Markman et al., examine the stark contrast between the successes and failures of the clinical development of analgesics for different types of chronic low back pain (CLBP) syndrome over the past three decades. Multiple drugs with differing mechanisms of action have been developed for nonspecific axial-predominant low back syndromes and yet not a single therapy is indicated for any neuropathic low back pain syndrome (e.g., sciatica). Clinician findings have informed the entry criteria for neuropathic low back pain clinical trials, whereas entry criteria of axial CLBP trials have prioritized only patient reports of pain. This key difference could account for the lack of success in developing therapies for neuropathic low back pain in an era marked by successful development of analgesics for other types of CLBP as well as many chronic pain syndromes associated with nerve injury, such as postherpetic neuralgia (PHN) 1).
A wide range of medications are used to treat acute and chronic low back pain. Some are available over the counter (OTC); others require a physician’s prescription. Certain drugs, even those available OTC, may be unsafe during pregnancy, may interact with other medications, cause side effects, or lead to serious adverse effects such as liver damage or gastrointestinal ulcers and bleeding. Consultation with a health care provider is advised before use. The following are the main types of medications used for low back pain:
Analgesic medications are those specifically designed to relieve pain. They include OTC acetaminophen and aspirin, as well as prescription opioids such as codeine, oxycodone, hydrocodone, and morphine. Opioids should be used only for a short period of time and under a physician’s supervision. People can develop a tolerance to opioids and require increasingly higher dosages to achieve the same effect. Opioids can also be addictive. Their side effects can include drowsiness, constipation, decreased reaction time, and impaired judgment. Some specialists are concerned that chronic use of opioids is detrimental to people with back pain because they can aggravate depression, leading to a worsening of the pain.
Nonsteroidal anti-inflammatory drugs (NSAIDS) relieve pain and inflammation and include OTC formulations (ibuprofen, ketoprofen, and naproxen sodium). Several others, including a type of NSAID called COX-2 inhibitors, are available only by prescription. Long-term use of NSAIDs has been associated with stomach irritation, ulcers, heartburn, diarrhea, fluid retention, and in rare cases, kidney dysfunction and cardiovascular disease. The longer a person uses NSAIDs the more likely they are to develop side effects. Many other drugs cannot be taken at the same time a person is treated with NSAIDs because they alter the way the body processes or eliminates other medications.
Anticonvulsants—drugs primarily used to treat seizures—may be useful in treating people with radiculopathy and radicular pain.
Antidepressants such as tricyclics and serotonin and norepinephrine reuptake inhibitors have been commonly prescribed for chronic low back pain, but their benefit for nonspecific low back pain is unproven, according to a review of studies assessing their benefit.
Counter-irritants such as creams or sprays applied topically stimulate the nerves in the skin to provide feelings of warmth or cold in order to dull the sensation of pain. Topical analgesics reduce inflammation and stimulate blood flow.