MICRONASE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MICRONASE (MICRONASE).
Stimulates insulin secretion from pancreatic beta cells by binding to sulfonylurea receptor (SUR1) on ATP-sensitive potassium channels, leading to membrane depolarization, calcium influx, and exocytosis of insulin.
| Metabolism | Metabolized primarily by CYP2C9 to metabolites with little or no hypoglycemic activity. |
| Excretion | Renal: approximately 50% as metabolites and unchanged drug; biliary/fecal: approximately 50% as metabolites. |
| Half-life | Terminal elimination half-life: 10 hours (range 7-20); clinical context: duration of action may be prolonged in renal impairment. |
| Protein binding | 95-99% bound, primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily into extracellular fluid. |
| Bioavailability | Oral: essentially complete (≈100%) after absorption. |
| Onset of Action | Oral: 30-60 minutes after a single dose. |
| Duration of Action | 12-24 hours; clinically, may require once or twice daily dosing; extended in renal or hepatic impairment. |
Initial dose: 2.5-5 mg orally once daily with breakfast. Maintenance: 1.25-20 mg daily in single or divided doses. Maximum: 20 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR >50 mL/min: No adjustment. GFR 30-50 mL/min: Start with 2.5 mg daily. GFR <30 mL/min: Contraindicated. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): Use with caution; start at lowest dose. Severe hepatic impairment (Child-Pugh C): Avoid use. |
| Pediatric use | Not approved for use in pediatric patients (safety and efficacy not established). |
| Geriatric use | Initial dose: 1.25-2.5 mg daily. Titrate slowly to avoid hypoglycemia. Monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MICRONASE (MICRONASE).
| Breastfeeding | Glyburide is excreted into breast milk in low amounts; M/P ratio approximately 0.6-0.7. Estimated infant dose <1% of maternal weight-adjusted dose. Considered compatible with breastfeeding by many authorities, but monitor infant for hypoglycemia (especially in preterm or ill infants). |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: potential risk of hypoglycemia, but no definitive evidence of major malformations. Second and third trimesters: increased risk of neonatal hypoglycemia and macrosomia; oral hypoglycemics like glyburide (Micronase) may be used as alternative to insulin, though insulin remains preferred. Limited human data; animal studies show no teratogenicity at clinically relevant doses. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Type 1 diabetes mellitus","Diabetic ketoacidosis","Hypersensitivity to glyburide or sulfonylureas","Concomitant use of bosentan"]
| Precautions | ["Hypoglycemia","Hepatic impairment","Renal impairment","Cardiovascular mortality risk (controversial)","Hemolytic anemia in G6PD deficiency"] |
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| Fetal Monitoring | Maternal: Blood glucose monitoring (fasting and postprandial) to maintain euglycemia; HbA1c every trimester; monitor for hypoglycemia, weight gain, and liver function tests periodically. Fetal: Ultrasound for growth assessment (due to increased risk of macrosomia), nonstress test or biophysical profile in third trimester if indicated (e.g., poor glycemic control, polyhydramnios). Newborn: Monitor for hypoglycemia, hyperbilirubinemia, and hypocalcemia. |
| Fertility Effects | No direct adverse effects on fertility reported. Poor glycemic control in diabetes may impair fertility (e.g., menstrual irregularities, increased miscarriage risk). Achieving euglycemia with Micronase may improve fertility outcomes. |