What to Know About Rayos (Prednisone) for Rheumatoid Arthritis

A delayed-release corticosteroid for RA

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Rayos (delayed-release prednisone) is delayed-release formulation of low-dose prednisone, which is a corticosteroid. In 2012, this oral drug gained U.S. Food and Drug Administration (FDA) approval as a treatment for rheumatoid arthritis (RA). It's also used to treat several other conditions. Prednisone itself has been on the U.S. market since 1955.

In RA (and other autoimmune diseases), the immune system mistakenly identifies a healthy type of tissue as a threat to your health, as if it were a virus or other pathogen. It then launches an attack and tries to destroy that tissue. Prednisone is a common treatment for RA, because it counters resulting inflammation and changes how the immune system functions.

Rayos is known in Europe by the brand name Lodotra. So far, it's not available in generic forms or under other brand names.

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In RA, the joints (synovium) is the primary target for an immune system gone awry. The immune response triggers inflammation in the joints, which leads to pain, limited range of motion, and, eventually, permanent damage.

Early, aggressive treatment can prevent or delay permanent damage and the disability associated with it, and corticosteroids like Rayos—an anti-inflammatory and immunosuppressive agent—can be a useful part of that treatment.

Rayos works differently than immediate-release prednisone. Due to Rayos's formulation, taking the drug before bed allows it to take effect in the middle of the night—when certain cells in the immune system, called cytokines, start to increase. This mechanism of action appears to provide better control of cytokine-related inflammation in some people.

Rayos and other types of prednisone are typically used for short-term relief of inflammation in RA and autoimmunity in general, but some people do take these drugs long-term.

Rayos is also FDA-approved for organ transplantation along with an array of additional conditions, from other rheumatologic diseases to dermatologic issues, endocrine conditions, gastrointestinal diseases, respiratory concerns, infectious diseases, and more.

Besides RA, rheumatologic conditions Rayos may be used for include:

Your doctor may consider Rayos for you if you've recently been diagnosed with RA and are waiting to see the effects of a disease-modifying anti-rheumatic drug (DMARD) such as methotrexate, sulfasalazine, or Enbrel (etanercept). The effects of DMARDs can take weeks or even months to become evident, so prednisone and other corticosteroids play an important role during that time.

Later in the course of the disease, you may be given Rayos during RA symptom flares to help get your inflammation levels back down quickly. In addition, people with severe disease that's not adequately controlled by DMARDs or non-steroidal anti-inflammatory drugs may take prednisone long term.

Before Taking

Before taking Rayos, tell your doctor if you've ever had an allergic reaction to prednisone, similar drugs, or any of the active ingredients in Rayos.

Also, be sure to mention whether you've had recent or ongoing infections and whether you've recently had any vaccines.

Always be sure your doctor knows all the treatments you're using, including prescription drugs, over-the-counter medications, and supplements. This can help you avoid dangerous side effects and interactions that may be caused by certain combinations of therapies.

Precautions and Contraindications

People with certain health conditions shouldn't take Rayos, may need special monitoring while they're on it, or may need to discontinue other drugs before taking Rayos. Be sure to tell your doctor if you have:

You shouldn't start taking prednisone while you're pregnant, if you're trying to conceive, or while you have an infection.

Other Corticosteroids

Corticosteroids have been around a long time, and many of them are sold under numerous brand names. Because of this, they're often best known by their generic names.

Generic names of corticosteroid drugs include:

Some of these are primarily taken orally, while others may be used topically or taken via injection. Some are available in multiple forms.


Rayos is available in delayed-release tablets of 1 milligram (mg), 2 mg, and 5 mg strengths. Your doctor should determine the correct dosage for you based on several factors, including your disease severity and whether you've been using immediate-release prednisone.

Typically, the starting dose is 5 mg of Rayos once a day. However, if you've been taking rapid-release prednisone, prednisolone, or methylprednisolone, you should be given an equivalent initial dose of Rayos. (This may not be the same in milligrams, but it will be the same in strength.)

You should remain on the lowest amount that's effective for your symptoms (a.k.a. the maintenance dose).

Don't stop taking Rayos without talking to your doctor. Especially when going off of long-term or high-dose Rayos, you should do so gradually. Your doctor can advise you on how to properly taper this medication.

How to Take and Store

Rayos should be taken daily and with food. The pill must be swallowed whole—not cut, broken, or chewed—as this will interfere with the rate of release. Because the drug begins to get released four hours after taking the pill, patients commonly take this medication before they go to bed.

Rayos should be stored at about room temperature, with the optimal temperature being 77 degrees F.

If you're carrying the medication with you while you're away from the house, short stints of temperatures down to 59 degrees F and up to 86 degrees F are acceptable. You should keep Rayos tablets away from light and moisture.

Side Effects

As with any drug you are considering taking, Rayos's benefits must be weighed against potential side effects.


The most common side effects of Rayos include:

  • Fluid retention
  • Elevation in blood pressure
  • Change in glucose tolerance
  • Mood changes
  • Weight gain
  • Increased appetite

If any of these side effects become severe or don't go away with time, talk to your doctor.


More severe side effects are possible with Rayos and can stem from several body systems.

If you experience any new symptoms while taking this medication, contact your doctor right away.

Need for Monitoring

While you're on Rayos, especially long term, you'll need to be monitored for suppression of the hypothalamic-pituitary-adrenal, or HPA, axis (your body's stress-response system), Cushing's syndrome, and high blood sugars (hyperglycemia). Your blood pressure, sodium levels, and potassium levels should be closely watched as well. Be sure to get all of the tests your doctor suggests and to do so on schedule.

Warnings and Interactions

This drug will make you more susceptible to new infections and could cause a reactivation of latent chronic infections, so it's especially important to bring symptoms of infection (e.g., fever, chills, sore throat) to the attention of your doctor should they occur.

In addition, you should not get live or live-attenuated vaccines while taking an immunosuppressive dose of prednisone.

Pregnant or Nursing Women

Taking Rayos during the first trimester of pregnancy can harm your baby. It's associated with an increased risk of cleft lip and cleft palate, restricted growth, small birth weight, and premature birth. In animals, it's also been associated with miscarriages.

This drug does pass into breast milk and may cause problems with your child's growth and development.

You and your doctor should carefully weigh the benefits of this drug with the serious risks it poses to your baby, both before and after birth.

Drug Combinations

Prednisone can negatively interact with a long list of drugs and supplements, including common over-the-counter products such as:

Some common classes of drugs that can cause problems with Rayos are:

You and your doctor need to carefully evaluate the potential risks and benefits of Rayos before you start taking it, as your health changes over time, and whenever you start new medications.

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