cyclobenzaprine hydrochloride

cy·clo·ben·za·prine hydrochloride (skl-bnz-prn, skl-)

n.

A skeletal muscle relaxant used to relieve acute muscular spasms.

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cyclobenzaprine hydrochloride

[sī′kləben′zəprēn]

a muscle relaxant.

indication It is prescribed in the short-term treatment of muscle spasm.

contraindications Hyperthyroidism, cardiac arrhythmia, cardiac failure, concomitant use of a monoamine oxidase inhibitor, or known hypersensitivity to this drug prohibits its use. It is used with caution in conditions in which anticholinergics are contraindicated.

adverse effects The most serious adverse effects are hypersensitivity reactions. Drowsiness, dry mouth, and dizziness commonly occur.

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cyclobenzaprine hydrochloride

Apo-Cyclobenzaprine (CA), Amrix, Flexeril, Novo-Cycloprine (CA)

Pharmacologic class: Autonomic nervous system drug

Therapeutic class: Skeletal muscle relaxant (centrally acting)

Pregnancy risk category B

Action

Unclear. Thought to act primarily at brain stem (and to a lesser extent at spinal cord level) to relieve skeletal muscle spasms of local origin without altering muscle function.

Availability

Capsules (extended-release): 15 mg, 30 mg

Tablets: 5 mg, 10 mg

⊘Indications and dosages

➣ Adjunct to rest and physical therapy to relieve muscle spasm associated with acute, painful musculoskeletal conditions

Adults: 5 mg P.O. t.i.d. (immediate-release tablet). May increase to 10 mg P.O. t.i.d. (immediate-release tablet) as needed. Or, 15 mg (extended-release capsule) P.O. daily; some patients may need up to 30 mg/day, given as one 30-mg (extended-release capsule) P.O. daily or two 15-mg (extended-release capsules) P.O. daily.

Contraindications

• Hypersensitivity to drug
• Acute recovery phase after myocardial infarction (MI)
• Heart failure
• Arrhythmias
• Hyperthyroidism
• MAO inhibitor use within past 14 days

Precautions

Use cautiously in:
• cardiovascular disease, closed-angle glaucoma, hepatic impairment, increased intraocular pressure, urinary retention
• elderly patients
• pregnant or breastfeeding patients
• children younger than age 15.

Administration

☞ Don't give within 14 days of MAO inhibitor. Drug interaction may cause hypertensive crisis and severe seizures.
• Give extended-release capsule at approximately the same time each day.
• Know that drug shouldn't be used for more than 3 weeks.
• Be aware that drug may not be first-line agent for elderly patients because of its anticholinergic effects.

Route	Onset	Peak	Duration
P.O.	1 hr	4-6 hr	12-24 hr

Adverse reactions

CNS: dizziness, drowsiness, syncope, confusion, fatigue, headache, nervousness, decreased mental acuity, irritability, weakness, insomnia, depression, disorientation, delusions, peripheral neuropathy, abnormal gait, Bell's palsy, EEG changes, extrapyramidal symptoms, cerebrovascular accident

CV: vasodilation, tachycardia, chest pain, hypotension, MI, heart block

EENT: blurred vision

GI: nausea, constipation, dyspepsia, swollen parotid glands, mouth inflammation, discolored tongue, dry mouth, paralytic ileus

GU: galactorrhea, urinary retention, urinary frequency, gynecomastia, testicular swelling, libido changes, erectile dysfunction

Hematologic: purpura, eosinophilia, bone marrow depression, leukopenia, thrombocytopenia

Metabolic: hyperglycemia, hypoglycemia , syndrome of inappropriate diuretic hormone secretion

Musculoskeletal: muscle ache

Respiratory: dyspnea

Skin: photosensitization, alopecia, angioedema

Other: unpleasant taste, weight gain or loss, edema

Interactions

Drug-drug. Anticholinergics, anticholinergic-like drugs (including antidepressants, antihistamines, disopyramide, haloperidol, phenothiazines): additive anticholinergic effects

Antihistamines, CNS depressants, opioids, sedative-hypnotics: additive CNS depression

Guanadrel, guanethidine: reduction in or blockage of these drugs' actions

MAO inhibitors: hyperpyretic crisis, seizures, death

Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Drug-behaviors. Alcohol use: increased CNS depression

Patient monitoring

• Assess for adverse CNS effects, such as drowsiness, dizziness, and decreased mental acuity.
• Monitor patient for evidence of drug interactions, especially when giving drug with CNS depressants.

Patient teaching

• Tell patient to take extended-release capsule at approximately the same time each day.
• Tell patient that drug may cause dry mouth.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, alertness, and vision.
• Advise patient not to use alcohol, sedatives, pain medications, over-the-counter preparations, or herbs without consulting prescriber.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, herbs, and behaviors mentioned above.