AVANDAMET
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AVANDAMET (AVANDAMET).
AVANDAMET combines rosiglitazone, a thiazolidinedione that improves insulin sensitivity by activating peroxisome proliferator-activated receptor gamma (PPARγ), and metformin, a biguanide that decreases hepatic glucose production, reduces intestinal glucose absorption, and improves insulin sensitivity.
| Metabolism | Rosiglitazone is extensively metabolized via N-demethylation and hydroxylation, primarily by CYP2C8 and to a lesser extent CYP2C9. Metformin is excreted unchanged in urine and does not undergo hepatic metabolism. |
| Excretion | Renal (90-95% as unchanged drug for rosiglitazone; metformin is 90% renally eliminated unchanged). Biliary/fecal: minor (<5% for both). |
| Half-life | Rosiglitazone: 3-4 hours (terminal); metformin: 6.2 hours (terminal). No accumulation with normal renal function. |
| Protein binding | Rosiglitazone: 99.8% (primarily albumin); metformin: negligible (<5%). |
| Volume of Distribution | Rosiglitazone: 0.25 L/kg (distributes into tissues); metformin: 0.2-0.5 L/kg (mainly in erythrocytes and tissues). |
| Bioavailability | Oral: Rosiglitazone 99%; metformin 50-60% (fasting). Food decreases metformin absorption. |
| Onset of Action | Oral: Rosiglitazone onset 30 minutes, metformin onset 1-2 hours. Peak glucose-lowering effect 2-4 weeks. |
| Duration of Action | Rosiglitazone: 12-24 hours (dosing twice daily); metformin: 8-12 hours (immediate-release), up to 24 hours (extended-release). Clinical effect persists with regular dosing. |
| Molecular Weight | Rosiglitazone maleate: 473.52 Da; Metformin HCl: 165.62 Da |
Oral, initial dose of rosiglitazone 4 mg/metformin 500 mg twice daily or rosiglitazone 2 mg/metformin 500 mg twice daily; maximum recommended dose rosiglitazone 8 mg/metformin 2000 mg per day.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in patients with eGFR < 30 mL/min/1.73 m²; not recommended when eGFR is between 30-45 mL/min/1.73 m²; reduce metformin dose if eGFR 45-60 mL/min/1.73 m². |
| Liver impairment | Avoid use in patients with Child-Pugh Class B or C hepatic impairment; limited data in Class A; contraindicated with clinical evidence of active liver disease or ALT >2.5x ULN at baseline. |
| Pediatric use | Not approved for pediatric patients below 18 years of age; no established dosing guidelines. |
| Geriatric use | Use with caution in patients >65 years; initiate at lowest possible dose; monitor renal function closely due to age-related decrease in renal function; avoid if eGFR <45 mL/min/1.73 m². |
| 1st trimester | Limited data; rosiglitazone and metformin cross placenta. Rosiglitazone associated with fetal growth restriction in animal studies. Metformin may be continued if indicated for pre-existing diabetes; rosiglitazone generally avoided. |
| 2nd trimester | Avoid rosiglitazone component due to potential adverse fetal effects; metformin may be used if benefits outweigh risks. |
| 3rd trimester | Avoid especially near term; rosiglitazone may cause fetal/neonatal hypoglycemia, fluid retention; metformin associated with neonatal hypoglycemia risk. |
Clinical note
Comprehensive clinical and safety monograph for AVANDAMET (AVANDAMET).
| Placental transfer | Both components cross the placenta. Metformin: significant transfer (maternal-to-fetal ratio ~0.5-1.0). Rosiglitazone: minimal data but expected to cross based on molecular weight and lipid solubility. |
| Breastfeeding | Both rosiglitazone and metformin are excreted into breast milk. Metformin levels are low and generally considered compatible; rosiglitazone safety not established due to limited data. Avoid during breastfeeding unless benefit clearly outweighs risk. Monitor infant for hypoglycemia. |
■ FDA Black Box Warning
WARNING: CONGESTIVE HEART FAILURE. Rosiglitazone may cause or exacerbate congestive heart failure. Use is contraindicated in patients with NYHA Class III or IV heart failure. Monitor for signs and symptoms of heart failure after initiation and dose increases.
| Serious Effects |
NYHA Class III/IV heart failureAcute or chronic metabolic acidosis (including diabetic ketoacidosis)Renal impairment (eGFR <30 mL/min/1.73 m²)Hepatic impairmentKnown hypersensitivity to rosiglitazone, metformin, or excipientsPregnancy (rosiglitazone component)
| Precautions | Congestive heart failure, Fluid retention, Myocardial infarction and ischemic heart disease (increased risk with rosiglitazone based on meta-analyses), Lactic acidosis (metformin component), Hepatotoxicity, Macular edema, Fractures, Ovulation in premenopausal anovulatory women, Hypoglycemia, Vitamin B12 deficiency (metformin) |
| Food/Dietary | Avoid excessive alcohol intake (≥3 drinks/day or binge drinking) due to increased lactic acidosis risk. Take tablets with meals to reduce gastrointestinal side effects from metformin. Rosiglitazone absorption unaffected by food. No specific food restrictions besides alcohol moderation. |
Loading safety data…
| Lactation Rating | L4 (Possibly Hazardous) due to rosiglitazone component |
| Teratogenic Risk | Pregnancy category C. Rosiglitazone: crosses placenta; limited human data; animal studies show fetal harm (reduced fetal weight, delayed ossification) at >4x MRHD. Metformin: crosses placenta; associated with reduced birth weight and potential for neonatal hypoglycemia; risk of lactic acidosis theoretical. Inadvertent exposure in first trimester: no clear increased risk of major malformations. Avoid in second and third trimesters due to potential for fetal acidosis. |
| Fetal Monitoring | Maternal: blood glucose, HbA1c, liver function tests (rosiglitazone), renal function (metformin), signs of lactic acidosis, hypoglycemia. Fetal: ultrasound for growth and development, fetal weight monitoring, assessment for macrosomia or growth restriction. Neonatal: blood glucose monitoring for hypoglycemia, observation for acidosis. |
| Fertility Effects | In females: possible restoration of fertility in anovulatory women due to improved insulin sensitivity; risk of unintended pregnancy. In males: no known adverse effects on spermatogenesis or fertility based on limited data. |
| Clinical Pearls | Avandamet (rosiglitazone/metformin) carries a boxed warning for thiazolidinedione-related cardiovascular risk, including myocardial ischemia. Monitor for lactic acidosis, especially in renal impairment (eGFR <30 mL/min contraindicated). Avoid in NYHA Class III/IV heart failure. Assess liver function before initiating and periodically; contraindicated if transaminases >2.5x ULN. Rosiglitazone may cause macular edema; report vision changes. Metformin alone rarely causes lactic acidosis; combined risk increases with acute renal failure, hypoxemia, or concurrent iodinated contrast use. |
| Patient Advice | Take exactly as prescribed, usually twice daily with meals to reduce stomach upset. · Do not drink excessive alcohol (binge or heavy drinking) while taking this medication; it increases the risk of lactic acidosis. · Watch for symptoms of lactic acidosis: unusual fatigue, weakness, muscle pain, trouble breathing, stomach discomfort with nausea or vomiting, dizziness, or slow/irregular heartbeat. If any occur, stop drug and seek emergency care. · Report any vision changes, including blurred vision or eye pain, promptly because rosiglitazone may worsen fluid retention and cause macular edema. · Notify your doctor if you experience rapid weight gain, shortness of breath, or swelling in your ankles or feet (signs of heart failure). · Avandamet may increase risk of fractures in women; ask your doctor about bone health. · Do not skip meals or exercise excessively without medical advice, as this drug lowers blood sugar and can cause hypoglycemia. · Store at room temperature away from moisture and heat. |