Chlorzoxazone

169.57

169.57

202-403-9

H0DE420U8G

756693|26189

DTXSID9022813

C28926

M - Musculo-skeletal system

2934999090

38.3

1.8

white to off-white Powder

1.5±0.1 g/cm3

191.5 °C

157.5±25.7 °C

1.674

H2O: 0.1 g/100 mL;DMSO: soluble 50mg/mL, clear

-20°C Freezer

Oral-rat LD50: 763 mg/kg; Oral-Mouse LD50: 440 mg/kg

Thermal decomposition releases toxic nitrogen oxides and chloride fumes

IRRITANT

NONH for all modes of transport

3

22-36/37/38-20/21/22

26-36-24/25-37/39

DM5250000

Xn,T,Xi

The warehouse is low-temperature, ventilated and dry; stored separately from food materials

Stable at room temperature in closed containers under normal storage and handling conditions.

P301 + P312 + P330-P305 + P351 + P338

H302-H315-H319-H335

|Warning|H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]|P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, and P501|Aggregated GHS information provided by 208 companies from 9 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

highly toxic

Oral, mouse: LD50 = 440 mg/kg; Oral, rat: LD50 = 763 mg/kg; Symptoms of overdose include diarrhea, dizziness, drowsiness, headache, light-headedness, nausea, and vomiting.

There have been no adequate prospective studies demonstrating the rates of ALT or AST elevations on chlorzoxazone therapy. Rare instances of clinical apparent liver disease possibly attributable to chlorzoxazone have appeared, including fatal cases. Such cases must be very rare, as this agent is widely used. While case reports have been few, in many instances chlorzoxazone was clearly implicated; furthermore, a related muscle relaxant with similar structure (zoxazolamine) was withdrawn from use in 1961, largely because of hepatotoxicity. The usual latency period is 1 to 4 weeks and the pattern of disease typically hepatocellular with marked elevations in ALT levels and jaundice, with minimal increases in alkaline phosphatase. Cholestatic enzyme elevations after exposure to chlorzoxazone have also been described. Allergic manifestations (rash and fever) are common, particularly in cases with a short latency (Case 1); autoantibodies are rare. Recovery is rapid once chlorzoxazone is stopped, but fatal cases have been reported, with disease progression despite early discontinuation of the agent (Case 2). There is rapid recurrence of injury with reexposure, often accompanied by fever.

13-18%

For the relief of discomfort associated with acute painful musculoskeletal conditions.

Chlorzoxazone is a centrally acting muscle relaxant commonly used for low back pain. Chlorzoxazone has been linked to rare instances of acute liver injury, a few of which have been fatal.

Autonomic Agents: Muscle Relaxants, Central

Chlorzoxazone is a centrally-acting agent for painful musculoskeletal conditions. Data available from animal experiments as well as human study indicate that chlorzoxazone acts primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex a.c. involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles.

A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents. They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358) (See all compounds classified as Muscle Relaxants, Central.)

Chlorzoxazone is rapidly metabolized and is excreted in the urine, primarily in a conjugated form as the glucuronide.

Chlorzoxazone is rapidly metabolized in the liver and is excreted in the urine, primarily in a conjugated form as the glucuronide.|Chlorzoxazone has known human metabolites that include 6-Hydroxychlorzoxazone.

Chlorzoxazone inhibits degranulation of mast cells, subsequently preventing the release of histamine and slow-reacting substance of anaphylaxis (SRS-A), mediators of type I allergic reactions. Chlorzoxazone also may reduce the release of inflammatory leukotrienes. Chlorzoxazone may act by inhibiting calcium and potassium influx which would lead to neuronal inhibition and muscle relaxation. Data available from animal experiments as well as human study indicate that chlorzoxazone acts primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm

Chlorzoxazone

2(3H)-Benzoxazolone, 5-chloro-: ACTIVE

Human Drugs -> FDA Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) -> Active Ingredients|Pharmaceuticals