Methocarbamol and metaxalone are less sedating, although effectiveness evidence is limited. Adverse effects, particularly dizziness and drowsiness, are consistently reported with all skeletal muscle relaxants. The potential adverse effects should be communicated clearly to the patient.
Because of limited comparable effectiveness data, choice of agent should be based on side-effect profile, patient preference, abuse potential, and possible drug interactions. Skeletal muscle relaxants are often prescribed for musculoskeletal conditions including low back pain, neck pain, fibromyalgia, tension headaches, and myofascial pain syndrome. The goals of treatment include managing muscle pain and improving functional status so the patient can return to work or resume previous activities.
Skeletal muscle relaxants are not considered first-line therapy for musculoskeletal conditions. Skeletal muscle relaxants may be used as adjunctive therapy for acute low back pain. Antispasmodic agents should be used short-term two weeks for acute low back pain.
There is no clear evidence that one skeletal muscle relaxant is superior to another for musculoskeletal spasms. Choice of skeletal muscle relaxant should be based on individual drug characteristics and patient situation.
Skeletal muscle relaxants are divided into two categories: antispastic for conditions such as cerebral palsy and multiple sclerosis and antispasmodic agents for musculoskeletal conditions. Antispastic agents e. Rather, an antispasmodic agent may be more appropriate Table 1. Carisoprodol Soma 1. Dizziness, drowsiness, headache Rare idiosyncratic reactions mental status changes, transient quadriplegia, and temporary loss of vision after first dose; may require hospitalization Allergy-type reactions may occur after the first to fourth dose; may be mild e.
Physical or psychological dependence may occur; withdrawal symptoms may occur with discontinuation Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants Contraindicated in acute intermittent porphyria FDA pregnancy category C.
Chlorzoxazone Parafon Forte 2. Adults: to mg three to four times daily Children: to mg three to four times daily; or 20 mg per kg daily in three or four divided doses. Dizziness, drowsiness Red or orange urine GI irritation and rare GI bleeding Hepatoxicity rare ; discontinue with elevated liver function test. Avoid use in patients with hepatic impairment Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants FDA pregnancy category C.
Cyclobenzaprine Flexeril 3. Anticholinergic effect drowsiness, dry mouth, urinary retention, increased intraocular pressure Rare but serious adverse effects are arrhythmias, seizures, myocardial infarction. Seizures reported with concomitant use of tramadol Ultram ; combination should be avoided in patients with medical conditions that may induce seizures.
Contraindicated in patients with arrhythmias, recent myocardial infarction, or congestive heart failure. Diazepam Valium 4. Adults: 2 to 10 mg three to four times daily Children: 0. Dizziness, drowsiness, confusion Abuse potential. Long elimination half-life; avoid in older patients and in patients with hepatic impairment. Metaxalone Skelaxin 5. Drowsiness, dizziness, headache, nervousness Leukopenia or hemolytic anemia rare Liver function test elevation rare Nausea, vomiting, and diarrhea rare Paradoxical muscle cramps.
Use with caution in patients with liver failure Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants Less dizziness and drowsiness than other skeletal muscle relaxants FDA pregnancy category C.
Methocarbamol Robaxin 6. Black, brown, or green urine possible Mental status impairment Possible exacerbation of myasthenia gravis symptoms. Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants FDA pregnancy category C; reports of fetal abnormalities. Orphenadrine Norflex 7. Anticholinergic effect drowsiness, dry mouth, urinary retention, increased intraocular pressure Aplastic anemia rare GI irritation Confusion, tachycardia, hypersensitivity reaction with high doses.
Decreases effect of phenothiazines e. Tizanidine Zanaflex 8 , 9. Dose-related hypotension, sedation, and dry mouth Hepatotoxicity; monitor liver function tests at baseline and one, three, and six months Withdrawal and rebound hypertension may occur in patients discontinuing therapy after receiving high doses for long period of time; tapering is recommended. All of these drugs may cause increased drowsiness with central nervous system depressants.
Caution is advised when prescribing skeletal muscle relaxants in older patients. Estimated cost to the pharmacist based on average wholesale prices rounded to the nearest dollar in Red Book.
Montvale, N. Cost to the patient will be higher, depending on prescription filling fee. Information from references 1 through 9. Among antispasmodic agents, carisoprodol Soma , cyclobenzaprine Flexeril , metaxalone Skelaxin , and methocarbamol Robaxin were among the top drugs dispensed in the United States in The American Pain Society and the American College of Physicians recommend using acetaminophen and nonsteroidal anti-inflammatory drugs NSAIDs as first-line agents for acute low back pain and reserving skeletal muscle relaxants as an alternative treatment option.
Similar recommendations exist in treating tension headaches. Prescription rates for nonspecific back pain revealed that skeletal muscle relaxants accounted for This article presents evidence regarding the use of antispasmodic skeletal muscle relaxants for various musculoskeletal conditions, and appropriate drug selection if a skeletal muscle relaxant is required.
Highlights of contraindications, adverse effects, and drug interactions for these drugs are listed in Table 1. Many of the studies evaluating the effectiveness of skeletal muscle relaxants are hampered by poor methodologic design, including incomplete reporting of compliance, improper or no mention of allocation concealment, not utilizing intention-to-treat methods, and inadequate randomization. Some evidence appears to support nonbenzodiazepine skeletal muscle relaxants, such as carisoprodol, cyclobenzaprine, orphenadrine Norflex , and tizanidine Zanaflex , for acute low back pain.
One fair-quality study showed no difference between metaxalone and placebo. Cyclobenzaprine has been the most heavily studied drug, with consistently proven effectiveness. Cyclobenzaprine was found to be moderately more effective than placebo, but had more central nervous system adverse effects. The authors also described several limitations of the meta-analysis including inadequate blinding, heterogeneity among studies, and the presence of publication bias.
Skeletal muscle relaxants have also been studied as adjunctive therapy to analgesics in treating acute low back pain. In one open-label study 20 patients , the addition of cyclobenzaprine to naproxen Naprosyn resulted in a statistically significant decrease in muscle spasm and tenderness compared with naproxen alone.
Cyclobenzaprine has also been studied in treating fibromyalgia. A meta-analysis of five trials ranging from six to 24 weeks' duration included a total of patients with fibromyalgia. The authors reported that, although cyclobenzaprine moderately improved sleep and pain, the long-term benefits were unknown. This meta-analysis was limited by a high drop-out rate, short trial duration, few studies having an intention-to-treat design, and inadequate blinding.
Strong data comparing skeletal muscle relaxants to each other are scarce. A systematic review evaluated 46 trials head-to-head and placebo-controlled comprising mostly of studies on low back pain or neck syndromes. The placebo-controlled trials included 17 on cyclobenzaprine, six on tizanidine, four on carisoprodol, and four on orphenadrine, and were mostly conducted more than 15 years ago. The average patient enrollment was less than patients range 12 to patients.
In general, all of the drugs were shown to have some benefit. One fair-quality study showed carisoprodol was better than diazepam at improving muscle spasm and global and functional status in patients with low back pain. A different systematic review did include some studies which were considered to be high quality. Although the evidence for effectiveness of skeletal muscle relaxants in musculoskeletal conditions is limited, strong evidence does exist in terms of toxicity.
Selection of a skeletal muscle relaxant should be individualized to the patient. If there are tender spots over the muscle or trigger points on physical examination, a skeletal muscle relaxant is a reasonable adjunct to analgesic treatment of low back pain.
Skeletal muscle relaxants may also be used as an alternative to NSAIDs in patients who are at risk of gastrointestinal or renal complications. Patients with low back pain or fibromyalgia may benefit from treatment with cyclobenzaprine. Recent evidence showed similar effectiveness at half of its manufacturer recommended dose 5 mg , but with fewer adverse effects.
Higher doses of cyclobenzaprine or tizanidine would be appropriate to promote sedation in cases of more severe discomfort or perceived muscular spasm. Although there appears to be insufficient data on metaxalone and methocarbamol, these may be useful in patients who cannot tolerate the sedative properties of cyclobenzaprine or tizanidine. Of note, methocarbamol costs substantially less than metaxalone.
Carisoprodol is metabolized to meprobamate a class III controlled substance and has been shown to produce psychological and physical dependence.
Although all skeletal muscle relaxants should be used with caution in older patients, diazepam especially should be avoided in older patients or in patients with significant cognitive or hepatic impairment. Already a member or subscriber? Log in. Interested in AAFP membership? Learn more.
She received her doctor of pharmacy degree from Rutgers University College of Pharmacy in New Brunswick, NJ, and completed an inpatient family medicine pharmacy specialty residency at Deaconess Hospital and the St.
Louis College of Pharmacy in St. Louis, Mo. She received her doctor of pharmacy degree from St. Reprints are not available from the authors.
Carisoprodol carisoprodol tablet [package insert]. Philadelphia, Pa. Accessed January 14, Chlorzoxazone chlorzoxazone tablet [package insert]. Sellersville, Pa. Cyclobenzaprine hydrochloride cyclobenzaprine hydrochloride tablet [package insert]. Corona, Calif.
Diazepam diazepam tablet [package insert]. Miami, Fla. Skelaxin metaxalone [package insert]. Briston, Tenn. Methocarbamol methocarbamol tablet [package insert]. January 14, Although both medications are muscle relaxants, they are not exactly the same. Continue reading below to learn more about Skelaxin and Flexeril. Skelaxin is a skeletal muscle relaxant that contains metaxalone. It is available in brand and generic tablets. Skelaxin is used for short-term treatment. Flexeril is also a skeletal muscle relaxant—the active ingredient is cyclobenzaprine.
Flexeril is no longer available commercially as a brand-name product. Flexeril is only available as its generic, cyclobenzaprine. Cyclobenzaprine is also available in an extended-release form with the brand name of Amrix. Skelaxin and Flexeril are both indicated to be used along with rest, physical therapy, and other measures to relieve the discomfort of acute, painful musculoskeletal conditions like acute low back pain or neck pain.
Both drugs may be prescribed off-label for other conditions, but they are primarily used for muscle spasms. Also, the Flexeril manufacturer information states that the drug is not effective for spasticity associated with cerebral or spinal cord disease, or in children with cerebral palsy.
American Family Physician states that there is weak and very little evidence in terms of muscle relaxants and their efficacy compared to each other. They recommend that the selection of a muscle relaxant should be based on the potential for side effects, drug interactions, abuse, and also patient preference. This publication also reiterates the importance of short-term use of muscle relaxants and that physical therapy and other measures should be taken to prevent long-term use of a muscle relaxant.
Other medications such as Tylenol acetaminophen or nonsteroidal anti-inflammatory drugs NSAIDs , such as ibuprofen, may also be used. Your healthcare provider can determine if Skelaxin or Flexeril is appropriate for you. He or she will consider your symptoms, medical conditions, medical history, and any medications you take that may interact with Skelaxin or Flexeril. Most insurance plans typically cover Skelaxin in its generic form of metaxalone. Medicare Part D coverage varies.
Most insurance and Medicare Part D plans cover Flexeril generic. Brand-name Flexeril is not available. Both drugs can be very sedating. With either drug, an allergic reaction is rare but possible. Serotonin syndrome , a life-threatening condition due to serotonin buildup, is also possible. Skelaxin and Flexeril can potentiate the effects of alcohol, barbiturates, and other CNS depressants, such as benzodiazepines, opioids, antihistamines, and sedative-hypnotics.
There is an increased risk of serotonin syndrome when Skelaxin or Flexeril is taken with other drugs that increase serotonin; such as SSRI, SNRI, or tricyclic antidepressants; triptans for migraine; or cough and cold medications that contain dextromethorphan. Flexeril is structurally similar to tricyclic antidepressants such as amitriptyline and nortriptyline.
Because of this, there is an increased risk of seizures when taken with tramadol. Both Skelaxin and Flexeril interact with tramadol and other opioids —there is an increased risk of serotonin syndrome as well as additive CNS depression.
This is not a full list of drug interactions. Consult your healthcare provider for medical advice regarding drug interactions.
Skelaxin is a skeletal muscle relaxant used for the acute treatment of muscle spasms. The generic name for Skelaxin is metaxalone.
Flexeril is also a muscle relaxant used to treat skeletal muscle spasms. The generic name of Flexeril is cyclobenzaprine. Although Skelaxin and Flexeril are both in the same drug category skeletal muscle relaxants , they do have some differences, such as side effects, dose, and pricing, as outlined above.
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