Analgesics, Nonsteroidal anti-inflammatory drugs.

Diclofenac potassium immediate-release tablets contain the same therapeutic moiety diclofenac. They differ in the cationic portion of the salt, as well as in their release characteristics. Diclofenac potassium immediate release tablets are formulated to release diclofenac in the stomach. Diclofenac tablets are in a pharmaceutical formulation that resists dissolution in the low pH of gastric fluid but allows a rapid release of drug in the higher pH-environment of the duodenum. Conversely, diclofeanc tablets are formulated to release drug over a prolonged period. The primary pharmacokinetic difference between the three products is in the pattern of drug release and absorption.

In some fasting volunteers, measurable plasma levels are observed within 10 minutes of dosing with diclofenac potassium immediate release tablets. Peak plasma levels are achieved in approximately 1 hour in fasting normal volunteers, with a range from 0.33-2 hours.

The extent of diclofenac absorption is not significantly affected when diclofenac potassium tablets is taken with food. However, the rate of absorption is reduced by food, as indicated by a delay in Tmax and decrease in Cmax values by approximately 30%. After repeated oral administration of diclofenac potassium tablets 50 mg tid no accumulation of diclofenac in plasma occurred.

Diclofenac potassium immediate release tablets are indicated for the acute and chronic treatment of signs and symptoms of osteoarthritis and rheumatoid arthritis. In addition, diclofeanc potassium tablets and diclofenac tablets are indicated for the treatment of ankylosing spondylitis. Only diclofenac potassium tablets is indicated for the management of pain and primary dysmenorrheal, when prompt pain relief is desired, because it is formulated to provide earlier plasma concentrations of diclofenac.

Diclofenac in all oral formulations 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.

General
Diclofenac oral formulations should not be used concomitantly with other diclofenac containing products since they also circulate in plasma as the diclofenac anion.

Hematologic effects
Anemia is sometimes seen in patients receiving diclofenac or other NSAIDs. This may be due to fluid retention, GI blood loss, or an incompletely described effect upon erythropoiesis.

Renal Effects
As a class, NSAIDs have been associated with renal papillary necrosis and other abnormal renal pathology in long-term administration to animals. In oral diclofenac studies in animals, some evidence of renal toxicity was noted. Isolated incidents of papillary necrosis were observed in a few animals at high doses in several baboon subacute studies. In patients treated with diclofenac, rare cases of interstitial nephritis and papillary necrosis have been reported.

Adverse reaction information is derived from blinded and open-label clinical trials, as well as worldwide marketing experience. In the description below, rates of more common events represent clinical study results; rarer events are derived principally from marketing experience and publications and accurate rate estimates are generally not possible.

Worldwide reports of overdosage with diclofenac cover 66 cases. In approximately one half of these reports of overdosage, concomitant medications were also taken. The highest dose of diclofenac was 5.0 g in a 17 year old male who suffered loss of consciousness, increased intracranial pressure, aspiration pneumonitis and died 2 days after overdose. The next highest doses of diclofenac were 4.0 g and 3.75 g. The 24 year old female who took 4.0 g and the 28 and 42 year old females, each of whom took 3.75 g did not develop any clinically significant signs or symptoms. However there was a report of a 17 year old female who experienced vomiting and drowsiness after an overdose of 2.37 g of diclofenac.

In case of acute overdosage, it is recommended that the stomach be emptied by vomiting or lavage. Forced diuresis may theoretically be beneficial because the drug is excreted in the urine. The effect of dialysis or hemoperfusion in the elimination of diclofenac remains unproven. In addition to supportive measures, the use of oral activated charcoal may help to reduce the absoption of diclofenac.

Keep in cool, dry place and protect from moisture and light. Store at a temperature of 25°C.