ZITUVIMET XR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZITUVIMET XR (ZITUVIMET XR).
Zituvimet XR (sitagliptin/metformin) is a combination of a dipeptidyl peptidase-4 (DPP-4) inhibitor (sitagliptin) and a biguanide (metformin). Sitagliptin increases incretin levels (GLP-1, GIP), enhancing insulin secretion and decreasing glucagon secretion. Metformin 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; metabolism is minor via CYP3A4 and CYP2C8. Metformin: not metabolized; excreted unchanged in urine via tubular secretion. |
| Excretion | Renal: sitagliptin ~79% unchanged in urine; metformin ~90% unchanged in urine via tubular secretion. Biliary/fecal: minimal. |
| Half-life | Sitagliptin: 12.4 h (prolonged in renal impairment); metformin: 6.2 h (prolonged in renal impairment). Clinically, twice-daily dosing for immediate-release, but ZITUVIMET XR is once-daily. |
| Protein binding | Sitagliptin: 38% bound (mainly albumin); metformin: negligible (<5% bound). |
| Volume of Distribution | Sitagliptin: 0.4 L/kg; metformin: 1.1 L/kg (high, indicating extensive tissue distribution; metformin accumulates in erythrocytes and GI tract). |
| Bioavailability | Sitagliptin: 87% (oral); metformin: ~55% (oral, decreased in extended-release vs immediate-release, with plasma Cmax delayed). |
| Onset of Action | Oral: sitagliptin DPP-4 inhibition within 1-2 h; metformin glucose-lowering within 2-3 h (single dose). |
| Duration of Action | Sitagliptin: 24 h (once-daily dosing); metformin: ~24 h (extended-release formulation provides sustained glucose lowering). Clinical note: effect persists beyond half-life due to mechanism. |
Initial: 1000 mg (2 tablets) orally once daily with the evening meal. Titrate based on efficacy and tolerability. Maximum daily dose: 2000 mg (4 tablets).
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | eGFR 30-59 mL/min: Maximum dose 1000 mg daily; eGFR <30 mL/min or dialysis: Contraindicated. |
| Liver impairment | No specific adjustment recommended; use with caution in severe hepatic impairment (Child-Pugh class C) due to limited data. |
| Pediatric use | Safety and efficacy not established in pediatric patients <18 years. |
| Geriatric use | Initiate at low end of dosing range due to age-related renal impairment; monitor renal function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZITUVIMET XR (ZITUVIMET XR).
| Breastfeeding | Metformin: excreted into breast milk, M/P ratio ~0.35, infant dose ~0.5% maternal weight-adjusted dose, considered compatible with breastfeeding. Sitagliptin: unknown if excreted in human milk; caution advised. |
| Teratogenic Risk | ZITUVIMET XR (sitagliptin/metformin extended-release) is contraindicated in the second and third trimesters due to metformin-associated lactic acidosis risk; limited human data for sitagliptin suggest low teratogenic risk. First trimester exposure: No evidence of major malformations in animal studies, but human data insufficient. |
■ FDA Black Box Warning
Lactic acidosis: Metformin-associated lactic acidosis (MALA) is a rare but serious complication. Risk factors include renal impairment, concomitant use of certain drugs (e.g., topiramate, acetazolamide), age ≥65 years, radiological studies with contrast, surgery, acute conditions (e.g., dehydration, severe infection), hepatic impairment, and alcohol intake. Discontinue metformin if lactic acidosis is suspected.
| Serious Effects |
["Severe renal impairment: eGFR <30 mL/min/1.73 m²","Acute or chronic metabolic acidosis, including diabetic ketoacidosis","History of serious hypersensitivity reaction to sitagliptin or metformin"]
| Precautions | ["Lactic acidosis risk (see black box warning)","Renal impairment: contraindicated if eGFR <30 mL/min/1.73 m²; not recommended if eGFR 30-45; assess renal function before initiation and periodically","Hypoglycemia: when used with insulin or insulin secretagogues","Pancreatitis: acute pancreatitis reported; discontinue if suspected","Heart failure: sitagliptin associated with heart failure risk; monitor","Hypersensitivity reactions: including Stevens-Johnson syndrome","Vitamin B12 deficiency: metformin may decrease B12 levels","Acute alcohol intoxication: warn against excessive alcohol intake","Iodinated contrast: discontinue metformin prior to or at time of imaging; restart after 48 hours if renal function stable"] |
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| Fetal Monitoring |
| Monitor maternal renal function, blood glucose, and lactic acid levels. Assess fetal growth and amniotic fluid volume via serial ultrasound. Monitor for neonatal hypoglycemia if used near term. |
| Fertility Effects | Metformin may improve ovulatory function in women with polycystic ovary syndrome (PCOS), potentially enhancing fertility. Sitagliptin has no known adverse effects on fertility. |