Chlorzoxazon

BeschreibungChlorzoxazone 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.).

VerwendenChlorzoxazone is a benzoxazolone derivative that causes skeletal muscle relaxation and blocks spasticity in clinical studies. Chlorzoxazone enhances small and intermediate conductance calcium-activated potassium channels (EC50s = 87 and 98 μM for KCa2.2 and KCa3.1, respectively). The cytochrome P450 isoform CYP2E1 converts chlorzoxazone to 6-hydroxy chlorzoxazone . The urinary excretion of this 6-hydroxy metabolite is often used as a probe of CYP2E1 activity in studies of hepatotoxicity.