MOUNJARO (AUTOINJECTOR)
Clinical safety rating
cautionComprehensive clinical and safety monograph for MOUNJARO (AUTOINJECTOR) (MOUNJARO (AUTOINJECTOR)).
Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. It increases glucose-dependent insulin secretion, decreases glucagon secretion, slows gastric emptying, and promotes satiety.
| Metabolism | Metabolized by proteolytic cleavage of the peptide backbone, followed by beta-oxidation of the fatty diacid moiety and amide hydrolysis. CYP enzymes and esterases are not involved. |
| Excretion | Renal: negligible; Fecal: primarily via biliary elimination as intact peptide; total clearance ~0.056 L/h. |
| Half-life | Terminal elimination half-life ~5 days (117 hours), supporting once-weekly dosing. |
| Protein binding | ~99% bound to albumin. |
| Volume of Distribution | 3.3 L (not weight-based), indicating limited tissue distribution. |
| Bioavailability | Subcutaneous: ~75–80%. |
| Onset of Action | Subcutaneous: glycemic effects observed within 2–4 weeks; maximal glucose lowering by 8–12 weeks. |
| Duration of Action | Subcutaneous: pharmacodynamic effects persist for at least 1 week; steady-state achieved after 4 weeks. |
| Molecular Weight | 4115.2 |
| Action Class | Dual GIP/GLP-1 Receptor Agonist |
Subcutaneously once weekly; initial dose 2.5 mg for 4 weeks, then increase to 5 mg for 4 weeks, then 7.5 mg, 10 mg, 12.5 mg, and 15 mg as tolerated; maximum 15 mg weekly.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR 30-89 mL/min/1.73 m²). Not recommended for use in patients with severe renal impairment (eGFR <30 mL/min/1.73 m²) or end-stage renal disease. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A). Not recommended for use in moderate to severe hepatic impairment (Child-Pugh B or C). |
| Pediatric use | Safety and efficacy not established in pediatric patients under 18 years of age. |
| Geriatric use | No dose adjustment recommended based on age alone; consider renal function as older patients may have reduced renal function. |
| 1st trimester | Contraindicated due to potential for fetal harm; animal studies show adverse effects at exposures below human clinical exposure. |
| 2nd trimester | Contraindicated; limited human data, but animal studies suggest risk of fetal malformations and growth retardation. |
| 3rd trimester | Contraindicated; poses risk of fetal abnormalities and potential for neonatal hypoglycemia. |
Clinical note
Comprehensive clinical and safety monograph for MOUNJARO (AUTOINJECTOR) (MOUNJARO (AUTOINJECTOR)).
| Placental transfer | Expected to cross placenta due to molecular size; animal studies demonstrate transfer. |
| Breastfeeding | No information available on presence in human milk; caution advised as systemic absorption in infant is possible. Weigh benefits vs risks. |
| Lactation Rating | L4 |
| Teratogenic Risk | First trimester: No adequate human data; animal studies show fetal harm at clinically relevant exposures. Second and third trimesters: Potential for fetal harm due to maternal weight loss and metabolic changes; avoid use as pregnancy advances. |
| Fetal Monitoring | Monitor maternal weight, blood glucose, and for gastrointestinal adverse effects. Fetal growth and amniotic fluid assessment recommended due to potential for maternal metabolic changes. |
| Fertility Effects | Animal studies show reduced fertility in females at high doses; human data lacking. May impair fertility due to weight loss and hormonal changes. Discontinue if pregnancy is planned. |
■ FDA Black Box Warning
WARNING: RISK OF THYROID C-CELL TUMORS. Tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors in rats. It is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
| Common Effects | Nausea, Vomiting, Diarrhea, Decreased appetite, Constipation, Dyspepsia, Abdominal pain, Fatigue, Injection site reactions |
| Serious Effects | Pancreatitis (acute or chronic), Medullary thyroid carcinoma (C-cell tumors, seen in animal studies; contraindicated in patients with personal or family history of MTC or MEN-2), Severe hypoglycemia (especially when used with insulin or sulfonylureas), Acute kidney injury (often due to volume depletion), Diabetic retinopathy complications (rapid improvement in glycemic control may worsen retinopathy), Hypersensitivity reactions (angioedema, anaphylaxis), Cholelithiasis and cholecystitis, Suicidal behavior or ideation (rare) |
Hypersensitivity to tirzepatide or any excipientsPersonal or family history of medullary thyroid carcinoma (MTC)Multiple endocrine neoplasia syndrome type 2 (MEN-2)
| Precautions | Risk of thyroid C-cell tumors, Acute pancreatitis, Hypoglycemia (especially with insulin secretagogues or insulin), Hypersensitivity reactions, Acute kidney injury, Severe gastrointestinal disease, Diabetic retinopathy complications, Cholelithiasis and cholecystitis, Suicidal behavior or ideation |
| Food/Dietary | No specific food restrictions required. However, delayed gastric emptying may affect absorption of oral medications; take other oral drugs at least 1 hour before tirzepatide injection. Avoid high-fat meals if experiencing significant nausea or vomiting. |
| Clinical Pearls | Administer subcutaneously in abdomen, thigh, or upper arm; rotate injection sites to avoid lipodystrophy. Do not co-administer with other GLP-1 receptor agonists. Monitor for pancreatitis, diabetic retinopathy complications, and thyroid C-cell tumors. Dose titration required: start at 2.5 mg weekly for 4 weeks, then increase to 5 mg. Max dose 15 mg weekly. Evaluate renal function before initiation; caution in severe renal impairment (eGFR <15 mL/min/1.73 m²). |
| Patient Advice | Inject once weekly on the same day each week, with or without meals. · Store unused autoinjectors in refrigerator at 2-8°C (36-46°F); do not freeze. After first use, can be stored at room temperature up to 30°C (86°F) for up to 21 days. · If a dose is missed and within 4 days, administer as soon as possible; then resume normal schedule. If >4 days, skip missed dose and continue with next scheduled dose. · Common side effects include nausea, vomiting, diarrhea, decreased appetite, and constipation; these may decrease over time. Seek medical attention for severe abdominal pain, vision changes, or signs of allergic reaction. · Avoid using with alcohol, which can increase risk of hypoglycemia especially when combined with sulfonylureas or insulin. · Inform healthcare provider if pregnant, breastfeeding, or planning to become pregnant; discontinue at least 2 months before planned pregnancy due to long half-life. |
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