Brands, Medical Use, Clinical Data
- Nonsteroidal Antiinflammatory Agents (NSAIDs)
- Cyclooxygenase Inhibitors
- Tablet (extended-release)
- Tablet (immediate-release)
Brands / Synonyms
Allvoran; Apo-Diclo; Arthrotec; Assaren; Benfofen; Cataflam; Delphimix; Dichlofenac; Dichronic; Diclo-Phlogont; Diclo-Puren; Diclobenin; Diclofenac; Diclofenac Acid; Diclofenac Delayed Release; Diclofenac Potassium; Diclofenac Sodium; Diclord; Dicloreum; Dolobasan; Duravolten; Ecofenac; Effekton; Kriplex; Neriodin; Novapirina; Novo-Difenac; Novo-Difenac SR; Nu-Diclo; Pennsaid; Primofenac; Prophenatin; Rhumalgan; Solaraze; Solaraze T; Tsudohmin; Valetan; Voldal; Voltaren; Voltaren Ophtha; Voltaren Ophthalmic; Voltaren Rapide; Voltaren SR; Voltaren-XR; Voltarol; Xenid
For the acute and chronic treatment of signs and symptoms of osteoarthritis and rheumatoid arthritis.
Diclofenac is an acetic acid nonsteroidal antiinflammatory drug (NSAID) with analgesic and antipyretic properties. Diclofenac is used to treat pain, dysmenorrhea, ocular inflammation, osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and actinic keratosis
Mechanism of Action
The antiinflammatory effects of diclofenac are believed to be due to inhibition of both leukocyte migration and the enzyme cylooxygenase (COX-1 and COX-2), leading to the peripheral inhibition of prostaglandin synthesis. As prostaglandins sensitize pain receptors, inhibition of their synthesis is responsible for the analgesic effects of ketoprofen. Antipyretic effects may be due to action on the hypothalamus, resulting in peripheral dilation, increased cutaneous blood flow, and subsequent heat dissipation.
Completely absorbed from the gastrointestinal tract.
Symptoms of overdose include loss of consciousness, increased intracranial pressure, and aspiration pneumonitis. LD50=390mg/kg (orally in mice)
Biotrnasformation / Drug Metabolism
Diclofenac in all formulations, Cataflam, Voltaren, and Voltaren-XR, is contraindicated in patients with known
hypersensitivity to diclofenac and diclofenac-containing products. Diclofenac should not be given to patients who
have experienced asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs. Severe,
rarely fatal, anaphylactic-like reactions to diclofenac have been reported in such patients.
Aspirin: Concomitant administration of diclofenac and aspirin is not recommended because diclofenac
is displaced from its binding sites during the concomitant administration of aspirin, resulting in lower plasma
concentrations, peak plasma levels, and AUC values.
Anticoagulants: While studies have not shown diclofenac to interact with anticoagulants of the
warfarin type, caution should be exercised, nonetheless, since interactions have been seen with other NSAIDs. Because
prostaglandins play an important role in hemostasis, and NSAIDs affect platelet function as well, concurrent therapy
with all NSAIDs, including diclofenac, and warfarin requires close monitoring of patients to be certain that no
change in their anticoagulant dosage is required.
Digoxin, Methotrexate, Cyclosporine: Diclofenac, like other NSAIDs, may affect renal prostaglandins
and increase the toxicity of certain drugs. Ingestion of diclofenac may increase serum concentrations of digoxin and
methotrexate and increase cyclosporineís nephrotoxicity. Patients who begin taking diclofenac or who increase
their diclofenac dose or any other NSAID while taking digoxin, methotrexate, or cyclosporine may develop toxicity
characteristics for these drugs. They should be observed closely, particularly if renal function is impaired. In the
case of digoxin, serum levels should be monitored.
Lithium: Diclofenac decreases lithium renal clearance and increases lithium plasma levels. In
patients taking diclofenac and lithium concomitantly, lithium toxicity may develop.
Oral Hypoglycemics: Diclofenac does not alter glucose metabolism in normal subjects nor does it
alter the effects of oral hypoglycemic agents. There are rare reports, however, from marketing experiences, of
changes in effects of insulin or oral hypoglycemic agents in the presence of diclofenac that necessitated changes in
the doses of such agents. Both hypo- and hyperglycemic effects have been reported. A direct causal relationship has
not been established, but physicians should consider the possibility that diclofenac may alter a diabetic
patientís response to insulin or oral hypoglycemic agents.
Diuretics: Diclofenac and other NSAIDs can inhibit the activity of diuretics. Concomitant treatment
with potassium-sparing diuretics may be associated with increased serum potassium levels.
Other Drugs: In small groups of patients (7-10/interaction study), the concomitant administration of
azathioprine, gold, chloroquine, D-penicillamine, prednisolone, doxycycline, or digitoxin did not significantly
affect the peak levels and AUC values of diclofenac. Phenobarbital toxicity has been reported to have occurred in a
patient on chronic phenobarbital treatment following the initiation of diclofenac therapy.
In vitro, diclofenac interferes minimally or not at all with the protein binding of salicylic acid (20% decrease
in binding), tolbutamide, prednisolone (10% decrease in binding), or warfarin. Benzylpenicillin, ampicillin,
oxacillin, chlortetracycline, doxycycline, cephalothin, erythromycin, and sulfamethoxazole have no influence in vitro
on the protein binding of diclofenac in human serum.
Drug/Laboratory Test Interactions
Effect on Blood Coagulation: Diclofenac increases platelet aggregation time but does not affect
bleeding time, plasma thrombin clotting time, plasma fibrinogen, or factors V and VII to XII. Statistically
significant changes in prothrombin and partial thromboplastin times have been reported in normal volunteers. The mean
changes were observed to be less than 1 second in both instances, however, and are unlikely to be clinically
important. Diclofenac is a prostaglandin synthetase inhibitor, however, and all drugs that inhibit prostaglandin
synthesis interfere with platelet function to some degree; therefore, patients who may be adversely affected by such
an action should be carefully observed.