metaxalone

metaxalone

(me tax' ah lone)

Skelaxin

Pregnancy Category C

Drug class

Skeletal muscle relaxant (centrally acting)

Therapeutic actions

Precise mechanism of action not known, but may be due to general CNS depression; does not directly relax tense skeletal muscles or directly affect the motor endplate or motor nerves.

Indications

·        Adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal disorders

Contraindications and cautions

·        Contraindicated with hypersensitivity to metaxalone; tendency for hemolytic or other anemias; severe renal or hepatic disfunction, lactation.

·        Use cautiously with mild liver dysfunction, pregnancy.

Available forms

Tablets—400, 800 mg

Dosages

ADULTS AND PATIENTS > 12 YR

800 mg PO tid–qid.

PEDIATRIC PATIENTS < 12 YR

Not recommended.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	60 min	2 hr	4–6 hr

Metabolism: Hepatic; T_1/2: 2–3 hr

Distribution: Crosses placenta; may enter breast milk

Excretion: Urine

Adverse effects

·        CNS: Light-headedness, dizziness, drowsiness, headache, fever, blurred vision

·        Dermatologic: Urticaria, pruritus, rash

·        GI: Nausea, vomiting, GI upset, liver dysfunction

·        Other: Hemolytic anemia, leukopenia

Interactions

Drug-drug

·        Increased risk of sedation with other CNS depressants and alcohol

Drug-lab test

·        False-positive Benedict's test; use of a more specific glucose test is advised

Nursing considerations

Assessment

·        History: Hypersensitivity to metaxalone; tendency for hemolytic or other anemias; severe renal or hepatic dysfunction; lactation, pregnancy

·        Physical: T; skin color, lesions; orientation, affect, vision examination, reflexes; bowel sounds, normal output; CBC, LFTs, renal function tests

Interventions

·        Establish safety precautions if dizziness, drowsiness, blurred vision occur (use side rails, accompany patient when ambulating).

·        Arrange for analgesics if headache occurs (and possibly as adjunct for relief of discomfort of muscle spasm).

·        Provide positioning, massage, warm soaks as appropriate for relief of pain of muscle spasm.

·        Provide support and encouragement to deal with discomfort of underlying condition and drug effects.

Teaching points

·        Take this drug exactly as prescribed. Do not take a higher dosage than that prescribed.

·        Continue the use of rest, physical therapy, and other measures to relieve the discomfort.

·        Avoid the use of alcohol, sleep-inducing or over-the-counter drugs while you are taking this drug. These could cause dangerous effects. If you feel that you need one of these preparations, consult your health care provider.

·        You may experience these side effects: Drowsiness, dizziness (avoid driving a car or engaging in activities that require alertness if these occur); nausea (take drug with food and eat frequent small meals).

·        Report rash, itching, yellow discoloration of the skin or eyes.

Adverse effects in Italic are most common; those in Bold are life-threatening.