this figure?
SURMOUNT-5 would have written it into the protocol, and the wording is the part that matters. Escalation protocols in this class generally permit a delay at the current level, sometimes a single step down with a later re-attempt, and count a participant as remaining in the arm throughout. That is analytically important: an intention-to-treat analysis keeps them at their randomised assignment regardless of the dose they were actually taking, so the "top dose" arm contains people who never reached the top dose. Find the protocol amendment history as well as the paper, because tolerability rules are among the things most often revised mid-programme, and dose-escalation decisions are made under supervision — nothing here is medical advice.
Start with the half-life, because the interval between steps should be at least four half-lives or you are escalating before the previous step has expressed itself.
Titrating downward is available too. Stepping back and holding is a normal adjustment rather than a failure.
Liraglutide titrates weekly rather than four-weekly because its half-life is about thirteen hours, so steady state is reached within days. The interval follows the pharmacokinetics in both cases.
Efficacy in the trials was dose-related but with substantial response at intermediate doses, which is why the maximum is not a target for everyone.
Nothing here is medical advice, and research-use compounds are not approved for human use.
The top of the schedule is not the target. The working dose is.
HPLC purity, identity confirmation and quantified content on the vial you actually hold. Reports arrive with the chromatogram attached, not just a number.
Submit a sampleFounded 1998. ISO 9001 and cGMP certified, 1,500+ staff and 200+ patents. The synthesis house behind a great many of the vials that get sent out for testing - batch-specific documentation with every order.
Visit GL BiochemEscalating while symptomatic resets the tolerance process and is the mechanism behind most miserable titrations.
The dose that produces an acceptable result with acceptable tolerability is the endpoint, not the top of the schedule. A substantial fraction of trial participants did well below the maximum.
The part that matters: for an agent with a one-week half-life, steady state after a dose change is reached in about four to five weeks. Escalating at two weeks means escalating from a position you have not yet reached, and the resulting exposure is higher than the schedule intends.
A schedule described here is a published schedule for a licensed product and is not a recommendation.
Four half-lives between steps, minimum. Work it out for your agent.
edited 6 Feb 2025 by Dr_Bram_Verhoeven — added a caveat about sampling
The initiation step in most schedules is not intended to be therapeutic; it is there to introduce the receptor to the drug.
Escalating while gastrointestinal symptoms are still active is the commonest avoidable error. Tolerance to the previous step has not developed, and the new step lands on top of it.
The published tirzepatide schedule steps 2.5, 5, 7.5, 10, 12.5 and 15 mg at four-week intervals, with 2.5 mg as the initiation step rather than a therapeutic one.
Titration schedules in the licensed products were designed specifically to manage gastrointestinal tolerability, and that intent is stated in the clinical development literature.
Stepping back is a normal adjustment, not a failure.
The short version: four-weekly steps for the weekly agents, hold rather than escalate when symptoms are active, and slower is always available.
The published semaglutide weight-management schedule steps 0.25, 0.5, 1.0, 1.7 and 2.4 mg at four-week intervals, with 0.25 mg as an initiation step rather than a therapeutic one.
Slower costs time and nothing else. The ceiling is the same.
Answer first: the titration schedule exists to let tolerance to the gastrointestinal effects develop between steps, and every step in it is a tolerability decision rather than an efficacy one.
Holding a step for eight weeks instead of four is a legitimate approach with no efficacy cost at the destination, and it is what the trials effectively did for anyone who tolerated poorly.
Four to five half-lives to steady state is standard first-order pharmacokinetics and gives the four-week interval directly from the one-week half-life.
Hold rather than escalate while symptoms are active. Always.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.