General

Pronunciation
me-TAX -a-lone

Trade Name(s)

• Skelaxin

Pregnancy Category
Category Unknown

Ther. class.
skeletal muscle relaxants
(centrally acting)

Indications

Muscle spasm associated with acute painful musculoskeletal conditions (with rest and physical therapy)

Action

Skeletal muscle relaxation, probably as a result of CNS depression

Therapeutic Effect(s):
Skeletal muscle relaxation

Pharmacokinetics

Absorption: Well absorbed following oral administration

Distribution: Unknown

Metabolism and Excretion: Mostly metabolized by the liver; metabolites excreted in urine

Half-life: 2–3 hr

TIME/ACTION PROFILE

ROUTE	ONSET	PEAK	DURATION
PO	1 hr	2 hr	4–6 hr

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity

• Significant hepatic/renal impairment

• History of drug-induced hemolytic anemia or other anemia

Use Cautiously in:

• History of seizures

• Geri: Appears on Beers list. Poorly tolerated due to anticholinergic effects

• Pregnancy, lactation, or children <=12 yr (safety not established; use only in pregnancy/lactation if possible benefits outweigh potential risks)

Adverse Reactions/Side Effects

CNS: drowsiness, dizziness, confusion, headache, irritability, nervousness.

GI: nausea, anorexia, dry mouth, GI upset, vomiting.

GU: urinary retention.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug
CNS depression with other CNS depressants including alcohol, antihistamines, opioid analgesics, and sedative/hypnotics

Drug-Natural Products
Concomitant use of kava, valerian,or chamomile can CNS depression

Route/Dosage

• PO (Adults): 800 mg 3–4 times daily.

Availability

• Tablets: 800 mg

» Cost: $299.97/100.

Assessment

• Assess patient for pain, muscle stiffness, and range of motion before and periodically during therapy

• Geri: Assess geriatric patients for anticholinergic effects (sedation and weakness)

Lab Test Considerations

• Monitor hepatic function tests closely in patients with pre-existing liver damage

» May cause false-positive Benedict's tests

Potential Nursing Diagnoses

• Acute pain (Indications)

• Impaired bed mobility (Indications)

• Risk for injury (Side Effects)

Implementation

• Provide safety measures as indicated. Supervise ambulation and transfer of patients

• PO: Administer 3–4 times daily

Patient/Family Teaching

• Instruct patient to take medication as directed. Take missed doses within 1 hr; if not, return to regular dosing schedule. Do not double doses

• Encourage patient to comply with additional therapies prescribed for muscle spasm (rest, physical therapy, heat)

• Medication may cause dizziness, drowsiness, and blurred vision. Advise patient to avoid driving and other activities requiring alertness until response to drug is known

• Instruct patient to make position changes slowly to minimize orthostatic hypotension

• Advise patient to avoid concurrent use of alcohol and other CNS depressants while taking this medication

• Instruct patient to notify health care professional if skin rash or yellowish discoloration of the skin or eyes occurs

• Emphasize the importance of routine follow-up exams to monitor progress

Evaluation/Desired Outcomes

Decreased musculoskeletal pain and muscle spasticity

» Increased range of motion

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