# Tirzepatide dosing — FDA-labeled titration schedule, half-life, storage > The FDA-labeled tirzepatide dose titration schedule (2.5 mg starting dose, monthly steps to 5, 7.5, 10, 12.5, 15 mg), elimination half-life, route, storage requirements, and renal/hepatic considerations. The label, summarized. Tirzepatide is FDA-approved by prescription only. The schedule below summarizes the U.S. prescribing information and published trial protocols. It is reference material, not personal medical advice. ## Route and frequency Tirzepatide is administered as a subcutaneous injection — under the skin — once weekly. The label specifies three rotating injection sites: the abdomen, the front of the thigh, or the back of the upper arm. The day of the week can be changed if needed, as long as the most recent dose was at least three days earlier [15][17]. The formulation comes in pre-filled single-dose pens and single-dose vials at each labeled strength. There is no oral formulation. ## Titration — the only way the label is dosed Every patient starts at 2.5 mg once weekly. That starting dose is explicitly non-therapeutic — it exists only to let the digestive system acclimate to slowed gastric emptying, which is the source of most of the early side effects [16][17]. The full titration ladder per the FDA label: - Weeks 1-4: 2.5 mg once weekly (non-therapeutic, for tolerability) - Week 5 onward: 5 mg once weekly - If additional glycemic or weight control is needed: increase in 2.5 mg increments at intervals of at least 4 weeks - Approved maintenance doses: 5 mg, 10 mg, or 15 mg once weekly - Maximum: 15 mg once weekly The intermediate strengths (7.5 mg and 12.5 mg) exist as titration stops to slow the climb; they are not labeled maintenance doses. The phase 3 trials used essentially this same titration scheme, which is why GI side effects in those trials clustered during dose escalation and abated at steady-state [16]. ## Half-life, steady state, and what happens at the end of the week The population pharmacokinetic model puts the terminal elimination half-life at approximately five days (about 120 hours), with median time to peak concentration of 24 hours after injection (range 8 to 72 hours) [15]. Mean absolute subcutaneous bioavailability is roughly 80%. Because the half-life is much longer than the dosing interval, drug concentrations do not return to baseline between doses. Steady state — the point at which weekly intake roughly equals weekly clearance — is reached after about four weekly doses. From a patient perspective, this is why the first month does not feel like the months that follow: exposure is still climbing, side effects are highest, and weight and glycemic responses have not yet plateaued. ## Storage and stability Pre-filled pens and vials require refrigeration at 2 to 8 degrees Celsius (about 36 to 46 degrees Fahrenheit). They can be stored at room temperature below 30 degrees Celsius (86 degrees Fahrenheit) for up to 21 days before use. The product must be protected from light and must not be frozen; a frozen pen or vial is discarded [17]. ## Renal and hepatic adjustments Per the FDA label, no dose adjustment is required for renal impairment — including end-stage renal disease — or for hepatic impairment. The pop-PK analysis found no clinically meaningful effect of renal function, hepatic function, sex, race, or body weight on tirzepatide exposure [15]. That said, severe gastrointestinal adverse events that lead to dehydration have been associated with acute kidney injury in post-marketing reports, particularly in patients with pre-existing renal disease. The label recommends adequate hydration and clinical monitoring of renal function when starting or escalating the dose in those patients. ## Co-administration with insulin or sulfonylureas Tirzepatide's incretin action is glucose-dependent, so the drug itself rarely causes hypoglycemia. However, when it is combined with insulin or a sulfonylurea, the risk of hypoglycemia rises substantially because those agents lower glucose independently of meal state. The label recommends considering a dose reduction of the insulin or sulfonylurea when tirzepatide is added, and the SURPASS-5 trial specifically observed lower hypoglycemia rates at higher tirzepatide doses (consistent with the larger glucose-lowering effect requiring less concomitant therapy) [6]. ## A note on compounded tirzepatide During the FDA-declared tirzepatide shortage that began in late 2022, U.S. compounding pharmacies were permitted to prepare non-FDA-approved versions under sections 503A and 503B of the Food, Drug, and Cosmetic Act. That shortage was officially resolved on October 2, 2024, and reaffirmed in a December 19, 2024 declaratory order. The 503A compounding period sunset on February 18, 2025, and the 503B period sunset on March 19, 2025. As of those dates, compounded tirzepatide is no longer permitted under U.S. compounding law. Any tirzepatide preparation outside the FDA-approved product is unapproved and has not been evaluated for identity, strength, quality, or purity by the FDA. ## References [6] Dahl D, et al. SURPASS-5: tirzepatide added to titrated insulin glargine. JAMA. 2022. doi:10.1001/jama.2022.0078 [15] Furihata K, et al. Population pharmacokinetics of tirzepatide. CPT: PSP. 2024. doi:10.1002/psp4.13110 [16] Rubino DM, et al. GI tolerability across SURMOUNT-1 to -4. Diabetes, Obesity and Metabolism. 2025. doi:10.1111/dom.16176 [17] Caruso I, et al. Real-world safety profile of tirzepatide (FAERS). J Endocrinol Invest. 2024. doi:10.1007/s40618-024-02441-z --- Not medical advice. This site does not sell any product and is not affiliated with any vendor or manufacturer.