Study finds acetaminophen to be useless in relieving osteoarthritis pain

With this week's release of new guidelines aimed at driving down prescriptions for opioid pain medications, a new analysis of published research studies has found that, in older patients with osteoarthritis, acetaminophen provides no more pain relief and improvement in day-to-day function than does a placebo.

The study, published Thursday in the journal Lancet, found that several non-steroidal anti-inflammatory drugs (NSAIDs) had high probabilities of improving arthritis pain of the hips and knees. But only three of those found most effective -- 150 mg/day of diclofenac (a prescription drug marketed as Voltaren, Cambia and Cataflam), 1,000 mg/day of naproxen (marketed over the counter as Aleve and Naprosyn) and 1,200 mg/day of ibuprofen (marketed over the counter as Motrin, Advil, Nuprin) -- are available in the United States.

Two other NSAIDs found highly effective in the current study are not available in the United States. They are etoricoxib (Arcoxia), which was denied approval by the Food and Drug Administration in 2007 but is marketed in Europe, and rofecoxib (Vioxx), which was withdrawn from the U.S. market in 2004.

See the most-read stories in Science this hour >>

Two other NSAIDs, lumiracoxib (marketed as Prexige in only a few Central American countries) and Celecoxib (a prescription medication marketed in the United States as Celebrex) did not fare as well in the analysis. At daily doses of both 200 mg and 400 mg, Celecoxib, which is widely taken by arthritis patients in the United States, was found to reduce arthritis pain and improve function only marginally when compared with a placebo pill.

The analysis, conducted in Switzerland, folded together the findings of 74 randomized trials of painkillers conducted between 1980 and 2015 and reflected the response of 58,556 study participants.

In July 2015, the FDA issued orders that all NSAIDs sold in the United States warn that patients taking these medications increase their risk of heart attack and stroke. Those risks appear to rise with longer use of those drugs, the agency warned.

That makes those medications appropriate for short- or medium-term use, the authors noted. But while they can treat pain episodes, these medications aren't generally recommended for ongoing treatment of chronic pain.

The new analysis, which pooled data from 74 randomized trials published between 1980 and 2015, underscores the dilemma that physicians face in treating patients with chronic pain conditions such as osteoarthritis.

In a commentary also published in Lancet on Thursday, Dr. Nicholas Moore notes that the study's most remarkable result is that acetaminophen (called paracetamol in the United Kingdom) "does not seem to confer any demonstrable effect or benefit in osteoarthritis, at any dose."

This finding, he added "is not entirely unexpected. Paracetamol has been on the market for as long as most of us remember. Its efficacy has never been properly established or quantified in chronic diseases, and is probably not as great as many would believe."

Referring to concerns over acetaminophen's potential for liver toxicity, Moore added: "Its safety is also questioned, not just in overdose.”

With the addictive properties of opioid painkillers, the heart concerns surrounding NSAIDs and the apparent ineffectiveness of acetaminophen, the dearth of safe and effective painkillers is a particular problem for the roughly 27 million Americans over age 60 who suffer from osteoarthritis. Nearly twice as many women as men have the condition, which can impair mobility and discourage the kind of exercise that is probably one of the condition's most effective remedies. 

Follow me on Twitter @LATMelissaHealy and "like" Los Angeles Times Science & Health on Facebook.

MORE FROM SCIENCE

Could a gene-editing tweak make pigs organ donors for ailing humans?

From nitrogen glaciers to ice volcanoes: Pluto is defying all expectations

Vaccination aversion has fueled measles and whooping cough outbreaks, study finds

Copyright © 2016, Los Angeles Times
54°