ZEPBOUND (AUTOINJECTOR)
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZEPBOUND (AUTOINJECTOR) (ZEPBOUND (AUTOINJECTOR)).
Tirzepatide is a dual agonist of GLP-1 and GIP receptors, enhancing insulin secretion, delaying gastric emptying, and reducing appetite and food intake.
| Metabolism | Metabolized via proteolytic cleavage of the peptide backbone, with some involvement of peptidases and possibly CYP enzymes (minor). Excreted primarily as metabolites in urine and feces. |
| Excretion | Primarily renal excretion of intact tirzepatide (approximately 50-60% of the dose) and minor biliary/fecal excretion (<10%). The remainder is metabolized via proteolysis into small peptides and amino acids. |
| Half-life | Terminal elimination half-life is approximately 5 days (range 4-6 days) following subcutaneous administration, supporting once-weekly dosing. Steady-state is achieved after 4 weeks of weekly dosing. |
| Protein binding | Highly bound to albumin (approximately 99%). |
| Volume of Distribution | Central volume of distribution (Vc) is approximately 4.2 L (0.06 L/kg for a 70 kg individual), indicating limited tissue distribution and primarily confinement to the vascular space. |
| Bioavailability | Subcutaneous: Absolute bioavailability is approximately 80% (range 70-90%) relative to intravenous administration. Oral bioavailability is negligible (<1%) due to peptide degradation and poor permeability. |
| Onset of Action | Subcutaneous: Onset of glucose-lowering effects is observed within 1-2 hours, with maximal effects on postprandial glucose at 4-6 hours. Weight loss effects are gradual, typically evident within 2-4 weeks. |
| Duration of Action | Duration of action is approximately 7 days, consistent with once-weekly dosing. Pharmacodynamic effects on glucose and body weight persist for at least 7 days after the last dose, with gradual return to baseline over several weeks. |
| Molecular Weight | 5182 |
Subcutaneous injection once weekly. Initial dose 2.5 mg; after 4 weeks increase to 5 mg. Continue 5 mg for at least 4 weeks; if additional glycemic control needed, increase in 2.5 mg increments at 4-week intervals to a maximum dose of 15 mg once weekly.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR ≥15 mL/min/1.73 m²). Not recommended in end-stage renal disease (eGFR <15 mL/min/1.73 m²) due to lack of data. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh class A and B). Not studied in severe hepatic impairment (Child-Pugh class C); use with caution. |
| Pediatric use | Safety and efficacy not established in pediatric patients (<18 years). No dosing recommendations available. |
| Geriatric use | No dose adjustment required solely based on age. Consider renal function and potential for increased sensitivity; initiate at lowest dose and titrate cautiously. |
| 1st trimester | Avoid use in the first trimester due to risk of fetal harm; based on animal studies showing embryo-fetal toxicity and potential for teratogenicity. |
| 2nd trimester | Avoid use in the second trimester; limited human data, but animal studies show fetal toxicity and risk of preterm birth. |
| 3rd trimester | Avoid use in the third trimester; may cause fetal hypoglycemia and growth restriction; use only if maternal benefit outweighs risk. |
Clinical note
Comprehensive clinical and safety monograph for ZEPBOUND (AUTOINJECTOR) (ZEPBOUND (AUTOINJECTOR)).
| Placental transfer | Tirzepatide is a large peptide (MW ~5182 Da) and is expected to cross the placenta in limited amounts, but animal studies suggest transfer and fetal exposure. Human data insufficient. |
| Breastfeeding | Not recommended during breastfeeding. Zepbound (tirzepatide) is a GIP/GLP-1 receptor agonist; unknown if excreted in human milk, but due to high molecular weight and potential for GI adverse effects in infant, advise against use. |
■ FDA Black Box Warning
Risk of thyroid C-cell tumors. Tirzepatide 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).
| Serious Effects |
History of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2)Known hypersensitivity to tirzepatide or any componentSevere gastrointestinal disease (e.g., gastroparesis)
| Precautions | Pancreatitis: Discontinue if suspected; avoid if history of pancreatitis., Hypoglycemia: Monitor blood glucose, especially when used with insulin or insulin secretagogues., Acute kidney injury: Monitor renal function in patients with renal impairment., Gastrointestinal effects: May cause nausea, vomiting, diarrhea; adjust dose as needed., Hypersensitivity reactions: Discontinue if anaphylaxis or angioedema occurs., Diabetic retinopathy: Monitor for worsening in patients with history of retinopathy. |
| Food/Dietary | No specific food restrictions are required with ZEPBOUND. However, patients are advised to follow a reduced-calorie diet and increased physical activity as part of a comprehensive weight management plan. Because tirzepatide delays gastric emptying, high-fat meals may exacerbate gastrointestinal adverse effects such as nausea and vomiting. Patients should be counseled to eat smaller, more frequent meals and avoid greasy or spicy foods to improve tolerability. Alcohol consumption may increase the risk of hypoglycemia when used with insulin or insulin secretagogues; moderate intake is advised. |
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| Lactation Rating | L5 |
| Teratogenic Risk | Tirzepatide (Zepbound) is a GLP-1/GIP receptor agonist. Based on animal studies, there is a risk of fetal harm. Limited human data; advise avoiding in pregnancy. First trimester: potential for malformations. Second/third trimester: risk of fetal growth abnormalities and neonatal hypoglycemia if used near term. |
| Fetal Monitoring | Monitor maternal weight, blood glucose, and fetal growth via ultrasound. Assess for neonatal hypoglycemia post-delivery if exposure in third trimester. |
| Fertility Effects | In animal studies, tirzepatide caused delayed estrus and reduced fertility at high doses. Human fertility impact unknown; may improve fertility in women with PCOS due to weight loss, but avoid during pregnancy. |
| Clinical Pearls | ZEPBOUND (tirzepatide) is a GIP/GLP-1 receptor agonist approved for chronic weight management. Administer subcutaneously once weekly, rotating injection sites (abdomen, thigh, upper arm). Dose titration is required: start at 2.5 mg weekly for 4 weeks, then increase to 5 mg. Further increments of 2.5 mg every 4 weeks as tolerated, up to 15 mg. Monitor for gastrointestinal adverse effects (nausea, vomiting, diarrhea), which are most common during dose escalation. Contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN-2). Assess for pancreatitis: discontinue if suspected. May cause acute gallbladder disease; monitor for cholelithiasis. No dedicated studies in renal or hepatic impairment; use caution. Concomitant use with insulin secretagogues (e.g., sulfonylureas) increases hypoglycemia risk; consider reducing dose of secretagogue. |
| Patient Advice | Inject ZEPBOUND once weekly on the same day each week, with or without meals. · Store unused autoinjectors in the refrigerator (36°F to 46°F); can be stored at room temperature (up to 86°F) for up to 21 days. · Do not share your autoinjector with others, even if the needle has been changed. · Common side effects include nausea, vomiting, diarrhea, decreased appetite, and constipation; these often lessen over time. · Drink plenty of fluids to prevent dehydration if you experience vomiting or diarrhea. · Report symptoms of pancreatitis: severe abdominal pain that may radiate to the back, with or without vomiting. · Seek medical attention immediately for signs of allergic reaction: hives, difficulty breathing, swelling of face, lips, tongue, or throat. · Tell your doctor if you have a history of thyroid tumors or if you develop a lump in the neck, hoarseness, or trouble swallowing. · Do not use if you are pregnant, planning to become pregnant, or breastfeeding; use effective contraception during treatment. · If you miss a dose, take it within 4 days of the missed dose. If more than 4 days have passed, skip the missed dose and resume your regular schedule. |