ZITUVIMET
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZITUVIMET (ZITUVIMET).
ZITUVIMET (sitagliptin/metformin) combines sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, which increases incretin levels (GLP-1, GIP), enhancing insulin secretion and decreasing glucagon secretion; and metformin, a biguanide that decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
| Metabolism | Sitagliptin: primarily excreted unchanged in urine (79%), with minor metabolism via CYP3A4 and CYP2C8; Metformin: excreted unchanged in urine, not metabolized. |
| Excretion | Renal: 90% (metformin unchanged), biliary/fecal: 10% (sitagliptin). |
| Half-life | Metformin: ~6.2 hours (prolonged in renal impairment); sitagliptin: ~12.4 hours (allows once-daily dosing). |
| Protein binding | Metformin: negligible (<5%); sitagliptin: 38% (primarily albumin). |
| Volume of Distribution | Metformin: 0.1-0.3 L/kg (low, minimal tissue binding); sitagliptin: 0.4 L/kg (moderate). |
| Bioavailability | Metformin: 50-60% (oral, active absorption); sitagliptin: 87% (oral). |
| Onset of Action | Metformin: Within 2 hours (oral); sitagliptin: Within 1-2 hours (oral). |
| Duration of Action | Metformin: 8-12 hours (glucose-lowering); sitagliptin: ~24 hours (DPP-4 inhibition). |
| Molecular Weight | 321.67 |
Zituvimet is a fixed-dose combination tablet containing sitagliptin 50 mg and metformin hydrochloride 500 mg or 1000 mg. Usual adult dose: one tablet (50 mg sitagliptin / 500 mg metformin) twice daily with meals, or one tablet (50 mg sitagliptin / 1000 mg metformin) twice daily with meals, based on patient's current metformin dose. Maximum daily dose: sitagliptin 100 mg, metformin 2000 mg. Route: oral, with meals to reduce gastrointestinal side effects.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if eGFR <30 mL/min/1.73 m². No dose adjustment needed for eGFR ≥60 mL/min/1.73 m². For eGFR 45-59: maximum metformin dose 1000 mg/day; reduce Zituvimet strength accordingly (e.g., use 50/500 strength twice daily only if patient on sitagliptin 100 mg; otherwise consider separate components). For eGFR 30-44: maximum metformin dose 500 mg twice daily; do not initiate; reassess renal function regularly. Discontinue if eGFR declines persistently below 30. |
| Liver impairment | Avoid use in patients with hepatic impairment (Child-Pugh class B or C) due to metformin component. In mild hepatic impairment (Child-Pugh A), no dose adjustment for sitagliptin; use with caution and monitor lactate levels. Metformin is contraindicated in severe hepatic impairment due to risk of lactic acidosis. |
| Pediatric use | Safety and efficacy not established in pediatric patients under 18 years of age. Not recommended. |
| 1st trimester | Limited data; animal studies show no risk, but no adequate human studies. Use only if potential benefit justifies risk to fetus. |
| 2nd trimester | Data insufficient; avoid unless clearly needed. |
| 3rd trimester | Data insufficient; avoid unless clearly needed. |
Clinical note
Comprehensive clinical and safety monograph for ZITUVIMET (ZITUVIMET).
| Placental transfer | Crosses placenta in animal studies; expected in humans based on molecular weight. |
| Breastfeeding | Excreted in breast milk in animal studies; unknown in humans. Caution advised due to potential hypoglycemia in infant. |
| Lactation Rating |
■ FDA Black Box Warning
WARNING: LACTIC ACIDOSIS. Metformin hydrochloride can cause lactic acidosis, a rare but serious condition that can be fatal. Symptoms include malaise, myalgias, respiratory distress, increasing somnolence, and nonspecific abdominal distress. Risk factors include renal impairment, concomitant use of certain drugs, age >65 years, radiological studies with contrast, surgery, excessive alcohol intake, hepatic impairment, and hypoxic states. Discontinue metformin if lactic acidosis is suspected.
| Serious Effects |
Hypersensitivity to drug or componentsSevere renal impairment (eGFR < 30 mL/min/1.73 m²)Metabolic acidosis (including diabetic ketoacidosis)
| Precautions | Lactic acidosis risk (see boxed warning), Pancreatitis (postmarketing cases; discontinue if suspected), Heart failure (cases with DPP-4 inhibitors; caution in patients with risk factors), Renal impairment (assess renal function before initiation and periodically), Hypoglycemia (risk increased when combined with insulin or sulfonylureas), Vitamin B12 deficiency (monitor with long-term metformin use) |
| Food/Dietary |
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| Geriatric use |
| Use with caution in patients ≥65 years due to increased risk of metformin-associated lactic acidosis and decreased renal function. Assess renal function before initiation and regularly thereafter. Initiate with 50/500 mg twice daily and titrate slowly. Monitor for adverse effects. |
| L3 (Moderately Safe) |
| Teratogenic Risk | ZITUVIMET (sitagliptin/metformin) is Pregnancy Category B. No evidence of teratogenicity in animal studies. First trimester: Limited human data, but metformin not associated with major malformations. Second and third trimesters: Metformin crosses placenta; minimal risk of neonatal hypoglycemia or adverse outcomes. Sitagliptin: No human pregnancy data; in animal studies, no teratogenicity at 30 times human exposure. Overall, risk appears low but insufficient data. |
| Fetal Monitoring | Monitor maternal renal function (creatinine) and glycemic control (HbA1c, glucose). Assess fetal growth via ultrasound every 4-6 weeks in third trimester. Monitor for neonatal hypoglycemia after delivery if metformin used late in pregnancy. |
| Fertility Effects | No adverse effects on fertility reported. Metformin may improve ovulation in women with PCOS. Sitagliptin: No known effect on fertility in animal studies. |
| Avoid alcohol; may increase risk of lactic acidosis. Grapefruit juice may enhance metformin absorption; monitor blood glucose closely. Taking with food reduces metformin GI side effects. No significant food interactions with sitagliptin. |
| Clinical Pearls | Zituvimet is a fixed-dose combination of sitagliptin and metformin. Monitor renal function before initiation and periodically; dose adjustment is needed for eGFR <45 mL/min/1.73m2. Avoid in metabolic acidosis. Can cause acute pancreatitis; discontinue if suspected. Use with caution in heart failure patients due to metformin's lactic acidosis risk. Hold for 48 hours before iodinated contrast procedures and restart after renal function rechecked. |
| Patient Advice | Take with meals to reduce gastrointestinal upset. · Swallow tablets whole; do not crush or chew. · Monitor for symptoms of pancreatitis: severe abdominal pain with or without vomiting. · Report signs of lactic acidosis: unusual muscle pain, trouble breathing, dizziness, slow or irregular heartbeat. · Limit alcohol intake due to increased risk of lactic acidosis. · Maintain adequate hydration to prevent dehydration. |