Sitagliptin and Metformin

Hypoglycaemic excluding Insulin · Biguanide/Dipeptidyl peptidase-4 inhibitor

Indications

Treatment of type II diabetes as an adjunct to diet and exercise in patients inadequately controlled on metformin alone or those already receiving sitagliptin and metformin.

Dosage

Adults: Initially, 50 mg/500 mg or 50 mg/1000 mg twice daily based on dose of metformin already being taken. For patients receiving components as separate tab, switch to equivalent dose. Doses of sulfonylurea or insulin may need to be reduced. Max daily dose of sitagliptin, 100 mg. Children: Not recommended.

Adverse Effects

Metformin: GI upset, taste disturbance, rarely lactic acidosis, abnormal liver function tests, hepatitis, skin reactions, reduced B12 absorptions. Sitagliptin: Reports of pancreatitis and serious hypersensitivity reactions, including anaphylaxis and Stevens-Johnson syndrome. Hypoglycaemia, headache, bullous pemphigoid. Monotherapy: Osteoarthritis, pain in extremity, upper RTI. With metformin: GI upset. With a glitazone: Flatulence, peripheral oedema. With insulin: Influenza.

Risk Factor (Pregnancy/Lactation)

Pregnancy: Contraindicated in pregnancy. Lactation: Contraindicated or not recommended. Contraindications: Metformin: Diabetic ketoacidosis or precoma, renal or hepatic impairment. Acute conditions predisposing to renal impairment. Cardiac or respiratory failure, recent MI, alcoholism. Administration of iodinated contrast materials. Discontinue for 48 hours before and after elective surgery. Sitagliptin: Diabetic ketoacidosis. Moderate to severe renal impairment. Precautions: Monitor renal function at least annually (2-4 times a year in elderly and patients with serum creatinine levels at ULN). Discontinue for 48 hours before and after surgery and measure renal function before resuming therapy. Elderly.

Interactions

Metformin: Alcohol, iodinated contrast agents, diuretics, corticosteroids, ACE inhibitors, sympathomimetics, NSAIDs, other hypoglycaemics. Inhibitors of OCT2 (e.g., cimetidine, dolutegravir, ranolazine, trimethoprim). Sitagliptin: Digoxin.

Advice to Patient

Take with meals.

Pharmacokinetics

SITAGLIPTIN: Absorption: Rapid. Metabolism: Hepatic (not extensively metabolized). Bioavailability: Approx. 87%. Half-life elimination: 12.4 hrs. Time to peak, plasma: 1-4 hrs. Excretion: Urine (87%). Faeces (13%). METFORMIN: Onset of action: Within days, max effects up to 2 wks. Metabolism: Not metabolized by the liver. Bioavailability: Absolute: Fasting: 50%-60%. Half-life elimination: Plasma: 4-9 hrs. Blood: Approx. 17.6 hrs. Time to peak, serum: Immediate release: 2-3 hrs. Extended release: 7 hrs. (Range: 4-8 hrs). Excretion: Urine.

Compiled by Healify Pharmacy from published drug references. How we compile it →

Always consult a pharmacist or doctor.