Description
Chlorzoxazone is a muscle relaxant. It acts by blocking nerve
impulses or pain sensations that are sent to brain. Typically, it
is used together with rest and physical therapy to treat skeletal
muscle conditions such as pain or injury. Chlorzoxazone,
5-chloro-2-benzoxazolione, is synthesized by a heterocyclization
reaction of 2-amino-4-chlorophenol with phosgene.
Skeletal muscle relaxants have conventionally been classified
into one group; however, they are actually a heterogeneous
group of medications commonly used to treat two different
types of underlying conditions – spasticity from upper motor
neuron syndromes and muscular pain or spasms from
peripheral musculoskeletal conditions. Medications classified
as skeletal muscle relaxants are baclofen, carisoprodol,
chlorzoxazone, cyclobenzaprine, dantrolene, metaxalone,
methocarbamol, orphenadrine, and tizanidine. These drugs
may impair mental and/or physical abilities required for
driving vehicles. As a class, skeletal muscle relaxants have
central nervous system (CNS)-related side effects: drowsiness,
dizziness, decreased alertness, blurred vision, and ataxia.
Their use has been associated with a twofold increase in the
risk for motor vehicle crashes. Muscle relaxants are included
in the ‘Beers List’ of potentially inappropriate medications
in older adults. Most muscle relaxants are poorly tolerated by
elderly patients because they cause anticholinergic adverse
effects, sedation, and weakness. Although extremely uncommon,
this compound may yield to idiosyncratic and
unpredictable type of liver toxicity. The concomitant use of
alcohol or other CNS depressants may have an additive effect.
Individuals on chlorzoxazone containing drugs should be
monitored for abnormal liver enzymes (e.g., aspartate transaminase
(AST), alanine transaminase (ALT), alkaline phosphatase,
bilirubin, etc.).
Originator
Paraflex ,McNeil, US ,1958
Definition
ChEBI: A member of the class of 1,3-benzoxazoles that is 1,3-benzoxazol-2-ol in which the hydrogen atom at position 5 is substituted by chlorine. A centrally acting muscle relaxant with sedative properties, it is used for the symptomatic treatment of painful mus
le spasm.
Manufacturing Process
A solution of 16.9 g (0.1 mol) of 2-amino-5-chlorobenzoxazole in 200 ml of 1
N HCl is refluxed until precipitation is complete. The resulting solid is collected
by filtration, dissolved in 200 ml of 1 N NaOH and the solution extracted with
50 ml of ether. Acidification of the alkaline solution gives a precipitate which is
purified by crystallization from acetone to give 2-hydroxy-5-chlorobenzoxazole
melting at 191° to 191.5°C.
General Description
Chlorzoxazone is a centrally active muscle relaxant used to treat painful muscle spasms linked to musculoskeletal disorders, such as fibrositis, bursitis, myositis, spondylitis, etc.
Pharmaceutical secondary standard for application in quality control. Provides pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards.
Toxicity evaluation
Chlorzoxazone is a white to off-white solid. It is soluble in organic solvents
such as ethanol, methanol, and dimethyl sulfoxide (DMSO).
