Article: Cyclobenzaprine

Cyclobenzaprine
Systematic (IUPAC) name
3-(5H-dibenzo[a,d]cyclohepten-5-ylidene)- N,N-dimethyl-1-propanamine
Identifiers
CAS number	303-53-7
ATC code	M03BX08
PubChem	2895
DrugBank	APRD00213
Chemical data
Formula	C20H21N
Mol. weight	275.387 g/mol
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	?

Cyclobenzaprine is a skeletal muscle relaxant and a central nervous system (CNS) depressant. It is marketed as Flexeril (5 and 10 mg tablets). Both the 5 and 10 milligram tablets are available generically.

Mechanism of action

The exact mechanism of action for cyclobenzaprine is unknown. Current research appears to indicate that cyclobenzaprine acts on the locus coeruleus where it results in increased norepinephrine release, potentially through the gamma fibers which innervate and inhibit the alpha motor neurons in the vetral horn of the spinal cord.[1] Decreased firing of the alpha motor neuron results in decreased muscular tone.

Indications

Cyclobenzaprine is typically prescribed to relieve pain and muscle spasms. Typically, muscle spasms occur in an injury to stabilize the affected body part and prevent further damage. The spasm of the muscles can actually increase the pain level. It is believed that by decreasing muscular spasm, pain is diminished. A common application would be that of a whiplash injury in a car accident.

It is also prescribed off-label as a sleep-aid.

Side effects

Common side effects include drowsiness, dizziness, and blurred vision. Other side effects are respiratory depression and decreased functionality in various muscles. Long term use has been associated with vision damage.

Interactions

Use of cyclobenzaprine with an SSRI (Selective Serotonin Reuptake Inhibitor) is not recommended and could lead to unpleasant and possibly damaging interactions. No deaths have been associated with cyclobenzaprine overdose, and permanent damage is almost always related to overactivity of relaxed muscles or contraindications with other drugs.

Legality

Cyclobenzaprine is regulated in the U.S. for prescription only. Cyclobenzaprine is unscheduled, however, and it is not illegal to have cyclobenzaprine in your possession, even without a prescription.

Abuse

Cyclobenzaprine is not widely abused, despite having an arguably high potential for abuse.

When used for illicit purposes, the drug is often referred to as "cyclone" with recreational doses ranging from 20 to 80 mg. At these dosages, users report mild to moderate drowsiness and relaxation as the primary effects. Compared with other commonly abused CNS depressants, cyclobenzaprine's effects are considered to be mild, limiting its popularity as a recreational drug.

As a generality, habitual drug users tend to steer clear of anti-depressants, because of the possibility of contraindications with other psychoactive drugs. Cyclobenzaprine, on the other hand, can induce moderate to severe anticholinergic effects at higher doses, as well as benzodiazepine-like sedation and often pleasurable muscle-relaxation. At even higher doses, cyclobenzaprine may cause severe ataxia, and due to excessive muscle-relaxation, and possibly disorienting side effects such as a floating sensation or other imagined movements (usually experienced when at rest.) Side effects such as these are directly related to the favoritism of newer, more mild antidepressant medications over tricyclic antidepressants.

Overdose

Although purportedly unpleasant, cyclobenzaprine is relatively benign in case of overdose, depending on its toxicity level in the user, and also on the susceptibility of the user to possibly harmful effects of overdose. Note that the susceptibility to these potentially damaging effects is greatly increased when cyclobenzaprine is used in conjunction with other drugs, particularly Central Nervous System Depressants and other antidepressants. Use of cyclobenzaprine with a MAOI (Mono Amine Oxidase Inhibitor) will very possibly result in fatality.

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