Cyclobenzaprine Hydrochloride

Indications

Cyclobenzaprine Hydrochloride is used for: Fibromyalgia, Muscle spasm

Adult Dose

Oral Painful muscle spasm associated with musculoskeletal conditions Adult: 5 mg tid, may increase to 10 mg tid if needed. Treatment should not last more than 2-3 wk. Max: 60 mg. Elderly: Initiate with 5 mg with less frequent dosing. Max Dosage: 60 mg. Hepatic impairment: MIld: Start with 5 mg dose with less frequent dosing. Moderate to severe: Not recommended.

Child Dose

Muscle Spasm Oral <15 years: Safety and efficacy not established >15 years: 5 mg PO q8hr; may increase dose to 10 mg PO q8hr PRN

Renal Dose

Administration

Contra Indications

Recent MI, arrhythmias, severe liver disease.

Precautions

Cardiac disease, history of epilepsy, hepatic impairment, hyperthyroidism, pheochromocytoma, history of mania, psychoses, close-angle glaucoma, history of urinary retention, concurrent electroconvulsive therapy, diabetes. Pregnancy and lactation; elderly, child. Unsafe for use in patients with porphyria. Avoid abrupt withdrawal. May cause drowsiness; do not drive or operate machinery. Treatment for more than 2-3 wk is not recommended. Lactation: Excretion in milk unknown; use with caution

Pregnancy-Lactation

Pregnancy Available data from case reports with use in pregnancy have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes Lactation There are no data on presence of drug in either human or animal milk, the effects on a breastfed infant, or effects on milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed child from therapy or from underlying maternal condition.

Interactions

Plasma concentration may be increased with the use of cimetidine, diltiazem, disulfiram, methylphenidate, ritonavir, and verapamil. Side-effects are increased by adrenaline, amiodarone, general anesthetics, SSRIs, antihistamines, antimuscarinics, antipsychotics, anxiolytics and hypnotics, clozapine, disopyramide, diuretics, flecainide, MAOIs, moclobemide, moxifloxacin, nefopam, nicorandil, noradrenaline, phenothiazine, pimozide, procainamide, propafenone, quinidine, selegiline, sibutramine, sotalol, terfenadine, thioridazine, and tramadol. Effects of adrenergic neurone blockers, clonidine, barbiturates, nitrates, and primidone are reduced while effects of baclofen, opioid analgesics, and thyroid hormones are enhanced with concomitant use of cyclobenzaprine. Carbamazepine and rifampicin may increase metabolism of cyclobenzaprine. Effects may be antagonized by oestrogens. Avoid use with brimonidine, entacapone, artemether with lumefantrine, or sibutramine. CNS effects may be enhanced by other CNS depressants.

Adverse Effects

Side effects of Cyclobenzaprine Hydrochloride : >10% Drowsiness (up to 39% immediate-release), Dry mouth (21-32%), Dizziness (3-11%) 1-10% Pharyngitis (1-3%), Headache (1-5%), Fatigue (6%), Palpitations (6%), Bad taste in mouth (1-6%), Indigestion (4%), Blurred vision (3%), Constipation (1-3%), Asthenia (1-3%), Confusion (1-3%), Nausea (1-3%), Nervousness (1-3%) <1% Arrhythmia, Hypotension, Palpitation, Syncope, Tachycardia, Vasodilation, Cardiac dysrhythmia (rare), Cholestasis (rare), Hepatitis, Jaundice, Anaphylaxis (rare), Immune hypersensitivity reaction

Mechanism of Action

Cyclobenzaprine, a centrally-acting skeletal muscle relaxant, is structurally related to tricyclic antidepressants, thus they share similar properties. It acts on the brain stem, decreasing tonic-somatic motor activities influencing both the ? and ? motor systems. It is used as an adjunct in the symptomatic treatment of painful muscle spasms associated with musculoskeletal conditions.