Enbrel Dosage Schedule

Content provided by the Faculty of the Harvard Medical School

Enbrel Dosage Schedule

Question:

I have just been prescribed Enbrel 50mg twice a week for psoriasis and psoriatic arthritis, but I have conflicting information on how far apart the two doses should be administered. My doctor said to put four days between doses but I also was told the half-life of Enbrel is only about four days. On which day would you recommend I take it?

Answer:

Etanercept (Enbrel) is an injectable medication that is approved by the Food and Drug Administration for a number of conditions, including:

• Moderate to severe rheumatoid arthritis

• Psoriatic arthritis

• Psoriasis

• Ankylosing spondylitis

• Moderate to severe juvenile rheumatoid arthritis

The standard dose for psoriasis is 50mg twice a week. It's injected under the skin on the same days each week (for example, every Monday and Thursday). After three months, the medication should be reduced to a maintenance dosage of 50mg once a week.

During the first three months of treatment, when taken twice each week, the specific days don't matter as long as the medication is received at three- to four-day intervals. It's true that the half-life (the time it takes for half of the medication to be eliminated from the body or metabolized) is about four days. With twice-weekly dosing over a number of weeks, the amount of medication in the body is relatively constant.

It can be difficult to predict the precise effects of a medication based solely on its half-life and dosing interval. Studies demonstrate dramatic improvement in psoriasis with an acceptable safety profile when people received the medication twice each week.

Robert Shmerling, M.D., is associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center and an associate professor in medicine at Harvard Medical School. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program and has been a practicing rheumatologist for over 25 years.

Last updated:	July 20, 2009