Specific concerns of certain muscle relaxants
Cyclobenzaprine: The prescriber should be aware that cyclobenzaprine is in fact a tricyclic compound nearly identical in structure to amitriptyline. Among tricyclic compounds, it is known to have among the highest risks of cardiac arrhythmias, including those resulting in fatal outcomes. Thus, caution is advised when using this agent, especially in older patients and/or in combination with other relevant medications.
Carisoprodol: The prescriber should be aware that carisoprodol is metabolized to the sedative-hypnotic agent meprobomate, a medication with a known risk for abuse. Carisoprodol has been taken off the market in Europe due to concerns regarding dependence.
Orphenadrine: This medication is similar in mechanism of action to diphenhydramine, and therefore may be associated with sedating and anticholinergic side effects.