Metformin drug interactions

From Pubdrug

Non-certified

You are reading a non-certified PubDrug document. This document is incomplete and not ready for final editing, review, and certification. Until this document is certified, any registered PubDrug user may edit its content.

Authored by: Rlweber 08:48, 20 March 2007 (PDT)

The majority of drug interactions with metformin include those that induce hyperglycemia, those that compete with metformin for common renal tubular transport systems, those that increase the risk of lactic acidosis and those that can lead to hypoglycemia.

Contents 1 Drugs That Lead to Loss of Glycemic Control (Induce Hyperglycemia) 2 Drugs That Compete with Metformin for Common Renal Tubular Transport Systems (Increase Risk of Lactic Acidosis) 3 Drugs/Herbs That May Cause Hypoglycemia 4 Radiopaque Contrast Media 5 Cimetidine 6 References

Drugs That Lead to Loss of Glycemic Control (Induce Hyperglycemia)

Atypical antipsychotics such as aripiprazole, clozapine, olanzapine, quetiapine, risperidone, and ziprasidone cause hyperglycemia, diabetic ketoacidosis and diabetic coma. ^[1] Clonidine may potentiate or weaken the hypoglycemia effects of anti-diabetic medications. Corticosteroids may weaken the hypoglycemia effects of metformin due to their ability to increase blood glucose levels.^[2] Cyclosporine may cause hyperglycemia.^[2] Niacin may cause hyperglycemia, via its ability to interfere with glucose metabolism.^[2] Phenytoin/fosphenytoin, cyclosporine, isoniazid, estrogens/progestins, diuretics (torsemide, furosemide, bumetanide)and oral contraceptives may also lead to hyperglycemia.^[2]

Drugs That Compete with Metformin for Common Renal Tubular Transport Systems (Increase Risk of Lactic Acidosis)

Adefovir, amiloride, entecavir , cimetidine, lamivudine, midodrine, trospium, digoxin, procainamide, triamterene, trimethoprim, ranitidine, quinidine, quinine, morphine, trimethoprim, and vancomycin may increase the risk of lactic acidosis.^[2] These drugs are cationic drugs, which are also elimiated by renal tubular secretion. They may interact with metformin by competing for renal tubular transport systems, resulting in decreased elimination of metformin.

Drugs/Herbs That May Cause Hypoglycemia

Although metformin itself does not cause hypoglycemia, co-administration of metformin with blood glucose-lowering drugs may increase the risk of hypoglycemia. These drugs include androgens, ACE Inhibitors, clonidine, beta-blockers, Antihyperglycemic Agents, fibric acid derivatives, fluoxetine, guanethidine, disopyramide, chromium and garlic.^{[3] [4] [2]}

Radiopaque Contrast Media

Any patient who is going to have a diagnostic test performed, involving the use of radiopaque contrast media, should stop metformin prior to the procedure and withhold for at least 48 hours. Radiopaque contrast media can increase the risk of lactic acidosis.^{[2] [5]}

Cimetidine

Cimetidine can increase the peak and whole blood concentration of metformin, and consequently increase the risk of lactic acidosis.^{[2] [6]}

Back to Metformin

References

1. ↑ Luna B, Feinglos MN. Drug-induced hyperglycemia. JAMA 2001;286:1945—8.
2. ↑ ^{2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7} Lexi-Comp (2003). Drug Information Handbook. 11th Edition., APhA
3. ↑ Anderson RA, Cheng N, Bryden NA, et al. Elevated intakes of supplemental chromium improve glucose and insulin variables in individuals with type 2 diabetes. Diabetes 1997;46:1786—91.
4. ↑ Sheela CG, Kumud K, Augusti KT. Anti-diabetic effects of onion and garlic sulfoxide amino acids in rats. Planta Med 1995;61:356—7.
5. ↑ Glucophage®/Glucophage® XR (metformin) package insert. Princeton, NJ: Bristol-Myers Squibb Company; 2003 Apr.
6. ↑ Somogyi A, Stockley C, Keal J, Rolan P et al. Reduction of metformin renal tubular secretion by cimetidine in man. Br J Clin Pharmacol 1987;23:545—51.