GLUCOVANCE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for GLUCOVANCE (GLUCOVANCE).
GLUCOVANCE (glyburide/metformin) combines a sulfonylurea (glyburide) that stimulates insulin secretion from pancreatic beta cells by inhibiting ATP-sensitive potassium channels, and a biguanide (metformin) that decreases hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
| Metabolism | Glyburide is extensively metabolized in the liver via CYP2C9 to several inactive metabolites. Metformin is not metabolized; it is excreted unchanged in urine. |
| Excretion | Renal: ~90% (metformin, unchanged, via tubular secretion); Fecal: ~5% (glyburide metabolites); Biliary: minor (<5% for both). |
| Half-life | Metformin: plasma terminal half-life ~6.2 h (renal impairment prolongs); Glyburide: half-life ~10 h (range 7–20 h, prolonged in hepatic impairment). |
| Protein binding | Metformin: negligible (<5%); Glyburide: 99% (primarily to albumin). |
| Volume of Distribution | Metformin: 1.0 L/kg (distributes into erythrocytes and tissues); Glyburide: 0.3 L/kg (limited extravascular distribution). |
| Bioavailability | Metformin: absolute oral bioavailability 50-60% (decreased with food); Glyburide: oral bioavailability ≈100% (but variable absorption). |
| Onset of Action | Oral: glyburide component onset 30-60 min; metformin component onset 2-3 h for glucose-lowering. |
| Duration of Action | Glyburide: 12-24 h (fasting glucose lowering); Metformin: 8-12 h (glycemic control); maximal effect up to 48 h. |
Initial: 1.25 mg glyburide/250 mg metformin once daily. Titrate gradually up to 10 mg glyburide/2000 mg metformin daily based on glycemic response. Administered orally with meals.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if eGFR < 30 mL/min/1.73 m². Not recommended if eGFR 30-45 mL/min/1.73 m². If eGFR 45-60 mL/min/1.73 m², reduce metformin dose and monitor renal function. |
| Liver impairment | Contraindicated in Child-Pugh Class C. Use with caution and reduce dose in mild to moderate hepatic impairment; avoid if severe hepatic impairment. |
| Pediatric use | Not recommended for pediatric patients due to lack of safety and efficacy data. |
| Geriatric use | Initiate at lowest dose (1.25 mg glyburide/250 mg metformin daily) to avoid hypoglycemia. Monitor renal function; do not use if eGFR < 45 mL/min/1.73 m². |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for GLUCOVANCE (GLUCOVANCE).
| Breastfeeding | Both agents are excreted in breast milk. Glyburide: M/P ratio unknown; low levels expected. Metformin: M/P ratio ~0.35; infant dose ~0.5-1% of maternal weight-adjusted dose. Monitor infant for hypoglycemia. Use caution; breastfeeding only if clearly needed. |
| Teratogenic Risk | GLUCOVANCE (glyburide/metformin) is FDA Pregnancy Category C for glyburide and Category B for metformin. Limited human data: glyburide does not cross placenta significantly; metformin crosses placenta. First trimester: insufficient data to rule out risk; use only if benefit outweighs risk. Second/third trimester: associated with increased perinatal morbidity (neonatal hypoglycemia, macrosomia) if maternal glycemic control is poor. Avoid use in pregnancy; insulin preferred. |
■ FDA Black Box Warning
Lactic acidosis: Metformin accumulation can cause lactic acidosis, a rare but serious metabolic complication. Risk factors include renal impairment, concomitant use of certain drugs (e.g., topiramate), age >65 years, radiological studies with contrast, surgery, hypoxic states, excessive alcohol intake, and hepatic impairment. Discontinue metformin promptly 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 lactic acidosis with metformin","Known hypersensitivity to glyburide, metformin, or sulfonylureas","Hepatic impairment","Acute alcohol intoxication or alcoholism","During radiological studies with iodinated contrast (discontinue temporarily)"]
| Precautions | ["Lactic acidosis (see black box warning)","Hypoglycemia: Monitor glucose; adjust dose for renal impairment, elderly, or debilitated patients.","Hepatic effects: Rare reports of hepatic dysfunction including jaundice and hepatitis.","Cardiovascular mortality: Sulfonylureas may be associated with increased cardiovascular mortality (per UGDP study).","Macrovascular outcomes: No conclusive evidence of macrovascular risk reduction.","Vitamin B12 deficiency: Metformin can decrease vitamin B12 levels; monitor annually.","Acute kidney injury: Discontinue if renal impairment develops.","Hypersensitivity reactions: e.g., angioedema, Stevens-Johnson syndrome."] |
Loading safety data…
| Fetal Monitoring | Monitor maternal blood glucose and HbA1c. Fetal: ultrasound for growth and anomalies, nonstress test, biophysical profile, and amniotic fluid index in third trimester. Neonatal: monitor for hypoglycemia, respiratory distress, and electrolyte abnormalities. |
| Fertility Effects | No direct evidence of impaired fertility in humans. Metformin may improve ovulation in women with PCOS. Glyburide does not affect fertility. Both are pregnancy category C/B; effects on fertility reversible upon discontinuation. |