REPAGLINIDE AND METFORMIN HYDROCHLORIDE
Clinical safety rating: safe
Alcohol and contrast dye can increase risk of lactic acidosis Can cause lactic acidosis a rare but serious metabolic complication.
Repaglinide stimulates insulin secretion from pancreatic beta cells by closing ATP-sensitive potassium channels, leading to membrane depolarization and calcium influx. Metformin decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
| Metabolism | Repaglinide: Primarily metabolized by CYP2C8 and CYP3A4. Metformin: Not metabolized; excreted unchanged in urine. |
| Excretion | Repaglinide: 90% biliary (feces), 8% renal; Metformin: 90% renal (unchanged), 10% fecal. |
| Half-life | Repaglinide: 1 hour (terminal); Metformin: 6.2 hours (terminal, range 4-9 hours). |
| Protein binding | Repaglinide: >98% bound primarily to albumin; Metformin: negligible (<5%) bound to plasma proteins. |
| Volume of Distribution | Repaglinide: 31 L (approx 0.44 L/kg); Metformin: 654 ± 358 L (approx 9.3 L/kg). |
| Bioavailability | Repaglinide: 63% (oral); Metformin: 50-60% (oral). |
| Onset of Action | Oral: 15-30 minutes for both components. |
| Duration of Action | Repaglinide: 4-6 hours (prandial glucose regulator); Metformin: 12-24 hours (therapeutic effect). |
| Molecular Weight | Repaglinide: 452.59 Da; Metformin: 165.62 Da; Combination not applicable. |
Oral: 1 mg repaglinide/500 mg metformin twice daily, taken within 30 minutes of meals; titrate gradually up to a maximum of 4 mg repaglinide/2000 mg metformin per day in divided doses.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if eGFR <30 mL/min/1.73 m². For eGFR 30-45 mL/min/1.73 m², maximum metformin dose is 1000 mg/day; use lower repaglinide doses with caution. Initiation not recommended if eGFR <45 mL/min/1.73 m². |
| Liver impairment | Contraindicated in Child-Pugh Class B or C hepatic impairment. Use with caution in mild impairment (Child-Pugh A) with reduced doses of both components. |
| Pediatric use | Not established for use in pediatric patients under 18 years of age. |
| Geriatric use | Start at lowest dose (e.g., 0.5 mg repaglinide/250 mg metformin) due to increased risk of hypoglycemia and renal impairment; titrate slowly and monitor renal function regularly. |
| 1st trimester | Avoid; associated with increased risk of congenital malformations, especially when metformin is used. |
| 2nd trimester | Use only if clearly needed; repaglinide not recommended, metformin may be used if benefits outweigh risks. |
| 3rd trimester | Use only if clearly needed; metformin may increase risk of neonatal hypoglycemia. |
Clinical note
Alcohol and contrast dye can increase risk of lactic acidosis Can cause lactic acidosis a rare but serious metabolic complication.
| FDA category | Human |
| Placental transfer | Both repaglinide and metformin cross the placental barrier; metformin transfer documented, repaglinide likely based on molecular weight. |
| Breastfeeding |
■ FDA Black Box Warning
Metformin: Lactic acidosis risk, particularly in patients with renal impairment, hypoxia, sepsis, or hepatic impairment. Repaglinide: No black box warning.
| Common Effects | Diarrhea |
| Serious Effects |
Diabetic ketoacidosisRenal disease (eGFR < 30 mL/min/1.73m^2)Acute or chronic metabolic acidosisKnown hypersensitivity to repaglinide, metformin, or any excipientHepatic impairment
| Precautions | Lactic acidosis, Hypoglycemia, Cardiovascular mortality (controversial with sulfonylureas), Hepatic impairment, Renal impairment, Vitamin B12 deficiency, Acute alcohol intoxication, Surgery or radiologic studies with iodinated contrast |
| Food/Dietary | Alcohol consumption increases the risk of lactic acidosis and hypoglycemia; limit intake. High-carbohydrate meals may require dose adjustment of repaglinide. Grapefruit juice may increase repaglinide plasma concentrations; avoid concurrent use. Metformin absorption may be reduced by food, but administration with meals improves tolerability. |
Loading safety data…
| Metformin is excreted in breast milk in low amounts, unlikely to cause adverse effects in infant. Repaglinide excretion unknown; theoretical risk of hypoglycemia. Caution advised; monitor infant for hypoglycemia. |
| Lactation Rating | L3 (Moderately Safe) for metformin component; L4 (Possibly Hazardous) for repaglinide due to unknown excretion. |
| Teratogenic Risk | Pregnancy Category C. Repaglinide: limited human data; animal studies show no teratogenicity but fetal toxicity at high doses. Metformin: crosses placenta; some studies suggest increased risk of preeclampsia and perinatal mortality, but no major malformations; risk of neonatal hypoglycemia. First trimester: unknown risk; second/third trimester: possible fetal growth restriction, macrosomia from maternal diabetes; avoid unless benefit outweighs risk. |
| Fetal Monitoring | Maternal: blood glucose, HbA1c, renal function, hepatic function. Fetal: ultrasound for growth and anatomy, fetal echocardiography, nonstress test and biophysical profile in third trimester. Neonatal: monitor for hypoglycemia and hyperbilirubinemia. |
| Fertility Effects | Repaglinide: no known direct effect. Metformin: may improve ovulation in polycystic ovary syndrome; no adverse effects on spermatogenesis. Overall, no known negative impact on fertility. |
| Clinical Pearls | Repaglinide primarily stimulates early-phase insulin secretion; metformin reduces hepatic gluconeogenesis and improves peripheral insulin sensitivity. The combination is particularly useful in patients with postprandial hyperglycemia. Avoid use in patients with renal impairment (eGFR <30 mL/min/1.73 m^2) or hepatic disease. Monitor for hypoglycemia, especially when meals are skipped or delayed, as repaglinide is a short-acting secretagogue. Administer repaglinide within 30 minutes before meals; if a meal is skipped, the dose should be skipped. Metformin may cause lactic acidosis in hypoxic states; discontinue temporarily during surgery or iodinated contrast procedures. |
| Patient Advice | Take repaglinide 15-30 minutes before each main meal; if you skip a meal, skip the dose. · Do not take repaglinide if you are not going to eat. · Metformin should be taken with meals to minimize gastrointestinal upset. · Report symptoms of hypoglycemia (shaking, sweating, confusion) immediately. · Avoid excessive alcohol intake while taking metformin due to risk of lactic acidosis. · Inform your doctor if you experience muscle pain, weakness, or unusual drowsiness. · Regular monitoring of blood glucose and kidney function is required. · Do not drive or operate machinery until you know how this medication affects you. |