antidiabetics-oral (cont.)

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What drugs interact with type 2 oral diabetes medications?

Drug interactions with oral diabetes drugs vary based on individual diabetes drug classes. However, drugs that cause blood glucose levels to increase may diminish the effectiveness of any oral diabetes drug therapy. Examples of drugs which increase blood glucose include:

Metformin is eliminated from the body via the kidneys in a process known as renal tubular secretion. Drugs also that are eliminated via this same pathway may compete with metformin for elimination when taken or administered at the same time (concomitantly), and increase the risk of metformin associated side effects due to an increase in blood levels of metformin. Examples of such drugs include:

Due to the risk of lactic acidosis metformin containing products must be temporarily discontinued prior to the administration of radiopaque contrast dyes. Metformin should be held for at least 48 hours after contrast dye administration and should not be restarted until the patient's kidney function returns back to normal.

Sulfonylureas are broken down (metabolized) by a set of liver enzymes. Medications which inhibit or induce the activity of these enzymes may impact their blood levels.

Gemfibrozil (Lopid) strongly inhibits the breakdown of repaglinide and consequently may cause prolonged hypoglycemia.

Thiazolidinediones may interact with drugs that are strong inhibitors or inducers of liver certain enzymes known as CYP3A4, CYP2C8, or CYP2C9. The dose of pioglitazone must be limited to 15 mg when administered in combination with gemfibrozil (Lopid), a strong inhibitor of these pathways.

DPP-4 inhibitors are metabolized extensively by liver enzymes. Therefore, drug interactions are possible with agents that alter the function of these enzymes.

The effectiveness meglitinides may be reduced when administered with carbohydrate digesting enzymes such as amylase, pancreatin, or pancrelipase.

Bile acid sequestrants have many drug interactions. Bile acid sequestrants decrease the absorption of levothyroxine (Synthroid), glyburide (DiaBeta, Micronase), and birth control pills when taken together. Additionally, they also may decrease the absorption of other drugs such as:

  • warfarin (Coumadin),
  • digoxin (Lanoxin), and
  • fat-soluble vitamins (Vitamins A, D, E, and K).

Therefore, these agents should be administered at least 4 hours before the dose of colesevelam.

Bromocriptine is metabolized by CYP3A4 liver enzymes. Drugs which alter the activity of these enzymes may change bromocriptine levels in the blood and consequently cause adverse effects. Bromocriptine may also interact with some anti-psychotics and ergot based migraine medications.

Medically Reviewed by a Doctor on 5/18/2015