chlorzoxazone

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

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chlorzoxazone,

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.

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chlorzoxazone

a skeletal muscle relaxant.

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chlorzoxazone

Parafon Forte DSC, Strifon Forte (CA)

Pharmacologic class: Autonomic nervous system agent

Therapeutic class: Skeletal muscle relaxant (centrally acting)

Pregnancy risk category C

Action

Unclear. Thought to act on spinal cord and subcortical levels of brain, inhibiting multisynaptic reflex arcs responsible for skeletal muscle activity.

Availability

Caplets: 250 mg, 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

Contraindications

• Hypersensitivity to drug
• Hepatic impairment

Precautions

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

Administration

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

Route	Onset	Peak	Duration
P.O.	30-60 min	1-2 hr	3-4 hr

Adverse reactions

CNS: dizziness, drowsiness, light-headedness, malaise, headache, overstimulation, 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

Interactions

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.