ACTOPLUS MET XR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACTOPLUS MET XR (ACTOPLUS MET XR).
ACTOPLUS MET XR combines pioglitazone, a thiazolidinedione that improves insulin sensitivity by activating PPAR-γ, and metformin, a biguanide that decreases hepatic glucose production and improves peripheral glucose uptake.
| Metabolism | Pioglitazone is extensively metabolized via hepatic CYP2C8 and CYP3A4. Metformin is excreted unchanged in urine, not metabolized. |
| Excretion | Pioglitazone: predominantly hepatic metabolism, 15-30% excreted in urine as metabolites, ~20% in feces. Metformin: 90% renal excretion unchanged via glomerular filtration and tubular secretion. |
| Half-life | Pioglitazone: terminal half-life 3-7 hours (parent), 16-24 hours (active metabolites); clinical effect sustained due to metabolites. Metformin: terminal half-life 6.2 hours (plasma), elimination prolonged in renal impairment (creatinine clearance <60 mL/min). |
| Protein binding | Pioglitazone: >99% bound to albumin. Metformin: negligible protein binding (<1-5%). |
| Volume of Distribution | Pioglitazone: Vd 0.63 L/kg (tissue distribution). Metformin: Vd 654 ± 358 L (high, >20 L/kg), indicating extensive tissue distribution (e.g., erythrocytes, GI tract). |
| Bioavailability | Pioglitazone: absolute bioavailability 83% (oral). Metformin ER: bioavailability 50-60% relative to immediate-release; food reduces extent of absorption. |
| Onset of Action | Pioglitazone: glycemic effects begin within 2-4 weeks; full effect at 6-12 weeks. Metformin (ER): onset of glucose-lowering within 2-3 days; peak effect by 2-3 weeks. |
| Duration of Action | Pioglitazone: duration up to 24 hours; once-daily dosing sufficient due to active metabolites. Metformin ER: duration approximately 24 hours; once-daily dosing maintains therapeutic concentrations. |
| Molecular Weight | Metformin HCl: 165.62 Da; Pioglitazone HCl: 392.89 Da |
Initial dose: 15 mg pioglitazone/500 mg metformin hydrochloride extended-release orally once daily with evening meal. Titrate based on glycemic response, maximum dose 45 mg pioglitazone/2000 mg metformin hydrochloride extended-release per day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | Contraindicated if eGFR < 30 mL/min/1.73 m2. Not recommended if eGFR between 30-45 mL/min/1.73 m2. Use lowest dose if eGFR > 45 mL/min/1.73 m2 and monitor renal function. |
| Liver impairment | Contraindicated in patients with hepatic impairment (Child-Pugh class A, B, or C) due to risk of lactic acidosis with metformin component. |
| Pediatric use | Not recommended for pediatric patients below 18 years of age; safety and efficacy not established. |
| Geriatric use | Use with caution in patients aged 65 years and older. Start at low dose and titrate slowly due to potential for renal impairment and decreased drug clearance. Monitor renal function frequently. |
| 1st trimester | Avoid; insulin is preferred. Associated with increased risk of fetal malformations (e.g., neural tube defects) due to metformin component. |
| 2nd trimester | Avoid; insufficient data for combination product. Use insulin if glycemic control needed. |
| 3rd trimester | Avoid; may cause neonatal hypoglycemia. Discontinue prior to delivery. |
Clinical note
Comprehensive clinical and safety monograph for ACTOPLUS MET XR (ACTOPLUS MET XR).
| Placental transfer | Both metformin and pioglitazone cross the placenta. Metformin concentrations in fetal blood can reach maternal levels. |
| Breastfeeding | Metformin and pioglitazone are excreted into breast milk in small amounts. Theoretical risk of hypoglycemia in infant. Consider alternatives such as insulin. |
■ FDA Black Box Warning
Pioglitazone may cause or exacerbate congestive heart failure. Not recommended in patients with NYHA Class III or IV heart failure. Discontinue if deterioration in cardiac status occurs.
| Serious Effects |
Hypersensitivity to metformin, pioglitazone, or any componentSevere renal impairment (eGFR < 30 mL/min/1.73 m²)Acute or chronic metabolic acidosis (including diabetic ketoacidosis)Active liver disease or elevated transaminases >2.5x ULNNew York Heart Association (NYHA) Class III/IV heart failure
| Precautions | Risk of lactic acidosis with metformin, Congestive heart failure risk with pioglitazone, Bladder cancer risk with pioglitazone, Hepatotoxicity, Hypoglycemia when used with insulin or sulfonylureas, Macular edema, Bone fractures |
| Food/Dietary | Avoid alcohol consumption due to increased risk of lactic acidosis. Grapefruit and grapefruit juice may alter pioglitazone metabolism; avoid excessive intake. Take with food to minimize GI upset; consistent carbohydrate intake is recommended. |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category C. No adequate studies in pregnant women. In animal studies, metformin and pioglitazone showed no clear teratogenicity at clinically relevant doses. Pioglitazone may cause fetal growth restriction in late gestation due to PPARγ activation. Risk of neonatal hypoglycemia if used near term. Use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal blood glucose and HbA1c. Assess fetal growth by serial ultrasound due to potential macrosomia or growth restriction. Monitor for neonatal hypoglycemia after delivery. Maternal renal function, hepatic enzymes, and signs of fluid retention (edema, heart failure) should be monitored. |
| Fertility Effects | Metformin may improve ovulation in women with PCOS. Pioglitazone may restore ovulation in insulin-resistant patients. No known negative effects on fertility in males; however, animal studies with pioglitazone showed reversible effects on sperm parameters at high doses. Human data on fertility are lacking. |
| Clinical Pearls | ACTOPLUS MET XR is a fixed-dose combination of pioglitazone and metformin extended-release. Monitor liver function before and during therapy; pioglitazone can cause hepatotoxicity. Check renal function before starting metformin; contraindicated if eGFR <30 mL/min/1.73m2. Watch for lactic acidosis, especially in patients with renal impairment, sepsis, or dehydration. Pioglitazone may increase risk of bladder cancer; avoid in patients with history. Titrate dose gradually to GI tolerability. |
| Patient Advice | Take with meals to reduce gastrointestinal side effects. · Swallow tablets whole; do not crush, chew, or split extended-release tablets. · Report symptoms of lactic acidosis (muscle pain, trouble breathing, stomach upset, dizziness) or liver problems (yellowing eyes/skin, dark urine). · Monitor for signs of bladder cancer (blood in urine, painful urination). · Notify doctor if you become pregnant or plan to become pregnant. · Avoid alcohol; can increase risk of lactic acidosis. · Regular blood glucose and A1C monitoring is essential. |