JANUMET 50/1000/MG FC TAB 56/FC TAB

Indications

Approved Uses

Adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus when treatment with both sitagliptin and metformin is appropriate.

Dosage & Administration

Dosing by Condition

Type 2 diabetes mellitus: individualize based on current therapy; for IR JANUMET, usual regimen is twice daily with meals, not exceeding sitagliptin 100 mg/day and metformin 2000 mg/day; switch patients already on both components to the nearest equivalent combination dose.

Initial Dose

For patients not currently treated with metformin: 50 mg sitagliptin/500 mg metformin hydrochloride twice daily. For patients already on metformin: 50 mg sitagliptin twice daily plus the current dose of metformin.

Maintenance Dose

50 mg sitagliptin/500 mg metformin or 50 mg sitagliptin/1000 mg metformin twice daily.

Maximum Dose

Sitagliptin 100mg/day + Metformin 2000mg/day (i.e., one 50mg/1000mg tablet twice daily)

Children's Dosage

Not approved for use in children under 18 years.

Dose Adjustment Notes

Titrate the metformin component gradually to improve GI tolerability; assess renal function before initiation and periodically-do not use if eGFR <30 mL/min/1.73 m², and initiation is generally not recommended if eGFR 30-45; if eGFR falls <45 during therapy, reassess risk/benefit and dose because the fixed-dose combination limits individual component adjustment (sitagliptin otherwise requires renal dose reduction).

How to Take

Take orally with meals (typically twice daily for immediate‑release JANUMET); swallow tablets whole-do not split, crush, or chew.

Side Effects

Common Side Effects

Nausea, diarrhea, vomiting, abdominal pain, flatulence, headache, upper respiratory tract infection, nasopharyngitis, hypoglycemia (when used with insulin or sulfonylurea)

Safety & Warnings

Contraindications

Contraindicated in: severe renal impairment (eGFR <30 mL/min/1.73 m²), acute or chronic metabolic acidosis (including DKA), and history of serious hypersensitivity to sitagliptin or metformin; temporarily withhold around iodinated contrast in at-risk patients (precaution, not a strict contraindication).

Warnings & Precautions

Precautions: lactic acidosis risk-assess renal function before start and periodically; withhold in hypoxia, dehydration, sepsis, acute renal decline, and around iodinated contrast (in at-risk patients) and major surgery; pancreatitis-stop if suspected; hypersensitivity reactions; consider HF risk monitoring; long-term metformin may lower vitamin B12; not for type 1 diabetes or DKA.

Drug Interactions

Drug Interactions

Key interactions: alcohol (↑ lactic acidosis risk), iodinated contrast media (requires temporary withholding in at-risk patients), carbonic anhydrase inhibitors (e.g., topiramate/acetazolamide; ↑ acidosis risk), drugs that reduce renal function (e.g., NSAIDs/ACEi/diuretics; ↑ metformin accumulation risk), cationic drugs affecting metformin clearance (e.g., cimetidine, ranolazine, dolutegravir, trimethoprim), and insulin/sulfonylureas (↑ hypoglycemia risk).

Interaction Severity

MAJOR: iodinated contrast media (temporarily withhold metformin in at‑risk patients to reduce lactic acidosis/AKI risk), excessive alcohol (lactic acidosis risk), carbonic anhydrase inhibitors (e.g., topiramate/acetazolamide; metabolic acidosis risk). MODERATE: insulin/sulfonylureas (hypoglycemia risk), drugs that increase metformin exposure by reducing renal tubular secretion/clearance (e.g., cimetidine, ranolazine, dolutegravir, trimethoprim), and drugs that worsen glycemic control (e.g., corticosteroids, thiazides). MINOR: digoxin (small PK changes reported with sitagliptin).

Food Interaction

Take with food/meals (IR typically with morning and evening meals) to improve GI tolerability; food is not a clinically significant interaction but affects tolerability and (for XR) may affect absorption characteristics.

Alcohol Interaction

Dangerous

Special Populations

Children

Not approved for use in children under 18 years.

Elderly

Use with caution; assess renal function more frequently (at least annually); start at lower metformin doses and titrate carefully; avoid use in patients ≥80 years unless renal function is confirmed to be normal

Kidney Impairment

eGFR ≥45: no adjustment; eGFR 30-<45: Assess risks/benefits of continuing therapy; eGFR <30: contraindicated.

Liver Impairment

Avoid use in patients with hepatic impairment/clinical hepatic disease (no dose adjustment strategy; increased lactic acidosis risk).

Storage & Patient Advice

Stopping the Medicine

Do not stop without clinician advice; temporarily withhold for iodinated contrast procedures (in appropriate risk groups) and during acute illness/situations that may reduce renal function or cause hypoxia/dehydration.

Overdose

Overdose may cause metformin-associated lactic acidosis (nonspecific symptoms such as malaise, myalgias, respiratory distress, abdominal symptoms, hypothermia/hypotension/bradyarrhythmias); management is immediate discontinuation, urgent hospital evaluation/supportive care, and hemodialysis to remove metformin and correct acidosis (treat hypoglycemia if co-administered agents involved).

Patient Counseling

Take JANUMET (sitagliptin/metformin) by mouth with meals (typically twice daily with morning and evening meals) to reduce GI upset; take it consistently and do not stop without prescriber advice. Monitor blood glucose as directed; know hypoglycemia symptoms (sweating, shakiness, confusion), especially if used with insulin or a sulfonylurea. Avoid excessive alcohol and maintain hydration. Seek urgent care for possible lactic acidosis (unusual muscle pain, severe weakness/fatigue, trouble breathing, abdominal pain with nausea/vomiting, feeling cold/dizzy/slow heartbeat). Stop and seek care for severe allergic reaction or severe skin reaction; report severe joint pain. Seek care for pancreatitis symptoms (severe persistent abdominal pain ± vomiting). Tell providers before surgery or iodinated contrast imaging-metformin may need temporary interruption and renal function reassessment.

Monitoring Requirements

Monitor glycemic control (HbA1c about every 3 months until stable then at least twice yearly; SMBG as appropriate), renal function (eGFR/SCr before start and at least annually, more often if at risk), vitamin B12 periodically with long-term metformin, and assess for hypoglycemia when used with insulin/secretagogues; consider LFTs if hepatic disease suspected.

Pharmacology

Mechanism of Action

Sitagliptin inhibits DPP‑4, increasing endogenous incretins (GLP‑1/GIP) to enhance glucose‑dependent insulin release and suppress glucagon; metformin decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity (AMPK-mediated effects).

Onset of Action

Sitagliptin begins inhibiting DPP‑4 within hours of a dose (peak effect around 1-4 hours); metformin’s glucose-lowering effect begins within days, with full HbA1c effect typically over ~4-12 weeks.

Duration of Effect

Sitagliptin provides ~24‑hour DPP‑4 inhibition permitting once‑daily total dosing (100 mg/day), while metformin’s glucose‑lowering effect is maintained over the dosing interval with regular dosing (IR typically BID; XR once daily).

Half-Life

Sitagliptin: approximately 12.4 hours; Metformin: approximately 6.2 hours (plasma), 17.6 hours (blood)

Bioavailability

Sitagliptin: ~87% oral bioavailability; Metformin (immediate-release component): ~50-60% under fasting conditions (decreases with food).

Metabolism

Sitagliptin: minimal metabolism; a small fraction (~16%) metabolized mainly by CYP3A4 and CYP2C8 to inactive metabolites. Metformin: not metabolized (excreted unchanged).

Excretion

Sitagliptin: primarily renal elimination with ~79% excreted unchanged in urine (overall majority via kidney); Metformin: renal elimination, excreted unchanged (approximately 90% recovered in urine within 24 hours).

Protein Binding

Sitagliptin: approximately 38%; Metformin: negligible (<1%)

Product Information

Available Dosage Forms

JANUMET: film‑coated immediate‑release tablet; JANUMET XR: film‑coated extended‑release tablet.

Composition per Dose

Each film-coated tablet: Sitagliptin 50mg (as sitagliptin phosphate monohydrate) + Metformin hydrochloride 1000mg

OTC Alternatives

No OTC alternative

Diabetes Type

Type 2

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