chlorzoxazone

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

---

chlorzoxazone

[-zok′səzōn]

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.

---

relaxant [re-lak´sant]

1. causing relaxation.

2. an agent that causes relaxation.

muscle relaxant an agent that specifically aids in reducing muscle tension.

---

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.

---

chlorzoxazone

a skeletal muscle relaxant.

---

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.