Nurses Compass
Drug Guide
Sitagliptin Phosphate and Metformin Hydrochloride
Classification
Therapeutic: Antidiabetic agent, combination; Oral hypoglycemic agent
Pharmacological: Dipeptidyl peptidase-4 (DPP-4) inhibitor and Biguanide
FDA Approved Indications
- Type 2 diabetes mellitus, as an adjunct to diet and exercise to improve glycemic control
Mechanism of Action
Sitagliptin inhibits DPP-4 enzyme, increasing incretin levels which stimulate insulin release and decrease glucagon levels in a glucose-dependent manner. Metformin decreases hepatic glucose production, increases insulin sensitivity, and enhances peripheral glucose uptake.
Dosage and Administration
Adult: Typically, one tablet twice daily with meals, dosage based on renal function and tolerability.
Pediatric: Not approved for use in pediatric patients.
Geriatric: Adjustments may be necessary based on renal function; initial lower doses recommended.
Renal Impairment: Dose adjustment required; contraindicated in severe impairment.
Hepatic Impairment: Use with caution; contraindicated in severe hepatic disease.
Pharmacokinetics
Absorption: Both drugs are well absorbed, with metformin absorption being incomplete.
Distribution: Metformin distributes into tissues; sitagliptin is mainly in plasma.
Metabolism: Metformin is not metabolized; sitagliptin undergoes minimal metabolism.
Excretion: Primarily excreted unchanged in urine; renal function impacts clearance.
Half Life: Approximately 12 hours for sitagliptin; about 17.6 hours for metformin.
Contraindications
- Renal impairment (eGFR below 45 mL/min/1.73m²),
- Metabolic acidosis, including diabetic ketoacidosis
Precautions
- Monitor renal function regularly, risk of lactic acidosis with metformin, potential for hypoglycemia when combined with other agents.
Adverse Reactions - Common
- Hypoglycemia (Less common with monotherapy)
- Gastrointestinal upset (nausea, diarrhea) (Common in initial treatment)
Adverse Reactions - Serious
- Lactic acidosis (Rare but serious)
- Pancreatitis (Rare)
Drug-Drug Interactions
- Insulin and other secretagogues (hypoglycemia risk)
- Cationic drugs affecting renal function
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood glucose and renal function regularly.
Diagnoses:
- Risk for unstable blood glucose levels
- Risk for lactic acidosis
Implementation: Administer with meals to reduce gastrointestinal side effects.
Evaluation: Assess blood glucose control and renal function periodically.
Patient/Family Teaching
- Take medication as prescribed, especially with meals.
- Report symptoms of hypoglycemia, lactic acidosis, or pancreatitis.
- Maintain regular blood glucose and renal function monitoring.
Special Considerations
Black Box Warnings:
- Lactic acidosis risk with metformin, especially in renal impairment.
Genetic Factors: Not specifically related to genetic factors.
Lab Test Interference: May interfere with serum lactate and blood glucose tests.
Overdose Management
Signs/Symptoms: Severe hypoglycemia, lactic acidosis (metformin overdose).
Treatment: Discontinue medication; supportive care; consider hemodialysis for metformin toxicity.
Storage and Handling
Storage: Store at room temperature, away from moisture and heat.
Stability: Stable under recommended storage conditions.