Cyclobenzaprine, a tricyclic amine salt, is structurally related to the tricyclic antidepressants. Its exact mechanism of action is not entirely understood, but it is believed to work primarily at the level of the brainstem to reduce tonic somatic motor activity, influencing both gamma and alpha motor systems. By acting centrally rather than directly on skeletal muscles, Cyclobenzaprine helps to alleviate muscle spasms without interfering with muscle function.
The medication is usually administered orally, with its effects typically commencing within an hour and lasting up to 12 hours. Cyclobenzaprine is metabolised in the liver, primarily via the cytochrome P450 pathway, and is excreted mainly through the kidneys. Its half-life ranges from 8 to 37 hours, which may be prolonged in elderly patients and those with impaired hepatic function.