General

Pronunciation
or-FENN-a-dreen

Trade Name(s)

• Antiflex

• Banflex

• Disipal [Canada]

• Flexoject

• Flexon

• Mio-Rel

• Myolin

• Myotrol

• Norflex

• Orfro

• Orphenate

Pregnancy Category
Category C

Ther. class.
skeletal muscle relaxants
(centrally acting)

Pharm. class.
diphenhydramine analogues

Indications

• Adjunct to rest and physical therapy in the treatment of muscle spasm associated with acute painful musculoskeletal conditions

• Adjunct therapy of Parkinson's disease (Canadian labeling only)

Action

Skeletal muscle relaxation, probably due to CNS depression

Therapeutic Effect(s):
Skeletal muscle relaxation, with decreased discomfort

Pharmacokinetics

Absorption: Readily absorbed after oral and IM administration; IV administration results in complete bioavailability

Distribution: Unknown

Metabolism and Excretion: Mostly metabolized by the liver

Half-life: 14 hr

TIME/ACTION PROFILE (skeletal muscle effects)

ROUTE	ONSET	PEAK	DURATION
PO-ER	within 1 hr	6–8 hr	12 hr
IM	5 min	30 min	12 hr
IV	immediate	unknown	12 hr

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity

• Bladder neck obstruction, prostatic hyperplasia, glaucoma, myasthenia gravis, peptic ulcer disease, GI obstruction

Use Cautiously in:

• Underlying cardiovascular disease

• Impaired renal function

• Geri: Appears on Beers list. Geriatric patients are more susceptible to sedation and anticholinergic effects

• OB: Pregnancy, lactation, or children (safety not established)

Adverse Reactions/Side Effects

CNS: CNS excitation, confusion, dizziness, drowsiness.

EENT: blurred vision, dry eyes.

CV: orthostatic hypotension, tachycardia.

GI: constipation, dry mouth.

GU: urinary retention.

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

Interactions

Drug-Drug

• Concurrent use of other anticholinergics risk of anticholinergic side effects

• risk of CNS depression with other CNS depressants including alcohol, antihistamines, antidepressants, sedative/hypnotics, or opioid analgesics

Drug-Natural Products
Kava, valerian, chamomile, or hops can CNS depression

Route/Dosage

Skeletal muscle relaxation

• PO (Adults): 100 mg twice daily.

• IV, IM (Adults): 60 mg q 12 hr.

Adjunctive therapy of Parkinson's disease

• PO (Adults): 50 mg 3 times daily (lower doses if used with other agents).

Availability

• Tablets: 50 mg^OTC[canada]

• Extended-release tablets: 100 mg

• Injection: 30 mg/ml

Assessment

• Geri: Assess geriatric patients for anticholinergic adverse effects (delirium, acute confusion, dizziness, dry mouth, blurred vision, urinary retention, constipation, tachycardia) and sedation

Skeletal Muscle Relaxant

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

Parkinson's Disease

• Assess parkinsonian and extrapyramidal symptoms (restlessness or desire to keep moving, rigidity, tremors, pill rolling, mask-like face, shuffling gait, muscle spasms, twisting motions, difficulty speaking or swallowing, loss of balance control) prior to and throughout therapy

Lab Test Considerations

• Monitor CBC and renal and hepatic function tests periodically during prolonged therapy

Potential Nursing Diagnoses

• Acute pain (Indications)

• Impaired physical mobility (Indications)

• Risk for injury (Side Effects)

Implementation

• Do not confuse Norflex (orphenadrine) with norfloxacin (Noroxin)

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

• PO: Do not break, crush or chew extended-release tablets

IV Adminstration:

• Direct IV:
May be administered undiluted

• Concentration:
30 mg/ml.

Patient/Family Teaching

• Advise 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

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

Evaluation/Desired Outcomes

• Decreased musculoskeletal pain and muscle spasticity

» Increased range of motion

• Decrease in tremors and rigidity and an improvement in gait and balance

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