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Glossary / Tirzepatide

Tirzepatide

Definition

Tirzepatide is Eli Lilly’s dual GLP-1/GIP agonist — sold as Mounjaro for type 2 diabetes and Zepbound for weight management — the current efficacy benchmark in the weight-loss category.

By Lithos Staff · Updated July 2026

At a glance
  • Eli Lilly’s dual agonist: Mounjaro and Zepbound
  • SURMOUNT trials set the current efficacy benchmark
  • LillyDirect vials anchor the cash-pay channel
  • Shortage resolved late 2024; compounding moved to the patient-specific pathway

Why tirzepatide moved the market

The SURMOUNT trials showed average weight reduction beyond what single-agonist GLP-1s had achieved, making Zepbound the request patients arrive with. Lilly leaned into cash-pay access earlier than its rival — single-dose vials through its LillyDirect self-pay channel at prices meaningfully below auto-injector list — a move that shaped how DTC programs structure tirzepatide offerings.

GLP-1 receptorGIP receptorTirzepatidedual agonistMounjarotype 2 diabetesZepboundweight + sleep apnea
Dual receptor activity, one molecule, two brands — with Zepbound adding a sleep-apnea indication in late 2024.

Program considerations

Tirzepatide programs run the standard GLP-1 playbook — clinician evaluation, molecule-specific titration, refill gating on check-ins — with two specifics: the vial-based cash channel means patient instruction on syringe draw rather than auto-injectors for some products, and demand routinely arrives pre-anchored on Zepbound specifically, which makes clinician-led therapy selection (rather than order-taking) both the compliant and the clinically right pattern. Its shortage ended in late 2024, moving compounded tirzepatide to the patient-specific pathway.

Mounjaro vs Zepbound

BrandIndicationCash channelNotes
MounjaroType 2 diabetesCoverage-ledDiabetes formularies; off-label weight use at clinician discretion
ZepboundWeight management + obstructive sleep apneaLillyDirect single-dose vialsThe on-label weight product; OSA indication (Dec 2024) strengthened the coverage story

Why it resets benchmarks

SURMOUNT’s roughly 21% average weight reduction at the top dose made Zepbound the arrival request — patients come in asking for it by name. The OSA indication broadened the clinical case and gave coverage conversations a second anchor. For programs, the operational specifics are the vial-based cash channel (syringe-draw instruction rather than auto-injectors) and the discipline of keeping therapy selection a clinician decision rather than an order form.

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Frequently asked questions

What is the difference between Mounjaro and Zepbound?

Same molecule, different indications: Mounjaro for type 2 diabetes, Zepbound for weight management — programs should align with the on-label product.

Is compounded tirzepatide available?

Through the patient-specific pathway — prescriptions reflecting documented individual clinical needs. The broad shortage-era window closed when the FDA declared the shortage resolved in late 2024.

Why do patients specifically request Zepbound?

Trial results and press coverage made it the perceived strongest option — which is exactly why therapy selection must remain a clinician’s decision, not a menu order.

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