ZEPBOUND

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ZEPBOUND (ZEPBOUND).

How it works

Tirzepatide is a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor dual agonist. It binds to and activates both GIP and GLP-1 receptors, leading to increased insulin secretion, decreased glucagon secretion, slowed gastric emptying, and increased satiety, resulting in improved glycemic control and weight loss.

What the body does with it

Metabolism	Tirzepatide is metabolized via proteolytic cleavage of the peptide backbone, beta-oxidation of the fatty diacid moiety, and amide hydrolysis. It does not significantly involve CYP450 enzymes. Metabolites are excreted primarily in urine and feces.
Excretion	Renal elimination of intact peptide (urine) and proteolytic degradation (fecal/biliary). Following subcutaneous administration, approximately 70% of the dose is excreted renally as intact tirzepatide and 30% via feces as metabolites.
Half-life	Terminal elimination half-life is approximately 5 days (range 4–6 days), supporting once-weekly dosing. Steady state is achieved after 4 weeks of once-weekly administration.
Protein binding	Tirzepatide is highly bound to albumin (approximately 99%).
Volume of Distribution	Volume of distribution is approximately 10.3 L (0.13 L/kg for a 70 kg individual), indicating limited extravascular distribution, primarily confined to plasma and interstitial fluid.
Bioavailability	Subcutaneous: Absolute bioavailability is approximately 80% following abdominal administration. Bioavailability is similar for injection sites (abdomen, thigh, upper arm).
Onset of Action	Subcutaneous: Onset of glucose lowering occurs within 2–3 hours after first dose, with peak effect on postprandial glucose at 4–6 hours. Weight loss onset is variable but typically observed within 2–4 weeks.
Duration of Action	Duration of glucose-lowering effect extends beyond the dosing interval (≥7 days) due to long half-life. Clinical effects on HbA1c and weight are sustained with continued weekly dosing.

Classification & Brands

Dosing & administration

Subcutaneously once weekly; initial dose 2.5 mg for 4 weeks, then increase to 5 mg; if additional glycemic control needed, may increase in 2.5 mg increments after at least 4 weeks on current dose, up to maximum 15 mg once weekly.

Dosage form	SOLUTION
Renal impairment	No dose adjustment required for mild to moderate renal impairment (eGFR ≥30 mL/min/1.73 m²). Not recommended in 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 class A). Not recommended for moderate or severe hepatic impairment (Child-Pugh class B or C).
Pediatric use	Not approved for use in pediatric patients; safety and efficacy not established.
Geriatric use	No dose adjustment required based on age alone; consider renal function and comorbidities; limited experience in patients aged ≥75 years.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ZEPBOUND (ZEPBOUND).

Breastfeeding	Unknown if tirzepatide is excreted in human milk; animal studies show presence in milk. M/P ratio not available. Due to risk of hypoglycemia and potential adverse effects in breastfed infants, breastfeeding is not recommended during treatment and for at least 4 weeks after last dose.
Teratogenic Risk	Tirzepatide (Zepbound) is contraindicated during pregnancy due to potential fetal harm based on animal studies showing reduced fetal growth and skeletal anomalies. Risk in first trimester: insufficient human data; animal data suggest risk. Second/third trimester: adverse fetal outcomes (e.g., oligohydramnios, fetal death) seen in animal studies. No adequate human studies.

Warnings & precautions

■ FDA Black Box Warning

No FDA boxed warning.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Personal or family history of medullary thyroid carcinoma (MTC)","Multiple endocrine neoplasia syndrome type 2 (MEN 2)","Known hypersensitivity to tirzepatide or any excipients"]

Clinical Precautions

Precautions

["Risk of thyroid C-cell tumors (medullary thyroid carcinoma); contraindicated in patients with a personal or family history of MTC or MEN 2","Acute pancreatitis: discontinue if suspected","Hypoglycemia, especially when used with insulin or sulfonylureas","Renal impairment (acute kidney injury reported, may worsen chronic kidney disease)","Gastrointestinal effects (nausea, vomiting, diarrhea) may lead to dehydration","Diabetic retinopathy complications reported (not established)","Hypersensitivity reactions (angioedema, anaphylaxis)","Accelerated growth of pre-existing gastrointestinal neoplasms (caution in patients with history of GI neoplasms)"]

Clinical Tips & Counseling

Drug interactions

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ZEPBOUND

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ZEPBOUND (ZEPBOUND).

How it works

What the body does with it

Metabolism	Tirzepatide is metabolized via proteolytic cleavage of the peptide backbone, beta-oxidation of the fatty diacid moiety, and amide hydrolysis. It does not significantly involve CYP450 enzymes. Metabolites are excreted primarily in urine and feces.
Excretion	Renal elimination of intact peptide (urine) and proteolytic degradation (fecal/biliary). Following subcutaneous administration, approximately 70% of the dose is excreted renally as intact tirzepatide and 30% via feces as metabolites.
Half-life	Terminal elimination half-life is approximately 5 days (range 4–6 days), supporting once-weekly dosing. Steady state is achieved after 4 weeks of once-weekly administration.
Protein binding	Tirzepatide is highly bound to albumin (approximately 99%).
Volume of Distribution	Volume of distribution is approximately 10.3 L (0.13 L/kg for a 70 kg individual), indicating limited extravascular distribution, primarily confined to plasma and interstitial fluid.
Bioavailability	Subcutaneous: Absolute bioavailability is approximately 80% following abdominal administration. Bioavailability is similar for injection sites (abdomen, thigh, upper arm).
Onset of Action	Subcutaneous: Onset of glucose lowering occurs within 2–3 hours after first dose, with peak effect on postprandial glucose at 4–6 hours. Weight loss onset is variable but typically observed within 2–4 weeks.
Duration of Action	Duration of glucose-lowering effect extends beyond the dosing interval (≥7 days) due to long half-life. Clinical effects on HbA1c and weight are sustained with continued weekly dosing.

Classification & Brands

Dosing & administration

Dosage form	SOLUTION
Renal impairment	No dose adjustment required for mild to moderate renal impairment (eGFR ≥30 mL/min/1.73 m²). Not recommended in 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 class A). Not recommended for moderate or severe hepatic impairment (Child-Pugh class B or C).
Pediatric use	Not approved for use in pediatric patients; safety and efficacy not established.
Geriatric use	No dose adjustment required based on age alone; consider renal function and comorbidities; limited experience in patients aged ≥75 years.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ZEPBOUND (ZEPBOUND).

Breastfeeding	Unknown if tirzepatide is excreted in human milk; animal studies show presence in milk. M/P ratio not available. Due to risk of hypoglycemia and potential adverse effects in breastfed infants, breastfeeding is not recommended during treatment and for at least 4 weeks after last dose.
Teratogenic Risk	Tirzepatide (Zepbound) is contraindicated during pregnancy due to potential fetal harm based on animal studies showing reduced fetal growth and skeletal anomalies. Risk in first trimester: insufficient human data; animal data suggest risk. Second/third trimester: adverse fetal outcomes (e.g., oligohydramnios, fetal death) seen in animal studies. No adequate human studies.

Warnings & precautions

■ FDA Black Box Warning

No FDA boxed warning.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Personal or family history of medullary thyroid carcinoma (MTC)","Multiple endocrine neoplasia syndrome type 2 (MEN 2)","Known hypersensitivity to tirzepatide or any excipients"]