Prednisone Drug Interactions

by on April 17, 2012

The discovery of corticosteroids in the late 40’s paved way to the FDA approval of prednisone in 1955 eventually leading to the wide use of the drug in modern medicine. Because of the many physiologic benefits of prednisone, it is among the most commonly-prescribed oral corticosteroids today.

Prednisone is in an inactive compound which is metabolized in the liver to convert it into its active form – prednisolone. Compared with naturally-occuring hydrocortisone, this synthetic corticosteroid is 4 times more potent. It is used for a wide variety of medical conditions that include asthma, rheumatoid arthritis, allograft rejection, systemic lupus erythematosus, severe allergic reactions, and many other inflammatory states.

How does prednisone work?

To understand how prednisone interacts with other drugs, it is important to know how it is metabolized by the body.

Basically, prednisone works by altering the immune and inflammatory responses of the body. After administering oral prednisone tablet, the gastrointestinal membrane readily absorbs the medication. It then takes effect in a matter of 1 to 2 hours. During the peak effect, the drug compounds breakdown and circulate through the system. It then binds with the plasma protein and is circulated through the body. When it gets to the liver, prednisone is metabolized to produce its active form – prednisolone. It will then be distributed throughout the system before it is eventually metabolized into inactive metabolites. These inactive compounds are filtered by the kidneys and excreted in the urine. It takes 18 to 36 hours for the medication to be completely cleared from the system.

How is prednisone affected by other drugs?

When prescribing prednisone, physicians would review the medical history of the client to check what other drugs are taken concurrently with the prednisone. The healthcare provider then adjusts the dose depending on the need of the patient.

Here are just some drugs that have clinically important drug interactions. Make sure to report to your physician if you are taking any of these drugs:

  • Phenobarbital, rifampin, barbiturates and phenytoin increase the clearance of prednisone hence may require higher dose to achieve desired blood levels.
  • Ketoconazole and troleandomycin increase the therapeutic and toxic effects of prednisone hence the dose may be lowered to prevent steroid overdose.
  • Estrogen and hormonal replacement therapy medications increase the therapeutic and toxic effects of prednisone.
  • Aspirin clearance is increased when taken along with prednisone. Taking prednisone can cause reduced aspirin serum levels or cause aspirin toxicity when abruptly discontinued. Use of aspirin and prednisone must be closely evaluated to avoid adverse side effects.
  • Anticoagulants such as Warfarin may have variable effects. Close supervision is necessary to maintain desired serum levels.
  • Diuretics increase the clearance of prednisone hence a higher dose may be required.
  • Using either Avelox (Moxifloxacin) or Cipro (Ciprofloxacin) with Predisone may increase your chances for developing tendinitis and tendor repture.
  • Using medications like Enbrel and Humira with Prednisone may increases the risks of developing serious infections.

This is just a partial list of drugs that may have direct interaction with prednisone. Make sure to discuss with your physician all the medications that you are taking including OTC drugs, natural products, vitamins and especially prescription medications before initiating prednisone therapy.