OTC ANALGESIC DOSES OF ACETAMINOPHEN AND IBUPROFEN
OTC ANALGESIC DOSES OF ACETAMINOPHEN AND IBUPROFEN in osteoarthritis of the knee showed comparable efficacy to prescription dosage regimens of ibuprofen in an Indiana University School of Medicine study published in The New England Journal of Medicine July 11. The study randomized 184 patients to receive either 1,200 or 2,400 mg of ibuprofen per day or 4,000 mg/day of acetaminophen for four weeks. The study was supported by a grant from the National Institute of Arthritis and Muscoloskeletal and Skin Diseases. All three regimens produced a 10%-12% decrease in overall pain scores based on patient questionnaires, the study found. Both ibuprofen groups showed similar decreases in "rest pain" and "walking pain," while acetaminophen showed "slight but significant improvements" in patient-assessed disability and in walking speed. The only statistically-significant difference among the three regimens, the study says, was a greater decrease in rest pain in both ibuprofen groups compared to acetaminophen. Researchers found a similar number of adverse events in the three groups. They also found statistically significant changes in laboratory test values of kidney and liver enzyme levels. High- dose ibuprofen showed an increase in serum creatinine levels (suggesting an effect on the kidneys) while acetaminophen showed an increase in aspartate aminotransferase concentration (indicating an effect on the liver). "The present results call into question the routine use of a high (i.e., anti-inflammatory) dose of ibuprofen for osteoarthritis of the knee," the researchers concluded. By inference, the researchers call into question the use of high dose nonsteroidal anti-inflammatory drugs in general as a treatment for osteoarthritis. "Over the past decade the dosages of NSAIDs recommended for the treatment of arthritis have risen," the article notes. "Associated with this shift are increases in prescription costs and the risks of adverse drug effects, particularly gastrointestinal blood loss and gastric erosions." The researchers therefore recommend a "careful assessment of the comparative advantages and disadvantages of analgesic agents and NSAIDs in the treatment of osteoarthritis." In an accompanying editorial, Matthew Liang, MD, Brigham and Women's Hospital, and Paul Fortin, MD, McGill University, contend that the Indiana study "challenges the reflexive prescription of nonsteroidal anti-inflammatory drugs for osteoarthritis." The authors note that the study raises the questions: "Would another NSAID. . . have produced different results? Would long-term results have been the same?" Nonetheless, the editorial asserts, "the study stands as the most rigorous test of whether use of an NSAID is better than simple analgesic drugs in the treatment of symptomatic osteoarthritis of the knee." Upjohn, which markets both a prescription ibuprofen (Motrin) and an OTC (Motrin IB) commented that the absence of a placebo group and the short duration of the study limit its usefulness. The company noted that osteoarthritis is a longterm and variable disease and so believes that only limited conclusions can be drawn from the four-week study. Whitehall, manufacturer of the OTC ibuprofen Advi, stressed the safety data: "The maximum OTC dose of ibuprofen was comparable to the maximum OTC dose of acetaminophen in the incidence of reported gastrointestinal side effect(BRACKET)s(BRACKET)." The company noted that low-dose ibuprofen was the only regimen not associated with a change in liver or kidney function, while acetaminophen raised AST. "The clinical significance of the liver finding, however, is unclear," Whitehall noted.
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