# Tirzepatide / Get — A Field Manual to the Dual-Incretin Evidence Base > Plain-language overview of tirzepatide: dual GIP/GLP-1 mechanism, SURPASS and SURMOUNT trial results, FDA-approved indications, dose escalation, and the October 2024 shortage resolution that ended the compounding window. An illustrated, step-by-step walk through what tirzepatide is, how the dual-incretin mechanism works, what the FDA has approved it for, and what the October 2024 shortage resolution actually changed. ## The short version Tirzepatide is a once-weekly injected drug approved by the FDA for type 2 diabetes (2022), obesity (2023), and obstructive sleep apnea (2024). It is the first medicine to activate two gut-hormone signals at once — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) — which is why researchers call it a *twincretin*. Both are natural signals the gut sends after meals to trigger insulin release. By hitting both at once, tirzepatide produced larger reductions in blood sugar and body weight than older drugs that only target GLP-1. In the biggest obesity trial (SURMOUNT-1), average weight loss reached 22.5% at the 15 mg dose. A weekly injection is enough because the molecule has a fatty-diacid tail that binds to a blood protein and keeps it circulating about five days. This manual covers the mechanism, the trial results, the FDA-labeled dose schedule, and what changed when the shortage was resolved in October 2024. For what patients say about real-world effects — benefits, side effects, and cautions — see [the effects page](/effects). ## What tirzepatide is, in one panel Tirzepatide is a once-weekly injected peptide drug. It is the first marketed *twincretin* — a single synthetic 39-amino-acid molecule that activates two distinct gut-hormone receptors at the same time: the **GIP** receptor (glucose-dependent insulinotropic polypeptide) and the **GLP-1** receptor (glucagon-like peptide-1) [1]. The peptide carries a long fatty-diacid tail that binds tightly to plasma albumin. That tail is the reason a single weekly injection is enough — without it, the molecule would be cleared in hours [12]. With it, the half-life stretches to roughly five days, and steady state is reached after about four weeks of weekly dosing [12]. The U.S. Food and Drug Administration has approved tirzepatide for three separate indications so far: type 2 diabetes mellitus (May 2022), chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity (November 2023), and moderate-to-severe obstructive sleep apnea in adults with obesity (December 2024) [17]. The OSA indication was the first time any medication had ever been approved by the FDA specifically for obstructive sleep apnea [8]. ## Why this site exists If you type *get tirzepatide* into a search bar in 2026, you are arriving at a question that has shifted a lot in the last two years. Through 2023 and most of 2024, tirzepatide was on the FDA's drug shortage list, and that shortage opened a compounding window — state-licensed 503A pharmacies and 503B outsourcing facilities could produce non-brand versions of the molecule, and a wave of telehealth platforms grew up around dispensing them [18]. On **October 2, 2024**, the FDA issued a declaratory order announcing that the tirzepatide shortage was resolved. The agency reaffirmed that determination on December 19, 2024, after litigation [18]. That removal from the shortage list closed the compounding exception. State-licensed 503A pharmacies had a grace period through **February 18, 2025**, and 503B outsourcing facilities had until **March 19, 2025**, after which compounded tirzepatide could no longer be lawfully dispensed under the shortage-list exception [19]. This site is not a pharmacy, not a clinic, and not a telehealth platform. It does not sell, dispense, or facilitate the acquisition of any product. It is a field manual — an editorial summary of the published evidence and the regulatory record, organized so a reader can understand what the molecule does, what the trials showed, and what the current lawful access pathway in the United States looks like. ## What the trials showed, in one breath Tirzepatide is among the most thoroughly studied peptide drugs of the last decade. A short tour: - In **SURPASS-1** (40 weeks, drug-naive adults with type 2 diabetes), the 15 mg dose reduced HbA1c by 2.07% versus a small placebo increase of 0.04% [1]. - In **SURPASS-2** (40 weeks, head-to-head against once-weekly semaglutide 1 mg), tirzepatide 15 mg achieved a 2.30% HbA1c reduction versus 1.86% for semaglutide, with roughly twice the weight loss (~12.4 kg vs ~6.2 kg) [2]. - In **SURMOUNT-1** (72 weeks, adults with obesity without diabetes), mean body-weight reductions were 16.0%, 21.4%, and 22.5% at the 5, 10, and 15 mg doses versus 2.4% on placebo [4]. - In the **SURMOUNT-1 176-week extension**, the risk of progression to type 2 diabetes in adults with obesity and prediabetes fell by 94% versus placebo [5]. - In **SURMOUNT-OSA** (52 weeks), the apnea-hypopnea index dropped by roughly 25-29 events per hour [8]. That trial became the basis for the December 2024 OSA approval. - In **SUMMIT** (heart failure with preserved ejection fraction and obesity), tirzepatide reduced a composite of cardiovascular death or worsening heart failure events by about 38% [9]. ## How to read the rest of this manual The remaining chapters take each of those threads slowly: - **/research** unpacks the dual-receptor mechanism, the biased-agonism signaling pattern at GLP-1, and the full SURPASS, SURMOUNT, SURMOUNT-OSA, SUMMIT, and SYNERGY-NASH programs panel by panel [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]. - **/dosage** describes the FDA-labeled dose-escalation schedule, the rationale for the 4-week minimum step interval, the missed-dose rule, and the pharmacokinetics that justify a once-weekly schedule [13] [17]. - **/faq** answers the questions that bring most readers to a page titled *get tirzepatide*, including the compounding question, the side-effect question, the cost question, and the *what happens if you stop* question. - **/references** lists every study cited on this site with DOI and PubMed links. - **/about** explains who publishes this site and the editorial standards behind it. The whole site is also available as plain Markdown — every page has a `.md` sibling, and `/llms.txt` and `/llms-full.txt` exist at the root for language models indexing the content. --- An illustrated editorial digest of the published tirzepatide evidence — not a clinic, not a pharmacy, not a prescription.