Tirzepatide was approved for treatment of diabetes in the United States in May 2022,[10][14] in the European Union in September 2022,[12] in Canada in November 2022,[20] and in Australia in December 2022.[2] The US Food and Drug Administration (FDA) considers it to be a first-in-class medication.[21][22] It was approved by the FDA for weight loss in November 2023.[17][23] In November 2023, the UK Medicines and Healthcare products Regulatory Agency revised the indication for tirzepatide to include treatment for weight loss.[8][24] In December 2024, the FDA revised the indication for tirzepatide (as Zepbound) to include the treatment of moderate to severe obstructive sleep apnea.[11][18]
Medical uses
Tirzepatide (as Mounjaro) is indicated to improve blood sugar control in adults with type2 diabetes, as an addition to diet and exercise.[10][14]
Tirzepatide (as Zepbound) is indicated in combination with a reduced-calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in adults with obesity or adults with overweight in the presence of at least one weight-related comorbid condition;[11][17] and to treat moderate to severe obstructive sleep apnea in adults with obesity.[11]
Tirzepatide has demonstrated significant benefits in obese patients with a common type of heart failure, preserved ejection fraction (HFpEF) in a phase III trial.[25][26] Over two years, tirzepatide reduced the risk of major complications, including urgent heart failure visits, hospitalizations, increased diuretic treatment, and cardiovascular-related deaths, by 38% compared to placebo.[27]
Preclinical, phase I, and phase II clinical trials indicated that tirzepatide exhibits adverse effects similar to those of other established GLP-1 receptor agonists, such as dulaglutide. These effects occur largely within the gastrointestinal tract.[29] The most frequently observed are nausea, diarrhea, and vomiting, which increased in incidence with the dosage amount (that is, the higher the dose, the higher the likelihood of side-effects). The number of patients who discontinued taking tirzepatide also increased as the dosage increased, with patients taking 15 mg having a 25% discontinuation rate vs 5.1% for 5 mg patients and 11.1% for dulaglutide.[30][clarification needed] To a slightly lesser extent, patients also reported reduced appetite.[29] Other side effects reported were dyspepsia, constipation, abdominal pain, dizziness, and hypoglycaemia.[31][32]
A systematic review, published in 2024, found that tirzepatide is well tolerated and is not associated with pancreatitis.[33]
Tirzepatide has a greater affinity to GIP receptors than to GLP-1 receptors, and this dual agonist behavior has been shown to produce greater reductions of hyperglycemia compared to a selective GLP-1 receptor agonist.[15]Signaling studies reported that tirzepatide mimics the actions of natural GIP at the GIP receptor.[37] At the GLP-1 receptor, though, tirzepatide shows bias towards cAMP (a messenger associated with regulation of glycogen, sugar, and lipid metabolism) generation, rather than β-arrestin recruitment. This combination of preference towards GIP receptor and distinct signaling properties at GLP-1 suggest this biased agonism increases insulin secretion.[37] Tirzepatide has been reported to increase levels of adiponectin, an adipokine involved in the regulation of both glucose and lipid metabolism, with a maximum increase of 26% from baseline after 26 weeks, at the 10 mg dosage.[15]
Chemistry
Structure
Tirzepatide is an analog of the human GIP hormone with a C20fatty diacid portion attached, used to optimise the uptake and metabolism of the compound.[34] The fatty-diacid section (eicosanedioic acid) is linked via a glutamic acid and two (2-(2-aminoethoxy)ethoxy)acetic acid units to the side chain of the lysine residue. This arrangement allows for a much longer half-life, extending the time between doses, because of its high affinity to albumin.[38]
Synthesis
The synthesis of tirzepatide was first disclosed in patents filed by Eli Lilly and Company in 2016.[39] This uses standard solid phase peptide synthesis, with an allyloxycarbonylprotecting group on the lysine at position 20 of the linear chain of amino acids, allowing a final set of chemical transformations in which the sidechain amine of that lysine is derivatized with the lipid-containing fragment.
Large-scale manufacturing processes have been reported for this compound.[40]
History
Eli Lilly and Company first applied for a patent for a method of glycemic control using tirzepatide in early 2016.[39] The patent was published late that year. After passing phase III clinical trials, Eli Lilly applied for FDA approval in October 2021, with a priority review voucher.[41]
Following the completion of the SURPASS-2 trial (NCT03987919), the company announced in April 2022 that tirzepatide had successfully met their endpoints in obese and overweight patients without diabetes.[42]
In industry-funded preliminary trials comparing tirzepatide to the existing diabetes medication semaglutide (an injected analogue of the hormone GLP-1), tirzepatide showed minor improvement of reductions (2.01%–2.30% depending on dosage) in glycated hemoglobin tests relative to semaglutide (1.86%).[43] A 10 mg dose has also been shown to be effective in reducing insulin resistance, with a reduction of around 8% from baseline, measured using HOMA2-IR (computed with fasting insulin).[15] Fasting levels of IGF binding proteins such as IGFBP1 and IGFBP2 increased following tirzepatide treatment, increasing insulin sensitivity.[15]
The FDA approved tirzepatide based on evidence from nine clinical trials of 7,769 participants with type 2 diabetes, of which 5,415 received tirzepatide.[44] The trials were conducted at 673 sites in 24 countries, including Argentina, Australia, Brazil, Canada, India, Israel, Japan, Mexico, Russian Federation, South Korea, Taiwan, European Union, and the United States (including Puerto Rico).[44] All nine trials were used to assess its safety and five trials were used to evaluate the efficacy of tirzepatide.[44] The five trials used in the efficacy evaluation included 6,263 adult participants with type 2 diabetes.[44] Four additional trials (NCT03131687, NCT03311724, NCT03861052, NCT03861039) were included in the safety evaluation, for a total of 7,769 adult participants with type 2 diabetes; therefore, the number of participants representing efficacy findings may differ from the number of participants representing safety findings due to different pools of study participants analyzed for efficacy and safety.[44] The benefits of tirzepatide for the treatment of adult participants with type 2 diabetes were primarily evaluated in five clinical trials.[44] In two of these trials (NCT03954834 and NCT04039503), participants were randomly assigned to receive either tirzepatide or placebo injection weekly.[44] Neither the patient nor the healthcare provider knew which treatment was being given until after the trials were completed.[44] Treatment was given for 40 weeks.[44] In the other three trials (NCT3987919, NCT03882970, and NCT03730662), participants were randomly assigned to receive either tirzepatide or another antidiabetic medication, and the patient and provider knew which medication was being given.[44] Treatment was given for 40 weeks to 104 weeks.[44] In each trial, HbA1c was measured from the start of the trial to the end of the trial and compared between the tirzepatide group and the other groups.[44]
The efficacy of tirzepatide for chronic weight management (weight reduction and maintenance) in combination with a reduced-calorie diet and increased physical activity was established in two randomized, double-blind, placebo-controlled trials of adults with obesity or overweight with at least one weight-related condition.[17] These studies measured weight reduction after 72 weeks in a total of 2,519 participants who received either 5 mg, 10 mg, or 15 mg of tirzepatide once weekly and a total of 958 participants who received once-weekly placebo injections.[17] In both trials, after 72 weeks of treatment, participants who received tirzepatide at all three dose levels experienced a statistically significant reduction in body weight compared to those who received placebo, and greater proportions of participants who received tirzepatide achieved at least 5% weight reduction compared to placebo.[17]
In August 2024, the SURMOUNT-1 three-year study (176-week treatment period) revealed that tirzepatide reduced the risk of developing type 2 diabetes by 94% in adults with pre-diabetes and obesity or overweight.[45]
Meta-analysis
A 2021 meta-analysis showed that over one year of clinical use, tirzepatide was superior to dulaglutide, semaglutide, insulin degludec, and insulin glargine in improving blood sugar and obesity.[46]
In a phase III double-blind, randomized, controlled trial supported by Eli Lilly, nondiabetic adults with a body mass index of 30 or more, or 27 or more and at least one weight-related complication, excluding diabetes, were randomized to receive once-weekly, subcutaneous tirzepatide (5 mg, 10 mg, or 15 mg) or placebo. The mean percentage change in weight at week 72 was −15.0% (95% confidence interval [CI], −15.9 to −14.2) with 5-mg weekly doses of tirzepatide, −19.5% (95% CI, −20.4 to −18.5) with 10-mg doses, and −20.9% (95% CI, −21.8 to −19.9) with 15-mg doses. Weight change in the placebo group was −3.1% (95% CI, −4.3 to −1.9).[47][48][49]
Society and culture
Legal status
The US Food and Drug Administration (FDA) granted the application for tirzepatide priority review designation.[14] The FDA approved Mounjaro for use in the United States in 2022.[14]
In July 2022, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Mounjaro, intended for the treatment of type2 diabetes.[50] Tirzepatide was approved for medical use in the European Union in September 2022.[12][51]
In December 2024, the FDA approved tirzepatide (Zepbound) as the first medication to be used in the treatment of moderate to severe obstructive sleep apnea.[18][52][53] The FDA granted the application for tirzepatide (Zepbound) fast track, priority review, and breakthrough therapy designations for the treatment of moderate to severe obstructive sleep apnea.[18] The FDA granted the approval of Zepbound to Eli Lilly and Co.[18]
Shortage
In the United States, if the FDA recognizes a drug shortage, compounding pharmacies are allowed to sell custom-made versions of the drug, if they obtain the active pharmaceutical ingredient from an FDA-approved facility.[54] The FDA declared a shortage of tirzepatide on December 15, 2022. It declared the shortage over on October 2, 2024, though enforcement was delayed until December 29, 2024 after a lawsuit by compounding pharmacies challenged the declaration.[55]
Many web sites started selling tirzepatide during the shortage. The U.S National Association of Boards of Pharmacy said there were tens of thousands of online pharmacies operating out of compliance with state and federal regulations or the association's recommendations, with 95% operating illegally.[56][57]
^ abc"Mounjaro EPAR". European Medicines Agency (EMA). 18 July 2022. Archived from the original on 12 December 2022. Retrieved 2 January 2023. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
^World Health Organization (2019). "International nonproprietary names for pharmaceutical substances (INN): recommended INN: list 81". WHO Drug Information. 33 (1). hdl:10665/330896.
^ abUS patent 9474780, Bokvist BK, Coskun T, Cummins RC, Alsina-Fernandez J, "GIP and GLP-1 co-agonist compounds", issued 2016-10-25, assigned to Eli Lilly and Co
^"Mounjaro: Pending EC decision". European Medicines Agency. 22 July 2022. Archived from the original on 28 July 2022. Retrieved 30 July 2022. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
^NABP operates a search tool to locate properly licensed online pharmacies.
Further reading
Frías JP (November 2020). "Tirzepatide: a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) dual agonist in development for the treatment of type 2 diabetes". Expert Rev Endocrinol Metab. 15 (6): 379–394. doi:10.1080/17446651.2020.1830759. PMID33030356. S2CID222213936.
Clinical trial number NCT04184622 for "A Study of Tirzepatide (LY3298176) in Participants With Obesity or Overweight (SURMOUNT-1)" at ClinicalTrials.gov
Clinical trial number NCT04657003 for "A Study of Tirzepatide (LY3298176) in Participants With Type 2 Diabetes Who Have Obesity or Are Overweight (SURMOUNT-2)" at ClinicalTrials.gov
Clinical trial number NCT04657016 for "A Study of Tirzepatide (LY3298176) In Participants After A Lifestyle Weight Loss Program (SURMOUNT-3)" at ClinicalTrials.gov
Clinical trial number NCT04660643 for "A Study of Tirzepatide (LY3298176) in Participants With Obesity or Overweight for the Maintenance of Weight Loss (SURMOUNT-4)" at ClinicalTrials.gov
Clinical trial number NCT05412004 for "Obstructive Sleep Apnea Master Protocol GPIF: A Study of Tirzepatide (LY3298176) in Participants With Obstructive Sleep Apnea (SURMOUNT-OSA)" at ClinicalTrials.gov