Medications to Optimize Outcome in Low Back Pain

Various medications have been used in the treatment of low back pain. These include: acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, opioid analgesics, oral steroids, colchicines, and anti-depressant medications. Prior to prescribing these medications, the physiatrist should be aware of the contraindications, common side effects, and mode of action of each agent. Multiple divided dosing and intolerable side effects will limit the compliance with these medications.

Acetaminophen
Acetaminophen is safe and its analgesic effects make it acceptable for acute low back pain. It is inexpensive, and readily available to patients with few complications or risks. It is effective for mild to moderate pain in some patients but lacks other desirable effects on inflammation and muscle spasm. Its efficacy in moderate to severe low back pain is questionable and therefore, acetaminophen would not be considered a first line medication for most acute low back problems that present to the physiatrist unless there are contraindications to other medications. Often times, patients have attempted to obtain relief with acetaminophen prior to pursuing medical attention. The prolonged use of high dose acetaminophen is contraindicated and may lead to significant liver toxicity.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)
Nonsteroidal anti-inflammatory drugs are a reasonable first-line medication for pain control in low back pain; and, as the name implies, they theoretically offer additional anti-inflammatory effects. These effects are most prominent during the first week after injury. The dosage to produce anti-inflammatory effects is significantly different than for their analgesic effects. Most NSAID usage achieves only analgesic effects, as the dose prescribed is often too small and too infrequent to produce an anti-inflammatory effect. By carefully prescribing therapeutic doses at regular intervals, the analgesic and anti-inflammatory properties of these agents will be best realized by the patient. There are risks associated with NSAID use, especially in the elderly, in those with a history of peptic ulcer disease, hypertension, or renal insufficiency, NSAIDs are now being developed which are felt to pose a lower gastrointestinal risk via selective interaction with Cox-2 receptors. Prolonged use of these medications (i.e. greater than 4 weeks) should be avoided and is generally not indicated for most acute low back problems.

Muscle Relaxants
Medications that have been categorized as muscle relaxants may be helpful in some patients with low back pain and appear to have additional beneficial affects when used in conjunction with NSAIDs in the treatment of patients with low back pain.

The use of the term "muscle spasm" is in itself controversial, and these agents universally do not work at the muscular level. Commonly experienced undesirable side effects include drowsiness and fatigue. The use of benzodiazepines (tranquilizers) does not appear to be helpful or indicated in patients with acute low back pain. There is some concern with long-term use of carisoprodol (Soma®) as its active metabolite; meprobamate has been associated with withdrawal symptoms.

In summary, muscle relaxants can be used as short-term adjunctive medications and it is recommended that they be prescribed prior to bedtime to take advantage of their sedating effects and reduce daytime sedation.

Opioid Analgesics
The use of opioids in the treatment of low back pain should be limited to pain that is unresponsive to alternative medication, such as appropriately prescribed NSAIDs or when contraindications exist to the use of other analgesics. Opiates may appropriately be prescribed in the case of an acute disc herniation or other back injury in order to facilitate restoration of function and reduce unwanted compensatory strategies. When prescribed, opioids should be used on a defined dosing schedule and not on a p.r.n. (as needed) basis. Prolonged or repeated use of opioids is not recommended in the low back pain population.

Oral Steroids
Oral steroids are theoretically useful in patients with radiculopathy caused by disc herniation due to their strong anti-inflammatory effect. The inhibition of the inflammatory process by corticosteroids is more complete than that by NSAIDs, as the leukotriene mediated response (inflammation) is also diminished. Their effectiveness in the acute low back pain population remains unsupported by the literature, although studies are few. The use of oral corticosteroids in this patient population requires further clinical research and a more complete understanding of potential side effect risks.

Colchicine
Colchicine is no longer used by most physicians in the treatment of acute back pain. A few uncontrolled studies have found it to be effective in the relief of symptoms; however, well-designed trials do not exist. The use of colchicine can be associated with very serious adverse effects, which accounts for its limited use in the acute low back pain population. Further studies are needed before its use can be recommended.

Anti-Depressant Medications
Antidepressant medications are generally not necessary in the treatment of acute low back pain. Tricyclic antidepressants, and in particular amitriptyline, have been well studied and supported as useful analgesics in patients with pain of neurogenic origin. Their utility in the treatment of acute low back pain is less clear, yet they can be helpful as adjuncts for pain and sleep if used at bedtime. Doses should begin low and slowly increased to minimize side effects.