# Tirzepatide Dosage: The Trial and Label Record > Tirzepatide dosage as documented in the FDA label and clinical-trial literature — the 2.5 to 15 mg titration schedule, once-weekly subcutaneous injection, half-life, and what the SURPASS and SURMOUNT programmes studied. ## The short version Tirzepatide is a prescription medicine injected subcutaneously (just under the skin) once a week. The FDA-approved label documents a stepwise titration schedule: starting at 2.5 mg once weekly for four weeks, then increasing by 2.5 mg every four weeks as tolerated, up to a maximum of 15 mg once weekly. The three maintenance doses studied across the SURPASS and SURMOUNT phase 3 programmes were 5 mg, 10 mg, and 15 mg once weekly. The drug has an approximately five-day elimination half-life — consistent with once-weekly dosing — which is achieved through the fatty diacid modification that gives the molecule high albumin affinity [1] [7]. This page summarises the tirzepatide dosage record from the published clinical-trial and label literature. It does not recommend a dose or course of treatment for any individual. ## Tirzepatide dosage: the FDA label and titration schedule The FDA prescribing information (approved label, May 2022, updated for the obesity indication November 2023) documents the following tirzepatide dosage schedule [7]: - **Starting dose:** 2.5 mg subcutaneous once weekly for four weeks. The 2.5 mg starting dose is used for titration only — it was not studied as a maintenance dose for efficacy in the phase 3 trials. - **Titration:** Increase by 2.5 mg every four weeks to reach a maintenance dose. - **Maintenance doses:** 5 mg, 10 mg, or 15 mg once weekly (maximum dose 15 mg once weekly). - **Target maintenance dose:** The label does not specify a single target. In the SURPASS programme for type 2 diabetes, all three maintenance doses (5, 10, and 15 mg) were studied; in the SURMOUNT programme for obesity, SURMOUNT-5 randomised participants to their maximum tolerated dose (10 or 15 mg). The label indicates the dose should be individualised based on glycaemic response and tolerability. The label also advises that a lower dose of a concomitant secretagogue (such as a sulfonylurea) or insulin may be needed to reduce the risk of hypoglycaemia when tirzepatide is added to those agents [7]. ## Tirzepatide dose: what the phase 3 trials studied The SURPASS programme in type 2 diabetes and the SURMOUNT programme in obesity both used three dose levels as primary trial arms: 5 mg, 10 mg, and 15 mg once weekly, reached via stepwise titration from 2.5 mg. In SURMOUNT-1 (n=2539, 72 weeks, adults with obesity without diabetes), mean body weight change: -15.0% at 5 mg, -19.5% at 10 mg, -20.9% at 15 mg versus -3.1% with placebo [4]. Dose response was clear and consistent. In SURPASS-2 (n=1879, 40 weeks, adults with type 2 diabetes): HbA1c reduction was 2.01 percentage points at 5 mg, 2.24 at 10 mg, and 2.30 at 15 mg — all superior to the comparator at 1.86 percentage points [3]. In SURMOUNT-5 (n=751, 72 weeks, adults with obesity without diabetes), participants were randomised to their maximum tolerated tirzepatide dose (10 or 15 mg). Mean body weight change was -20.2% versus -13.7% with the maximum tolerated dose of the comparator (1.7 or 2.4 mg once weekly) [5]. Gastrointestinal adverse events were most frequent during dose escalation and generally eased at maintenance doses. In SURMOUNT-1, the protocol specified a 20-week escalation period from 2.5 mg to the assigned maintenance dose of 5, 10, or 15 mg [4]. ## Tirzepatide injection: route, site, and pharmacokinetics **Tirzepatide injection route.** The only route studied across the entire phase 3 SURPASS and SURMOUNT programmes is subcutaneous injection — administered under the skin, not intravenously. All approved marketing is subcutaneous. **Half-life.** The elimination half-life of tirzepatide in humans is approximately five days, consistent with albumin-binding via the fatty-diacid modification and supporting once-weekly dosing [1]. A population pharmacokinetics analysis across the phase 3 programme confirmed steady-state exposure was reached within approximately four to five weeks on once-weekly dosing [33]. **Metabolism and excretion.** In humans administered a radiolabelled dose, renal excretion was the principal elimination route (approximately 66% urine, approximately 33% faeces). Tirzepatide is metabolised via proteolytic cleavage of the amino acid backbone, beta-oxidation of the C20 diacid moiety, and amide hydrolysis, with intact parent drug the major circulating component [34]. **Hepatic impairment.** A clinical pharmacology study found hepatic impairment did not produce clinically meaningful changes in tirzepatide exposure warranting dose adjustment [33]. **Storage.** The marketed formulation is refrigerated. Specific reconstitution and storage parameters are formulation-dependent and documented in the prescribing label. This site does not provide product-specific storage guidance. ## Tirzepatide dosage research context: what the literature addresses The tirzepatide dosage literature is extensive by the standards of a relatively new prescription medicine. Key published pharmacokinetic and dosing-context sources include: - The Coskun 2018 discovery paper (Mol Metab), which reported the first phase 1 single- and multiple-ascending-dose data in healthy subjects and a 4-week proof-of-concept in type 2 diabetes, supporting once-weekly dosing [1]. - The Urva 2020 paper (Diabetes Obes Metab) characterising the transient delay in gastric emptying and its attenuation with continued dosing — a mechanism directly relevant to dosing frequency and the perioperative considerations covered on the effects page [13]. - The population PK analysis (Pankratz J et al., CPT Pharmacometrics Syst Pharmacol 2024) characterising tirzepatide exposure across the phase 3 programme [33]. - The ADME paper (Martin JA et al., Eur J Pharm Sci 2024) documenting absorption, distribution, metabolism, and excretion in humans, rats, and monkeys [34]. All tirzepatide dosage information on this site is drawn from the peer-reviewed clinical-trial literature and the FDA prescribing label. This page does not recommend a dose for any individual and does not constitute medical advice. --- Peer-reviewed trial findings on tirzepatide, walked through step by step — not a prescription, not a clinic, not a vendor.