indication

For relief of the signs and symptoms of rheumatoid arthritis and osteoarthritis. Also for the relief of mild to moderate pain.

pharmacology

Fenoprofen is a propionic acid derivative with analgesic, antiinflammatory and antipyretic properties. Fenoprofen inhibits prostaglandin synthesis by decreasing the enzyme needed for biosynthesis. In patients with rheumatoid arthritis, the anti-inflammatory action of fenoprofen has been evidenced by relief of pain, increase in grip strength, and reductions in joint swelling, duration of morning stiffness, and disease activity (as assessed by both the investigator and the patient). In patients with osteoarthritis, the anti-inflammatory and analgesic effects of fenoprofen have been demonstrated by reduction in tenderness as a response to pressure and reductions in night pain, stiffness, swelling, and overall disease activity (as assessed by both the patient and the investigator). These effects have also been demonstrated by relief of pain with motion and at rest and increased range of motion in involved joints. In patients with rheumatoid arthritis and osteoarthritis, clinical studies have shown fenoprofen to be comparable to aspirin in controlling the aforementioned measures of disease activity, but mild gastrointestinal reactions (nausea, dyspepsia) and tinnitus occurred less frequently in patients treated with fenoprofen than in aspirin-treated patients. It is not known whether fenoprofen causes less peptic ulceration than does aspirin. In patients with pain, the analgesic action of fenoprofen has produced a reduction in pain intensity, an increase in pain relief, improvement in total analgesia scores, and a sustained analgesic effect.

mechanism of action

Fenoprofen's exact mode of action is unknown, but it is thought that prostaglandin synthetase inhibition is involved. Fenoprofen has been shown to inhibit prostaglandin synthetase isolated from bovine seminal vesicles.

toxicity

Symptoms of overdose appear within several hours and generally involve the gastrointestinal and central nervous systems. They include dyspepsia, nausea, vomiting, abdominal pain, dizziness, headache, ataxia, tinnitus, tremor, drowsiness, and confusion. Hyperpyrexia, tachycardia, hypotension, and acute renal failure may occur rarely following overdose. Respiratory depression and metabolic acidosis have also been reported following overdose with certain NSAIDs.

biotransformation

About 90% of a single oral dose is eliminated within 24 hours as fenoprofen glucuronide and 4'-hydroxyfenoprofen glucuronide, the major urinary metabolites of fenoprofen.

absorption

Rapidly absorbed under fasting conditions, and peak plasma levels of 50 µg/mL are achieved within 2 hours after oral administration of 600 mg doses.

half life

Plasma half-life is approximately 3 hours.

drug interactions

Acenocoumarol: The NSAID, fenoprofen, may increase the anticoagulant effect of acenocoumarol.

Alendronate: Increased risk of gastric toxicity

Anisindione: The NSAID, fenoprofen, may increase the anticoagulant effect of anisindione.

Colesevelam: Bile acid sequestrants may decrease the absorption of Nonsteroidal Anti-Inflammatory Agents. Monitor for decreased serum concentrations/therapeutic effects of nonsteroidal anti-inflammatory agents (NSAID) if coadministered with bile acid sequestrants. Separating the administration of doses by 2 or more hours may reduce (but not eliminate) the risk of interaction. The manufacturer of colesevelam recommends that drugs should be administered at least 1 hour before or 4 hours after colesevelam.

Cyclosporine: Monitor for nephrotoxicity

Dicumarol: The NSAID, fenoprofen, may increase the anticoagulant effect of dicumarol.

Ginkgo biloba: Additive anticoagulant/antiplatelet effects may increase bleed risk. Concomitant therapy should be avoided.

Methotrexate: The NSAID, fenoprofen, may decrease the renal excretion of methotrexate. Increased risk of methotrexate toxicity.

Telmisartan: Concomitant use of Telmisartan and Fenoprofen may increase the risk of acute renal failure and hyperkalemia. Monitor renal function at the beginning and during treatment.

Timolol: The NSAID, Fenoprofen, may antagonize the antihypertensive effect of Timolol.

Trandolapril: The NSAID, Fenoprofen, may reduce the antihypertensive effect of Trandolapril. Consider alternate therapy or monitor for changes in Trandolapril efficacy if Fenoprofen is initiated, discontinued or dose changed.

Treprostinil: The prostacyclin analogue, Treprostinil, may increase the risk of bleeding when combined with the NSAID, Fenoprofen. Monitor for increased bleeding during concomitant thearpy.

Warfarin: The antiplatelet effects of fenoprofen may increase the bleed risk associated with warfarin. Consider alternate therapy or monitor for signs and symptoms of bleeding during concomitant therapy.