Published-trial titration record
Tirzepatide: published trial titration schedule
Tirzepatide's UK research and licensed dosing schedules are anchored to the SURMOUNT and SURPASS Phase 3 programmes, which used identical titration steps. Weekly subcutaneous administration is the only route studied; doses escalate at four-week intervals to manage gastrointestinal tolerability. The 15 mg maintenance dose used in SURMOUNT-1 produced ~22% mean weight reduction at 72 weeks.
Trial anchor
SURMOUNT-1 (NEJM 2022, PMID 35658024) for the 24-week titration schedule; SURPASS-2 (NEJM 2021, PMID 34170647) for the type-2-diabetes context.
Full molecule profile: Tirzepatide
Published titration schedule (trial record)
| Step | Trial-arm dose | Notes |
|---|---|---|
| Week 1-4 | 2.5 mg weekly | Starting dose. Not a therapeutic dose — initiation only. |
| Week 5-8 | 5 mg weekly | First therapeutic step. ~10-12% mean weight reduction at 72w in trials. |
| Week 9-12 | 7.5 mg weekly | Increase by 2.5 mg per step if tolerated. |
| Week 13-16 | 10 mg weekly | Mid-range maintenance for participants intolerant of higher doses. |
| Week 17-20 | 12.5 mg weekly | Penultimate step. |
| Week 21+ | 15 mg weekly (maintenance) | Highest licensed maintenance dose; SURMOUNT-1 endpoint dose. |
Maintenance phase (as reported)
Most participants in SURMOUNT-1 reached 15 mg by week 20 and continued through week 72. Investigators retained discretion to hold the dose at 10 or 12.5 mg in the case of intolerance — both lower doses produced substantial weight reduction (~15% and ~19% respectively).
Route & storage (trial protocol)
Subcutaneous via single-use prefilled KwikPen (abdomen, thigh, or upper arm — equivalent pharmacokinetics across sites). Store at 2-8°C; up to 21 days at room temperature (≤30°C) is permitted once. Do not freeze. Do not shake.
Missed-dose handling (trial protocol)
If a dose is missed and the next scheduled dose is more than 72 hours away, administer the missed dose. If less than 72 hours, skip and resume the regular schedule. Do not double-dose.
Methodological considerations
- Concomitant insulin or sulphonylureas: hypoglycaemia risk increases — those agents typically require dose reduction.
- Gastric-motility-sensitive medications (warfarin, levothyroxine): consider timing separation to account for delayed gastric emptying.
- Pregnancy: contraindicated. Discontinue ≥2 months before planned conception.
- Severe hepatic impairment: limited data; use cautiously.
What this evidence does not prove
- · A published titration arm is not a prescription, recommendation or self-administration guide.
- · Trial-arm doses apply only within the studied population, comparator, duration and primary endpoint.
- · Individual suitability requires qualified clinical assessment where licensed; investigational compounds require authorised research oversight.
- · Off-label, compounded, grey-market or self-supplied versions of the same active ingredient may have substantially different identity, purity, sterility and pharmacokinetics.
FAQs
- Why is the starting dose 2.5 mg not therapeutic?
- The 2.5 mg dose is a four-week tolerance-initiation step rather than an effective therapeutic dose. Trial data shows minimal weight or glycaemic effect at 2.5 mg; the dose exists solely to expose the patient gradually to GLP-1/GIP signalling and reduce the dose-dependent gastrointestinal adverse event rate that intensifies at the 5 mg step and above.
- Can tirzepatide be stopped abruptly?
- Yes — tirzepatide does not produce physiological dependence and abrupt discontinuation is not associated with rebound effects beyond the expected attenuation of appetite suppression. Trial extension data (SURMOUNT-4) shows substantial weight regain in the months after discontinuation, consistent with chronic-disease pharmacology rather than withdrawal physiology.
- Is a 20 mg dose under investigation?
- No registrational programme has tested doses above 15 mg weekly. The dose-response curve appears to plateau between 10 and 15 mg in published trials, and the gastrointestinal adverse-event rate increases steeply beyond 15 mg in early-phase data — making higher doses unlikely to advance through Phase 3.