II. Indications
III. Contraindications
- Older patients
- Sleep Apnea
- Severe COPD
IV. Efficacy
V. Precautions
- Maximize Analgesics (NSAIDs and Acetaminophen) as they are generally more effective
- Dose as needed and primarily at night to assist sleep (primary effect is sedation)
- Limit to adjunctive (primarily bedtime use) in Acute Low Back Pain (and avoid in Chronic Low Back Pain)
- Avoid concurrent use of CNS Depressants (e.g. Alcohol, Benzodiazepines, Opioids)
- Risk of respiratory depression and death
VI. Agents: Preferred
-
Cyclobenzaprine (Flexeril) 5 mg (up to 10 mg) orally at bedtime up to three times daily
- Best studied of all antispasmodic agents, appears consistently effective, and is inexpensive
- Anticholinergic adverse effects (related to Tricyclic Antidepressants)
- Methocarbamol (Robaxin) 750 to 1500 mg four times daily
- Significantly less expensive than Flexeril
- Warn about Urine Color change
VII. Agents: Higher risk of Adverse Effects
- Chlorzoxazone (Parafon Forte) 250-750 mg 3-4 times daily
- Risk of liver abnormalities and GI upset
- Metaxalone (Skelaxin) 800 mg 3-4 times daily
- Risk of liver, hematologic abnormalities and GI upset
- Less effective and expensive
- Orphenadrine (Norflex) 100 mg twice daily
- Risk of Tachycardia, hematologic abnormalities and GI upset
- Orphenadrine with 770 mg Aspirin and 60 mg Caffeine (Orphengesic Forte)
- Very expensive ($25/tab) rebranding of an older Muscle relaxant
- Unclear if any Muscle relaxant is indicated (low efficacy) and risk of falls and Fractures in older adults
- Aspirin adds additional bleeding risk including Gastrointestinal Bleeding
- (2020) presc lett 27(9): 51
VIII. Agents: Higher risk of dependence
-
Carisoprodol (Soma) 350 mg up to four times daily
- Schedule IV drug in U.S. as of January 2012
- Risk of transient neurologic changes, serious Allergic Reactions, Substance Abuse, and fatal Overdoses
- Metabolized to Meprobamate, a Sedative and FDA controlled substance similar to Barbiturates
- See Carisoprodol Poisoning
- Benzodiazepines
IX. References
- (2017) Presc Lett 24(2): 9-10
- (2012) Presc Lett 19(1): 6
- Beebe (2005) Am J Ther 12(2): 151-71 [PubMed]
- Chou (2004) J Pain Symptom Manage 28(2):140-75 [PubMed]
- See (2008) Am Fam Physician 78: 365-70 [PubMed]
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Related Studies
| methocarbamol (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| METHOCARBAMOL 500 MG TABLET | Generic | $0.04 each |
| METHOCARBAMOL 750 MG TABLET | Generic | $0.05 each |
| chlorzoxazone (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| CHLORZOXAZONE 500 MG TABLET | Generic | $0.23 each |
| metaxalone (on 9/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| METAXALONE 400 MG TABLET | Generic | $3.85 each |
| METAXALONE 800 MG TABLET | Generic | $0.60 each |
| orphenadrine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| ORPHENADRINE ER 100 MG TABLET | Generic | $0.46 each |