The eighteenth month, and the conversation that should have happened in the third
What the trials measured was continuation against withdrawal. What patients want to know is continuation at a lower dose, and that study has largely not been done.
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The practice is near-universal, clinically sensible, and supported by observational data rather than randomised comparison. We say which is which.
Read the protocols rather than the labels and a consistent provision appears: escalation may be delayed if the participant is not tolerating the current dose. STEP, SURMOUNT and SURPASS all contained versions of it, and the trial results everybody quotes were produced by populations exercising it. The efficacy figures in circulation are therefore not the product of a rigid ladder. They are the product of a flexible one, applied by trial staff with weekly contact and a strong incentive to keep participants enrolled. The label reports the ladder and drops the flexibility, which inverts the emphasis of the evidence.
The pivotal protocols in this class permitted escalation to be delayed. In the semaglutide obesity programme, participants unable to tolerate a dose increase could remain at the previous dose and attempt escalation later; the tirzepatide programme contained comparable provisions, with defined windows and a limit on how long a participant could remain below target before being counted as not having reached it.
This matters for how the efficacy figures should be read. The mean weight reductions quoted from STEP and SURMOUNT were produced by populations in which a meaningful minority spent time below their assigned target dose. The trials therefore already contain the effect of flexible titration, and the flexible approach is not a departure from the evidence but part of how the evidence was generated.
What the labels carry forward is the ladder. What they largely omit is the permission. A prescriber who reads only the label sees a fixed calendar; a prescriber who reads the trial documentation sees a calendar with a documented escape valve. The Journal has raised this with two regulatory affairs specialists, both of whom regarded it as a known and unglamorous gap in how trial conduct is translated into prescribing information.1
Holding a dose because of symptoms is a decision with a review date. Remaining at a dose because the schedule was never revisited is drift. From the outside the two are indistinguishable, and only one of them is a plan.
The evidence on deviating from four-week steps is observational and one-sided. Slower escalation — five, six or eight weeks per rung — is reported by clinicians to reduce early discontinuation, is consistent with the tachyphylaxis data, and has never been randomised against the standard interval in a trial of adequate size. Faster escalation has no supporting rationale we can identify and a clear kinetic argument against it.
What can be said with confidence is that the cost of going slower is bounded and calculable: a longer time to target exposure, and therefore a later arrival at the efficacy plateau. Because the plateau itself sits at sixty weeks or beyond, adding four or eight weeks to the escalation phase is a small fraction of the treatment course. The cost of going faster is a higher probability of discontinuation, and discontinuation costs the entire effect.
That asymmetry is the strongest thing the Journal is willing to say on the subject. It is an argument from consequence rather than from trial data, and we flag it as such rather than dressing it as a finding.2
The plateau is predictable, is predicted, and is almost never mentioned to anyone before it happens.
On week sixtyHolding works because two of the three things a person notices attenuate on their own. Gastric emptying delay, measured by scintigraphy and by breath test, is largest early in exposure at a given dose and diminishes over subsequent weeks while the drug is continued unchanged. Nausea incidence in the trials follows a comparable trajectory: it peaks in the weeks following each escalation and declines toward a lower background.
The third thing — reduced appetite and early satiety — attenuates considerably less, which is the whole reason holding is worth doing rather than simply reducing. A held dose loses much of its unwanted effect and keeps most of its wanted one.
The magnitude of this adaptation is not enormous and it is not universal. Some proportion of people find that symptoms at a given dose do not settle at all over eight or twelve weeks, and for them the dose is simply above their ceiling. Distinguishing a slow adapter from a person at their limit cannot be done in advance, which means holding is also a diagnostic manoeuvre: it converts an unanswerable question about tolerance into an answerable question about time.3
| Molecule | Step | Absolute increase | Fold increase |
|---|---|---|---|
| Semaglutide | 0.25 → 0.5 mg | 0.25 mg | 2.00 |
| Semaglutide | 0.5 → 1.0 mg | 0.5 mg | 2.00 |
| Semaglutide | 1.0 → 1.7 mg | 0.7 mg | 1.70 |
| Semaglutide | 1.7 → 2.4 mg | 0.7 mg | 1.41 |
| Tirzepatide | 2.5 → 5 mg | 2.5 mg | 2.00 |
| Tirzepatide | 7.5 → 10 mg | 2.5 mg | 1.33 |
| Tirzepatide | 12.5 → 15 mg | 2.5 mg | 1.20 |
| Identical absolute increments produce steadily smaller proportional increases as the ladder rises. Exposure-response depends on the ratio, which is why the lower rungs are the demanding ones. | |||
The practice that has emerged across this class, without ever being formally codified, runs roughly as follows. Start at the initiation dose. Escalate when the current dose is comfortable enough that a person is eating normally, keeping fluids down, and not organising their week around symptoms. Do not escalate in the week of a symptom flare. If a rung is intolerable, step back to the previous one and try again later. If a rung is producing an adequate result, consider stopping there.
Every clinician we spoke to described something within a small variation of that, and none of them could point to a trial of it. It is a reasonable synthesis of the pharmacokinetics, the tachyphylaxis data and a great deal of accumulated observation.
The Journal has a specific position on this. The absence of randomised support for tolerability-led escalation is a real gap and should be closed, but its absence is not a reason to prefer the printed calendar, which has no randomised support either. Between two unrandomised schedules, the one that responds to information about the individual is the better bet. We say that as an editorial judgement rather than as a report of evidence.
Dose reduction in this class carries a stigma that the pharmacology does not justify. Because the ceiling is set by tolerability and tolerability varies severalfold between people, the only way to find an individual ceiling is to move until it is reached and then move back. A reduction is the second half of that measurement.
There is a practical detail worth stating. Reduction takes effect on the same kinetics as escalation, which means the relief is not immediate: a person dropping from 15 mg to 10 mg is still carrying substantial exposure from the higher dose for a fortnight, and concluding after five days that the reduction has not helped is premature.
There is also an arithmetic trap for vial users. Halving a dose halves exposure at steady state, but the transition takes three to four weeks, and during that transition the person is at neither dose. Anybody adjusting downward to escape a symptom should expect the answer to arrive on a three-week timescale, not a three-day one.
Three conventions govern the numbers in this file. Weight-change figures are quoted with the estimand named, because the treatment-policy and trial-product analyses in the obesity programmes differ by two to three percentage points and secondary coverage habitually mixes them. Doses are quoted as the weekly amount, not as a pen volume or a unit count, because volume and units depend on concentration and concentration varies. And where a figure derives from a responder analysis rather than a primary endpoint, we say so.
Where we describe practice rather than evidence, the text says so explicitly. A substantial part of what is known about titration in this class is craft knowledge held by clinicians, and reporting it is legitimate journalism. Presenting it as trial data is not.
Nothing in this file is medical advice. The Journal does not recommend doses, schedules, products or suppliers. Several compounds discussed here are sold for research use only and are not approved for human use in any jurisdiction. Decisions about treatment belong with a licensed clinician who has examined the person concerned.
Nothing above is medical advice. This department reports what was studied, what was printed and what is practised, and the distance between the three is the subject rather than a recommendation about which to follow.
One question is worth putting to the sponsors of the next generation of these molecules, and we intend to keep putting it. Escalation is the phase in which most discontinuation occurs, and discontinuation costs the entire treatment effect. A dose-escalation trial would be inexpensive relative to a cardiovascular outcome programme and would settle the most frequently asked practical question in the field. Nobody has run one.
Selected from correspondence received on this article. Writers are identified by initial, surname and city, verified before printing. Replies are from the desk that filed the piece or from the standards editor. Write to letters@compoundjournal.com.
Steady state is reached at different times for different compounds in this class, and holding decisions made before it is reached are being made on incomplete information about that step.
— R. Perreault, Trois-Rivières, QC
Where a trial permitted a delay in escalation, the proportion who used it is reported in some papers and is an interesting number in its own right. It is closer to real practice than the nominal schedule.
— M. Bogdanović, Podgorica
Re-titration after an interruption is the question I am asked most often and the one with the least published guidance. The pharmacokinetic reasoning is straightforward: after several half-lives the exposure has gone, and resuming at the previous dose is resuming without the accommodation that produced tolerance.
— M. Lindqvist, Linköping
Straightforward pharmacology and almost no trial data, which is an uncomfortable combination and one worth naming as such.
Duration of the published trials is short relative to the question. Whether a plateau at month twelve is stable at month thirty-six is a question no study in this class has answered, and it is answered confidently in general discussion.
— R. Duffy-Behan, Athlone
Where the evidence stops is a fact readers are entitled to, and we try to print the horizon of the underlying study beside any curve we describe.
What the trials measured was continuation against withdrawal. What patients want to know is continuation at a lower dose, and that study has largely not been done.
The evidence base is thin and the document says so, which is to its credit.
The evidence base is thin and the document says so, which is to its credit.
The evidence base is thin and the document says so, which is to its credit.
Roughly four to seven per cent of trial participants discontinued for adverse events, mostly gastrointestinal, mostly during escalation. That is the empirical size of the…
Receptor pharmacology is strong on average effects and almost silent on individual variation. That gap is where most reader questions live.