Cyclobenzaprine

Relief of muscle spasm associated with acute painful musculoskeletal conditions, alongside rest and physical therapy. Use for only 2–3 weeks because prolonged effectiveness is not established and these conditions generally resolve over this interval.

Not effective for spasticity from brain/spinal-cord disease or in children with cerebral palsy. IR safety/effectiveness below 15 years is not established; ER pediatric safety/effectiveness has not been studied. This profile supplies adult regimens and does not endorse chronic pain, insomnia, antidepressant or pediatric off-label treatment.

Swallow intact, or sprinkle all capsule contents onto one tablespoon of applesauce and consume immediately without chewing. Rinse the mouth to ensure all contents are swallowed; discard unused mixture. Other foods have not been tested. Do not crush beads or divide the capsule contents into doses.

IR: in older adults or mild hepatic impairment, start at 5 mg and titrate slowly; less frequent dosing may be appropriate. IR is not recommended in moderate/severe hepatic impairment. Amrix ER is not recommended in older adults or any hepatic impairment because exposure increases and dosing flexibility is limited. Selected labels do not provide a numeric renal-adjustment schedule; assess the whole clinical situation rather than inventing one.

Hypersensitivity; MAOI use or within 14 days after stopping an MAOI; acute recovery from myocardial infarction; arrhythmias, heart block/conduction disturbances or congestive HF; and hyperthyroidism. MAOI combinations have caused severe hyperpyretic crises, seizures and deaths.

No boxed warning is present in the selected IR and Amrix ER labels. Serious MAOI, cardiac and serotonin risks remain prominent contraindications/warnings.

Drowsiness, dry mouth, dizziness, fatigue, constipation, nausea and dyspepsia are reported; older adults may develop confusion. Serious reports include arrhythmias, seizures, hypersensitivity and serotonin syndrome. Overdose can rapidly cause conduction changes, severe arrhythmia, coma or cardiac arrest and requires emergency toxicology assessment with ECG/airway monitoring. Do not attempt home decontamination or antidote treatment.

Available pregnancy case reports have not identified a clear developmental signal, but human data are limited; weigh clinical need rather than claiming safety. The selected ER label lacks milk-concentration, infant-effect and milk-production data; IR labeling similarly states human milk excretion is unknown and notes related TCAs enter milk. These are limitations of selected product labeling, not a claim that no newer lactation research exists.

IR safety/effectiveness below 15 years is not established. ER has not been studied in pediatric patients. Older adults have greater exposure and susceptibility to CNS/cardiac effects; use IR only when clearly needed with a cautious 5 mg start and slow titration/less frequent dosing. Amrix ER is not recommended in older adults.

Mild hepatic impairment increases IR exposure; start cautiously at 5 mg. IR moderate/severe hepatic use is not recommended; ER is not recommended in any hepatic impairment. No numeric renal regimen is supplied by the selected labels. Urinary metabolite excretion does not establish that impaired renal function has no clinical relevance.

Acts primarily centrally at brain-stem levels, reducing tonic somatic motor activity; it does not act directly at skeletal muscle or neuromuscular junction. The precise mechanism is incompletely characterized.

Immediate release

Oral bioavailability approximately 33–55%; effective half-life ~18 hours (range 8–37). With three-times-daily dosing, accumulation reaches steady state in ~3–4 days.

Extended release

Peak concentrations ~7–8 hours; mean half-life ~32 hours in studied adults. Food increases exposure; avoid assuming identical absorption to IR.

Metabolism / elimination

Extensive CYP3A4/CYP1A2 metabolism, with CYP2D6 contribution; primarily urinary excretion of glucuronide metabolites.

Special populations

Exposure/elimination increase with older age and hepatic impairment, underpinning formulation-specific restrictions.

• Review contraindicated cardiac/thyroid disease, MAOI exposure and interacting medicines before treatment.
• Follow pain/spasm-related function, physical-therapy progress and treatment duration.
• Assess drowsiness, confusion, falls, urinary retention and bowel/ocular symptoms; reconsider treatment if poorly tolerated.
• Urgently evaluate palpitations, fainting, allergy or serotonin-syndrome symptoms; ECG monitoring is required in suspected overdose.

• Follow IR three-times-daily versus ER once-daily directions; use only for the prescribed short course.
• Avoid alcohol; do not drive or operate machinery until the response is known.
• Follow exact ER applesauce instructions and never chew beads or save a mixture.
• Tell the prescriber about all antidepressants, sedatives, glaucoma/urinary problems and liver disease. Report rapid/irregular heartbeat or severe allergy immediately.

Dosage form / strength

Film-coated immediate-release tablet · 5 mg

Labeler

Teva Pharmaceuticals USA, Inc.

Appearance / imprint

White, round · W51 / TV

Example NDC

0093-3420-01 · 100 tablets

Selected Teva IR tablets: 5, 7.5 and 10 mg. Amrix ER capsules: 15 and 30 mg; 15 mg is orange/orange with blue imprint, and 30 mg is blue/red with white imprint. Other manufacturers may have different appearance and excipients; confirm the package.

Teva IR: 20–25°C in a well-closed container with child-resistant closure. Amrix ER: 25°C, excursions 15–30°C, in a tight light-resistant container. Consume a sprinkled applesauce dose immediately and discard any unused mixture; keep all medicine out of children’s reach.