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Lack of Effectiveness
Some of the widely prescribed muscle relaxants covered on this web site have been on the market for more than 40 years. Yet five of these drugs were among the top 200 most frequently prescribed medications in the United States in 2002, with more than 30 million prescriptions dispensed. Of course, there is nothing necessarily wrong with older drugs per se. Many of the proven, safest, and most effective products are older drugs. The problem with this particular group of...
Lack of Effectiveness
Some of the widely prescribed muscle relaxants covered on this web site have been on the market for more than 40 years. Yet five of these drugs were among the top 200 most frequently prescribed medications in the United States in 2002, with more than 30 million prescriptions dispensed. Of course, there is nothing necessarily wrong with older drugs per se. Many of the proven, safest, and most effective products are older drugs. The problem with this particular group of drugs is that they have not disappeared from the market despite substantial shortcomings, including a lack of effectiveness and some serious adverse effects. Worse yet, some have become “blockbusters.”
Since their original marketing, there has been very little reliable evidence that these drugs actually relax muscles. The editors of The Medical Letter on Drugs and Therapeutics, a highly respected independent source of drug information written for pharmacists and physicians, wrote in 1961: “Some oral drugs, whether or not offered as muscle relaxants, do have a relaxing effect, but the evidence indicates that this effect results not from any specific action on the muscles, but rather from their central-nervous-system depressing sedative action.”[1]
In other words, these drugs work by causing drowsiness. In fact, the FDA-approved professional product labeling or package inserts for these drugs indicate that they do not directly relax muscles in people.
In 1961, the Medical Letter editors also commented on the therapeutic value of these drugs: “In a few controlled trials placebos have given much better results than some of the drugs.”
As with other therapeutic agents, the accumulating evidence of controlled clinical trials with muscle relaxants shows that neither favorable animal experiments, uncontrolled trials, nor wide acceptance by physicians can be relied upon to establish the value of a drug.[1]1
The American Medical Association concluded their 1986 review of the muscle relaxants by saying: “All spasmolytic (muscle-relaxing) drugs are superior to placebo in alleviating the symptoms and signs of localized muscle spasm. However, none of these agents have been shown conclusively to be more effective than analgesic-anti-inflammatory agents in relieving the pain of acute or chronic localized muscle spasm.”[2]
Although these muscle relaxants have been on the market for decades, their effectiveness, compared to that of anti-inflammatory drugs such as aspirin or ibuprofen, is still unknown. A 2003 systematic review of the muscle relaxants in the treatment of nonspecific low back pain found:
“Muscle relaxants are effective in the management of nonspecific low back pain, but the adverse effects require that they be used with caution. Trials are needed that evaluate if muscle relaxants are more effective than analgesics or nonsteroidal anti-inflammatory drugs.”[3]
