The steps get smaller as the ladder gets higher, and that is deliberate

We have looked for a randomised comparison of escalation intervals — same molecule, same target dose, four-week steps against two-week steps or six-week steps — and we cannot find one of any size. There are protocol amendments, there are post-hoc tolerability analyses, and there is a great deal of clinical convention. What there is not, thirty million prescriptions into this class, is a trial that answers the single most frequently asked practical question about it. The Journal regards that as the most striking evidence gap in the field, and we intend to keep saying so.

The semaglutide ladder, rung by rung

For weight management, the approved escalation runs 0.25 mg weekly for four weeks, then 0.5 mg, then 1.0 mg, then 1.7 mg, reaching 2.4 mg at week seventeen. For glycaemic indications the ladder is shorter and the maximum lower: 0.25 mg, then 0.5 mg, then 1.0 mg, with a 2.0 mg option added later on the strength of a dedicated dose-comparison study.

Two features are worth noticing. The starting dose is explicitly sub-therapeutic — 0.25 mg is a tolerability rung, not a treatment dose, and describing it as a low dose rather than an initiation dose causes real confusion. And the ratios narrow as the ladder rises: two doublings, then a 1.7-fold step, then a 1.41-fold step.

The 2.4 mg dose was selected on the basis of the phase 2 dose-ranging programme and carried into the STEP trials, where it produced a mean weight reduction of about fifteen per cent at sixty-eight weeks against roughly two and a half per cent on placebo.¹ That is the number the ladder exists to reach, and the ladder itself was never the subject of the trial.

The arithmetic of a step

A dose increase should be described as a ratio, because receptor occupancy and the exposure-response relationship are governed by proportional change rather than by absolute milligrams. On the semaglutide weight-management ladder the ratios are 2.00, 2.00, 1.70 and 1.41. On the tirzepatide ladder they are 2.00, 1.50, 1.33, 1.25 and 1.20.

Two consequences follow. The first is that the early rungs are the hard ones, in both ladders, and the widespread expectation that titration gets progressively more difficult is backwards. The second is that a person who has tolerated the doubling at the bottom of the ladder has already survived the largest proportional insult the schedule contains.

There is a third, less obvious consequence for anyone dosing from a multi-dose vial rather than a fixed pen. Fixed-pen users move in the ratios above. Vial users can move in any ratio they like, including ratios small enough to be pharmacologically meaningless and large enough to be foolish. Freedom of increment is the single largest practical difference between pen and vial administration, and the arithmetic is the only guardrail.

Accelerated and decelerated schedules

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

A short glossary, because the terms get swapped

Initiation dose: the first rung, chosen for tolerability and generally sub-therapeutic. Not a low treatment dose. Target dose: the dose a protocol or prescriber intends to reach. Maintenance dose: the dose continued once the intended effect is achieved. Maximum approved dose: the highest dose in the label, set by the studied range and the tolerability ceiling.

Escalation interval: the time between increments. Hold: deliberately remaining at a rung beyond the standard interval. Re-titration: re-ascending after exposure has been substantially cleared. Dose-limiting: describing an effect severe enough to prevent escalation, which is a property of the person and the dose jointly, not of the drug alone.

Steady state: the condition in which drug entering the body equals drug leaving it. Accumulation ratio: steady-state average concentration divided by first-dose average concentration. Precision here matters more than it sounds: a large share of the correspondence this desk receives about titration turns out on inspection to be a disagreement about which of these words the writer meant.

Five things about titration nobody can currently answer

First, the optimal escalation interval. No adequately powered randomised comparison of intervals at a fixed target dose exists for any molecule in this class.

Second, the optimal hold duration for a person who has not adapted at four weeks. Practice ranges from four to twelve weeks on no comparative evidence at all.

Third, the lowest maintenance dose that preserves a result. The withdrawal trials compared full dose with nothing.

Fourth, whether tolerability at one rung predicts tolerability at the next. Clinicians assume it does, plausibly, and the published dose-ranging data is not analysed in a way that answers the question.

Fifth, whether any measurable baseline characteristic predicts the ceiling. Nothing published does so usefully, which mirrors the situation for efficacy: mean behaviour in this class is well characterised and individual variation is not.³

The Journal lists these not as a complaint about researchers but as a map of where confident advice is currently outrunning its evidence. Anyone offering a precise answer to any of the five is offering an opinion, and should be read as doing so.

The Journal ends where the evidence does. Escalation intervals in this class rest on a kinetic argument that is sound and on a randomised comparison that does not exist. Dose holding rests on a documented adaptation and on clinical consensus. Maintenance rests on two withdrawal trials that answered a narrower question than the one readers ask. None of that makes the current practice wrong; it makes it provisional, and provisional practice deserves to be described as such rather than printed as a table.