Opioids in the Treatment of Acute Low Back Pain
Were you prescribed an opioid to relieve your acute lower back pain? Read on for more details about this medicaiton.
Opioids occupy the second rung on the World Health Organization (WHO) analgesic ladder in the treatment of moderate to severe cancer pain and are commonly prescribed for postoperative pain, where they have been found to successfully treat both local and more generalized pain symptoms.
Opioid drugs produce analgesia by binding to multiple types of opioid receptors, which are typically bound by endogenous opioid compounds. These receptors are generally classified as mu, kappa, and delta, but the opioid medications typically prescribed are morphine-like agonists, which occupy the mu receptor. These receptors are located both peripherally, on sensory nerves and immune cells, and centrally, in the spinal cord and brainstem.
In a study by Brown et al, the analgesic efficacy of diflunisal (Dolobid), 500-mg p.o. b.i.d. (by mouth, twice a day) following a 1000-mg loading dose was compared to that of 300-mg of acetaminophen with 30-mg of codeine in the treatment of pain resulting from initial or recurrent low back strains. Over this 15-day trial, the analgesic efficacy each regimen was found to be similar, but patient acceptability and tolerance were found to be superior for diflunisal. Five of 21 patients treated with acetaminophen and codeine reported adverse effects including drowsiness, dizziness, fatigue, and nausea, compared with three of 19 patients treated with diflunisal.
In a study of 200 patients presenting with acute low back strain, Weisel et al compared the analgesic efficacy of acetaminophen with codeine and aspirin plus oxycodone (ie, OxyContin). While all analgesic medications considered were not shown to result in a more prompt return to work, a significantly greater pain reduction, especially within the first three days of treatment, was noted for those individuals treated with codeine or aspirin plus oxycodone.
Peak Drug Effect: Important Consideration with Opioid Medications
For most opioids, peak drug effect occurs within one- and one-half to two-hours following oral administration, and a second opioid dose can safely be taken two-hours after the first if side effects are mild at that time. Sustained-release tablets are also available and often prove beneficial in those patients with more rapidly fluctuating pain. The potency of the opioid agonists is generally compared with that of morphine.
Tramadol hydrochloride (Ultram) is a centrally acting analgesic, which, although not chemically related to opiates, binds to mu receptors. Its mechanism of action is not completely understood, but is felt to be at least in part secondary to its inhibition of the reuptake of both serotonin and norepinephrine. Tramadol has been demonstrated to provide superior analgesia to combined acetaminophen-propoxyphene (ie, Darvocet) in patients experiencing severe postoperative pain, and similar analgesia, but with greater tolerability, to morphine in patients hospitalized for cancer pain.
In a four-week study of 390 elderly patients with chronic pain secondary to a variety of conditions, tramadol was found to provide comparable analgesia to acetaminophen with codeine without a significant difference in associated adverse effects. Additional studies reveal the low abuse potential and the absence of significant respiratory depression associated with tramadol use. Individualization of tramadol dosage is recommended for those individuals either over 75 years of age, with impaired renal function, and with significant liver disease.
The goal of successful opioid prescription involves achieving a tolerable balance between analgesia and the side effects often associated with opioid use. Tolerance to adverse effects such as somnolence (sleepiness), nausea, and impaired thought processes typically occurs within days to weeks of initial opioid administration. Constipation is a more persistent side effect, which can be managed with stool softeners and laxatives. Normeperidine, a metabolite of meperidine (Demerol), accumulation with repetitive dosing has been associated with the development of anxiety, tremors, myoclonus (muscle spasm) and generalized seizures; patients with impaired renal function are at particular risk. Methadone (Dolophine) demonstrates good oral potency and a plasma half-life of 24-36 hours. Accumulation of methadone may occur with repetitive dosing, resulting in excessive sedation on days two to five. Physical dependence can develop after several days of administration of opioid analgesics.
Other Articles in This Acute Low Back Pain Treatments Series
- Medications and Treatment of Acute Low Back Pain
- Acetaminophen in the Treatment of Acute Low Back Pain
- Non-steroidal Anti-inflammatories (NSAIDs) in the Treatment of Acute Low Back Pain
- Muscle Relaxants in the Treatment of Acute Low Back Pain
- Opioids in the Treatment of Low Back Pain
- Corticosteroids in the Treatment of Low Back Pain
- Colchichine in the Treatment of Low Back Pain
- Anti-depressant Medications Used to Treat Low Back Pain
- Conclusion: Acute Low Back Pain and Medication
Despite the stigmas and fears of addiction associated with their use, when properly utilized by a knowledgeable physician, opioid analgesics successfully treat otherwise intractable pain.
The potential role of opioids in the treatment of non-malignant acute low back pain is limited; reserved for those patients who have either failed to realize adequate analgesia from alternative medications, ie,. NSAIDs plus or minus a muscle relaxant, or who have contraindications to the use of other 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 faciliate 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. Chronic opioid treatment may be an option in selected patients who have failed all other treatments. These patients should be monitored for appropriate medication use on regular intervals.