Limbrel Prescription Food for Osteoarthritis

Is Limbrel Beneficial for Osteoarthritis?

Blue capsules
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Limbrel (flavocoxid) is a prescription medical food for the treatment of osteoarthritis. Some arthritis patients have been confused by the name and terminology associated with Limbrel.

The brand name "Limbrel" is very close to the brand name "Enbrel" (one of the TNF blocker drugs used to treat rheumatoid arthritis). Also, the generic name for Limbrel, flavocoxid, may be easily confused with COX-2 selective inhibitors, such as celecoxib (brand name Celebrex).

The differences are vast, and the confusion is a concern.

What Is a Medical Food?

Limbrel is classified as a medical food, not as a drug or dietary supplement. Medical foods have their own regulatory requirements and are regulated by the Center for Food Safety and Applied Nutrition, a Food Division of the FDA.

Medical foods are available by prescription only. According to the FDA, "A medical food, as defined in section 5(b)(3) of the Orphan Drug Act (21 U.S.C. 360ee(b)(3)), is a food which is formulated to be consumed or administered enterally under the supervision of a physician and which is intended for the specific dietary management of a disease or condition for which distinctive nutritional requirements, based on recognized scientific principles, are established by medical evaluation."

Medical foods are not meant to be used by the general public. Medical foods are not those foods included within a healthy diet intended to decrease the risk of disease, such as reduced-fat foods, low-sodium foods, or weight loss products.

What's in Limbrel?

Limbrel contains flavocoxid, a blend of concentrated flavonoids, primarily baicalin and catechin. Primus Pharmaceuticals, Inc., the company which markets Limbrel in the U.S., claims that the ingredients in Limbrel have both anti-inflammatory and antioxidant properties in a concentrated form which cannot be obtained through normal diet.

The Mechanism of Limbrel

According to Primus Pharmaceuticals, Limbrel restores the body's normal metabolic inflammatory processes through the dual inhibition of excess arachidonic acid metabolization and antioxidant action. Limbrel manages production of arachidonic acid metabolites while inhibiting COX-1, COX-2, and 5-LOX (5-lipoxygenase), all of which may contribute to osteoarthritis.

Safety and Efficacy of Limbrel

More than 27 million Americans have osteoarthritis. Any approach to managing the pain and disability associated with osteoarthritis is helpful, even if only for a subset of patients, as long as it is considered safe and effective.

According to the manufacturer's website, "In two randomized, double-blind, placebo-controlled human clinical studies, safety testing was performed on the Limbrel formula, monitoring 43 serum analytes, hematological and serological parameters, lipid profiles, liver enzymes, renal markers (BUN/creatinine ratios and creatinine clearance). One clinical trial studied 80 patients for 60 days and the other trial studied 60 patients over 90 days. In both clinical trials, Limbrel caused no change in any blood electrolytes, serology, liver enzyme, liver enzymes, or renal markers over the test period.

Side effects observed were comparable to placebo in both clinical studies as well." The data is on file with the company but unpublished in scientific journals.

More Limbrel Studies

In 2010, a study was conducted that compared the safety and effectiveness of Limbrel (500 mg twice daily) to naproxen (500 mg twice daily) in 220 patients with moderate to severe knee osteoarthritis over a 12-week period. Results revealed that Limbrel was as effective as naproxen for managing signs and symptoms of knee osteoarthritis. Limbrel had better upper gastrointestinal, renal, and respiratory safety profiles than naproxen.

A subsequent analysis, which considered subsets of patients, tended to favor Limbrel over naproxen in terms of effectiveness, though, especially among patients over 60 years old, males with milder disease, those with lower disease activity, and those with better walking times at the start of the study. 

Acute Liver Injury and Limbrel

Four patients were suspected of having acute liver injury due to Limbrel (flavocoxid) use. According to the report in the Annals of Internal Medicine (2012), "A network of 8 clinical centers and 1 data coordinating center enrolled 877 patients with suspected drug-induced liver injury between 2004 and 2010. They collected serum, urine, and DNA for laboratory studies as well as other medical information on each patient, and they assessed the possible causes of the liver injury." It was concluded from the study that flavocoxid is capable of causing acute liver injury and it should be used with caution. Stopping the medical food reverses the adverse effect.

The Bottom Line

Safety of Limbrel continues to be monitored. Thousands of patients are being monitored in postmarketing surveillance associated with Limbrel.

Also, according to the website, "Limbrel's ingredients have GRAS (Generally Recognized As Safe) status according to strict FDA standards. For an ingredient to achieve GRAS status the requirements include a technical demonstration of non-toxicity and safety as well as general recognition and agreement on that safety by experts in the field."


Frequently Asked Questions About Medical Food. FDA. Revised August 2013.

Medical Food Available for Management of Osteoarthritis. Medscape. Paula Moyer, MA. February 21, 2006.

Efficacy and safety of flavocoxid, a novel therapeutic, compared with naproxen: a randomized multicenter controlled trial in subjects with osteoarthritis of the knee. Advances in Therapy. Levy RM et al. October 2010.

Efficacy and safety of flavocoxid compared with naproxen in subjects with osteoarthritis of the knee - a subset analysis. Advances in Therapy. Levy R et al. December 2010.

Acute Liver Injury due to Flavocoxid (Limbrel), a Medical Food for Osteoarthritis. Annals of Internal Medicine. 19 June 2012, Vol 156, No. 12.

Limbrel. Accessed 10/19/15.