What is Feldene?

Feldene is the brand name for the prescription drug piroxicam, a nonsteroidal anti-inflammatory medication used to relieve pain and inflammation. Feldene is available as an oral capsule and as an injectable solution.

Piroxicam belongs to a class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs). Other drugs in this class include ibuprofen (Advil, Motrin) and naproxen (Aleve). NSAIDs work by reducing the production of prostaglandins, substances that play a role in pain and inflammation.

The FDA approved Feldene in 1974. It’s manufactured by Pfizer.

Health Benefits

Feldene is used to relieve pain, inflammation, and stiffness caused by osteoarthritis and rheumatoid arthritis. It’s also used to treat juvenile rheumatoid arthritis in children who are at least 2 years old.

Feldene may also be used for purposes not listed in this medication guide.

Side Effects

Common side effects of Feldene include:

upset stomach, heartburn, gas, bloating,

nausea, vomiting, diarrhea;

constipation;

dizziness, headache, nervousness;

skin itching or rash; or

swelling in your hands or feet.

Dosages

The recommended adult dose of Feldene ranges from 20 mg to 40 mg daily. The maximum recommended dose is 20 mg per day for patients with kidney disease.

For the treatment of juvenile rheumatoid arthritis, the recommended dose of Feldene is 0.5mg/kg (up to 20 mg) once daily.

Interactions

NSAIDs like Feldene may interact with other medications you’re taking. Tell your doctor about all the drugs, vitamins, and herbal supplements you’re taking, especially:

a blood thinner such as warfarin (Coumadin);

steroids such as prednisone (Rayos) or methylprednisolone (Medrol);

lithium (Eskalith, Lithobid);

methotrexate (Rheumatrex, Trexall);

diuretics (‘water pills’);

ACE inhibitors such as benazepril (Lotensin), captopril (Capoten), fosinopril (Monopril), enalapril (Vasotec), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), and trandolapril (Mavik); or

heart or blood pressure medications such as amlodipine (Norvasc, Lotrel, Tekamlo, Tribenzor,Twynsta), diltiazem (Cartia XT, Cardizem CD, Dilacor XR, Dilt-CD,Diltia XT ,Taztia XT ), nifedipine (Adalat CC, Afeditab CR, Nifedical), verapamil (Calan, Covera HS, Isoptin SR, Verelan), and others.

Mechanism of Action

The precise mechanism of action of piroxicam is unknown. Studies in rats and mice have shown that piroxicam binds to albumin and a2-macroglobulin.

Piroxicam also inhibits prostaglandin synthesis through its action on cyclooxygenase (COX). Piroxicam was one of the first NSAIDs to be developed with the specific intention of inhibiting only COX-1, which is responsible for gastric mucosal damage. However, studies have shown that piroxicam is a non-selective COX inhibitor, meaning it inhibits both COX-1 and COX-2.

Pharmacokinetics

Feldene is rapidly and completely absorbed after oral administration. It undergoes minimal first-pass metabolism and has an absolute bioavailability of 100%. Peak plasma concentrations occur within 1-2 hours.

Piroxicam is extensively bound to plasma proteins (98%), mainly albumin. The volume of distribution of piroxicam is approximately 0.12 L/kg.

Piroxicam is metabolized in the liver by oxidative amidation and glucuronidation/sulfation. Approximately 50% of a dose is excreted in urine, 10% in feces, and 40% as unchanged drug in urine. The mean elimination half-life of piroxicam ranges from 18 to 24 hours.

Piroxicam is a substrate for the drug transporter P-gp. Therefore, inhibitors of P-gp may increase piroxicam concentrations while inducers of P-gp may decrease piroxicam concentrations.

Clinical Studies

The efficacy of Feldene in the signs and symptoms of osteoarthritis and rheumatoid arthritis was evaluated in controlled clinical trials of 3 to 6 weeks duration.

In these studies, the following adverse reactions were reported:

Gastrointestinal: abdominal pain, constipation, diarrhea, dyspepsia, flatulence, gastric irritation, gastrointestinal bleeding/ulceration, nausea, vomiting.

Cardiovascular: hypertension.

Central Nervous System: anxiety, dizziness, drowsiness, headache.

Dermatologic: rash.

Other: edema.

In controlled clinical trials, elevations of one or more liver enzymes occurred in approximately 1% of patients. These were usually reversible upon discontinuation of Feldene and were not associated with other clinical features.

Hepatic: abnormal liver function