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1. causing relaxation.
2. an agent that causes relaxation.
muscle relaxant an agent that specifically aids in reducing muscle tension.


Pharmacologic class: Autonomic nervous system agent

Therapeutic class: Skeletal muscle relaxant (centrally acting)

Pregnancy risk category C


Caplets: 500 mg

Tablets: 250 mg, 500 mg

Indications and dosages

Adjunct to rest and physical therapy in treatment of muscle spasms associated with acute, painful musculoskeletal conditions

Adults: 250 to 750 mg P.O. three to four times daily


• Hypersensitivity to drug
• Hepatic impairment


Use cautiously in:
• underlying cardiovascular disease, renal impairment
• children (safety not established).


• If desired, crush tablets and mix contents with food or water.
• Don't withdraw drug abruptly.

Adverse reactions

CNS: dizziness, drowsiness, light-headedness, malaise, headache, over-stimulation, tremor

GI: nausea, vomiting, constipation, diarrhea, heartburn, abdominal distress, anorexia

GU: orange or purplish-red urine

Hepatic: hepatic dysfunction

Skin: allergic dermatitis, urticaria, erythema, pruritus, petechiae, ecchymosis, angioedema

Other: allergic reactions


Drug-drug.CNS depressants (including antihistamines, antidepressants, opioids, sedative-hypnotics): increased risk of CNS depression

Drug-diagnostic tests.Alanine aminotransferase, alkaline phosphatase, bilirubin: increased levels

Drug-herbs.Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Drug-behaviors.Alcohol use: increased sedation

Patient monitoring

Stay alert for signs and symptoms of hepatic dysfunction. Withhold drug and notify prescriber if these occur.
• Monitor hepatic enzyme and serum electrolyte levels.

Patient teaching

Instruct patient to promptly report yellowing of eyes or skin.
• Caution patient not to consume alcohol during therapy.
• Instruct patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Tell patient that drug may turn his urine orange or purplish-red.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.


/chlor·zox·a·zone/ (klor-zok´sah-zōn) a skeletal muscle relaxant used to relieve discomfort of painful musculoskeletal disorders.


a skeletal muscle relaxant.
indication It is prescribed for the relief of muscle spasm.
contraindications Impaired liver function and known hypersensitivity to this drug prohibit its use.
adverse effects Among the more serious adverse reactions are jaundice and GI bleeding.


n brand names: Paraflex, Parafon Forte DSC;
drug class: skeletal muscle relaxant, central acting;
action: depresses multisynaptic pathways in the spinal cord;
use: adjunct for relief of muscle spasm in musculoskeletal conditions.


a skeletal muscle relaxant.
References in periodicals archive ?
In this study, the effects of MA on the above-mentioned CYPs activities were also investigated in rat liver microsomes, employing phenacetin (CYP1A2), tolbutamide (CYP2C11), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and testosterone (CYP3A2) as the probe substrates.
Toxicokinetic interactions between orally ingested chlorzoxazone and inhaled acetone or toluene in male volunteers.
Human lymphocyte cytochrome P4502E1, a putative marker for alcohol-mediated changes in hepatic chlorzoxazone activity.
The reactions, including phenacetin-0-deethylation, tolbutamide 4-hydroxylation, dextromethorphan 0-demethylation, chlorzoxazone 6-hydroxylation and testosterone 6[beta]-hydroxylation, were used for detecting activities of CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A4, respectively.
Hydroxylation of chlorzoxazone as a specific probe for human liver cytochrome P450IIE1.
Metabolism of dextromethorphan to dextrorphan (CYP2D6-mediated) and chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1-mediated) was only minimally inhibited by PSP, with [IC.
Benzene poisoning, a risk factor for hematological malignancy, is associated with the NQO1 609C [right arrow] T mutation and rapid fractional excretion of chlorzoxazone.
Phenacetin, paracetamol, warfarin, furafylline, testosterone, 613-hydroxytestosterone, ketoconazole, 4-hydroxytolbutamide, tolbutamide, chlorzoxazone, 6-hydroxychlorzoxazone, chlorpropamide, chlorpheniramine, dextromethorphan, dextrorphan, sodium diethyl-dithiocarbamate, glucose 6-phosphate dehydrogenase (G6PDH), D-glucose 6-phosphate (G6P), [beta]-nicotinamicle adenine dinucleotide phosphate (NADP), and Tris-HCI were purchased from Sigma Chemical Co.
Low doses of nicotine and ethanol induce CYP2E1 and chlorzoxazone metabolism in rat liver.
1), on human CYP1A2, 2C9, 2E1 and 3A4 catalytic activity was investigated in vitro to determine the potential of Danshen in affecting CYP mediated phase I metabolism in human, using phenacetin (CYP1A2), tolbutamide (CYP2C9), chlorzoxazone (CYP2E1) and testosterone (CYP3A4) as the respective probe substrates.
However, another study showed the decreased oral clearance of chlorzoxazone with RasI homozygous variants in Japanese residents of Hawaii (Marchand et al.