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Incidence Greater Than 1%

The following adverse reactions were observed in clinical trials and included observations from more than 2,700 patients, 594 of whom were treated for one year and 248 for at least two years.

Gastrointestinal: The most frequently reported adverse reactions associated with meclofenamate sodium involve the gastrointestinal system. In controlled studies of up to six months duration, these disturbances occurred in the following decreasing order of frequency with the approximate incidences in parentheses: diarrhea (10% to 33%), nausea with or without vomiting (11%), other gastrointestinal disorders (10%), and abdominal pain¹. In long-term uncontrolled studies of up to four years duration, one third of the patients had at least one episode of diarrhea some time during meclofenamate sodium therapy.

In approximately 4% of the patients in controlled studies, diarrhea was severe enough to require discontinuation of meclofenamate sodium. The occurrence of diarrhea is dose related, generally subsides with dose reduction, and clears with termination of therapy. The incidence of diarrhea in patients with osteoarthritis is generally lower than that reported in patients with rheumatoid arthritis.

Other reactions less frequently reported were pyrosis¹, flatulence¹, anorexia, constipation, stomatitis, and peptic ulcer. The majority of the patients with peptic ulcer had either a history of ulcer disease or were receiving concomitant anti-inflammatory drugs, including corticosteroids which are known to produce peptic ulceration.

Cardiovascular: edema

Dermatologic: rash¹, urticaria, pruritus

Central Nervous System: headache¹, dizziness¹

Special Senses: tinnitus

Incidence Less Than 1%—Probably Causally Related

The following adverse reactions were reported less frequently than 1% during controlled clinical trials and through voluntary reports since marketing. The probability of a causal relationship exists between the drug and these adverse reactions.

Gastrointestinal: bleeding and/or perforation with or without obvious ulcer formation, colitis, cholestatic jaundice

Renal: renal failure

Hematologic: neutropenia, thrombocytopenic purpura, leukopenia, agranulocytosis, hemolytic anemia, eosinophilia, decrease in hemoglobin and/or hematocrit

Dermatologic: erythema multiforme, Stevens-Johnson Syndrome, exfoliative dermatitis

Hepatic: alteration of liver function tests

Allergic: lupus and serum sickness-like symptoms

Incidence Less Than 1%—Causal Relationship Unknown

Other reactions have been reported but under conditions where a causal relationship could not be established. However, in these rarely reported events, that possibility cannot be excluded. Therefore, these observations are listed to alert physicians.

Cardiovascular: palpitations

Central Nervous System: malaise, fatigue, paresthesia, insomnia, depression

Special Senses: blurred vision, taste disturbances, decreased visual acuity, temporary loss of vision, reversible loss of color vision, retinal changes including macular fibrosis, macular and perimacular edema, conjunctivitis, iritis

Renal: nocturia

Gastrointestinal: paralytic ileus

Dermatologic: erythema nodosum, hair loss

Warfarin

Meclofenamate sodium enhances the effect of warfarin. Therefore, when meclofenamate sodium is given to a patient receiving warfarin, the dosage of warfarin should be reduced to prevent excessive prolongation of the prothrombin time.

Aspirin

Concurrent administration of aspirin may lower meclofenamate sodium plasma levels, possibly by competing for protein binding sites. The urinary excretion of meclofenamate sodium is unaffected by aspirin, indicating no change in meclofenamate sodium absorption. Meclofenamate sodium does not affect serum salicylate levels. Greater fecal blood loss results from concomitant administration of both drugs than from either drug alone.

Propoxyphene

The concurrent administration of propoxyphene hydrochloride does not affect the bioavailability of meclofenamate sodium.

Antacids

Concomitant administration of aluminum and magnesium hydroxides does not interfere with absorption of meclofenamate sodium.

Carcinogenesis

An 18 month study in rats revealed no evidence of carcinogenicity.

Pregnancy

Meclofenamate sodium, like aspirin and other non-steroidal anti-inflammatory drugs, causes fetotoxicity, minor skeletal malformations, e.g., supernumerary ribs, and delayed ossification in rodent reproduction trials, but no major teratogenicity. Similarly, it prolongs gestation and interferes with parturition and with normal development of young before weaning. Meclofenamate sodium is not recommended for use during pregnancy, particularly in the 1st and 3rd trimesters based on these animal findings. There are, however, no adequate and well controlled studies in pregnant women.

Nursing Mothers

Trace amounts of meclofenamic acid are excreted in human milk. Because of the possible adverse effects of prostaglandin-inhibiting drugs on neonates, meclofenamate sodium is not recommended for nursing women.

Pediatric Use

Safety and effectiveness in children below the age of 14 have not been established.

REFERENCES

¹ Incidence between 3% and 9%. Those reactions occurring in 1% to 3% of patients are not marked with an asterisk.

Last reviewed on RxList: 4/7/2009
This monograph has been modified to include the generic and brand name in many instances.