Flexeril

Flexeril Information

Brand Name: Flexeril

Generic Name: Cyclobenzaprine HCl

Flexeril is a muscle relaxant used to relieve the pain and stiffness of muscle spasms and discomfort due to strain and sprain.

Flexeril Indications

Flexeril (cyclobenzaprine HCl) is indicated as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions.

Improvement is manifested by relief of muscle spasm and its associated signs and symptoms, namely, pain, tenderness, limitation of motion, and restriction in activities of daily living.

Flexeril should be used only for short periods (up to two or three weeks) because adequate evidence of effectiveness for more prolonged use is not available and because muscle spasm associated with acute, painful musculoskeletal conditions is generally of short duration and specific therapy for longer periods is seldom warranted.

Flexeril has not been found effective in the treatment of spasticity associated with cerebral or spinal cord disease, or in children with cerebral palsy.

Flexeril Ingredients and Composition

How Does Flexeril Work?

Cyclobenzaprine HCl, the active ingredient in Flexeril, relieves skeletal muscle spasm of local origin without interfering with muscle function. It is ineffective in muscle spasm due to central nervous system disease.

Cyclobenzaprine reduced or abolished skeletal muscle hyperactivity in several animal models. Animal Flexeril studies indicate that cyclobenzaprine does not act at the neuromuscular junction or directly on skeletal muscle. Such studies wshow that cyclobenzaprine acts primarily within the central nervous system at brain stem as opposed to spinal cord levels, although its action on the latter may contribute to its overall skeletal muscle relaxant activity. Evidence suggests that the net effect of cyclobenzaprine is a reduction of tonic somatic motor activity, influencing both gamma (g) and alpha (a) motor systems.

Pharmacological Flexeril studies in animals showed a similarity between the effects of cyclobenzaprine and the structurally related tricyclic antidepressants, including reserpine antagonism, norepinephrine potentiation, potent peripheral and central anticholinergic effects, and sedation. Cyclobenzaprine caused slight to moderate increase in heart rate in animals.

Cyclobenzaprine, the active ingredient in Flexeril, is well absorbed after oral administration, but there is a large intersubject variation in plasma levels. Cyclobenzaprine is eliminated quite slowly with a half-life as long as one to three days. It is highly bound to plasma proteins, is extensively metabolized primarily to glucuronide-like conjugates, and is excreted primarily via the kidneys.

No significant effect on plasma levels or bioavailability of cyclobenzaprine HCl or aspirin was noted when single or multiple doses of the two drugs were administered concomitantly. Concomitant administration of cyclobenzaprine HCl and aspirin is usually well tolerated and no unexpected or serious clinical or laboratory adverse effects have been observed. No studies have been performed to indicate whether cyclobenzaprine HCl enhances the clinical effect of aspirin or other analgesics, or whether analgesics enhance the clinical effect of cyclobenzaprine HCl in acute musculoskeletal conditions.

How To Take Flexeril and Flexeril Dosage and Administration

The usual dosage of Flexeril is 10 mg 3 times a day, with a range of 20 to 40 mg a day in divided doses. Flexeril dosage should not exceed 60 mg a day. Use of Flexeril for periods longer than 2 or 3 weeks is not recommended.

Take this medication with food to avoid stomach upset.

If you suspect a Flexeril Overdose

Flexeril Overdose Manifestations

High Flexeril doses may cause temporary confusion, disturbed concentration, transient visual hallucinations, agitation, hyperactive reflexes, muscle rigidity, vomiting, or hyperpyrexia, in addition to anything listed under Side Effects. Based on the known pharmacologic actions of the drug, overdosage may cause drowsiness, hypothermia, tachycardia and other cardiac rhythm abnormalities such as bundle branch block, ECG evidence of impaired conduction, and congestive heart failure. Other manifestations may be dilated pupils, convulsions, severe hypotension, stupor, and coma.

The acute oral LD50 of cyclobenzaprine HCl is approximately 338 and 425 mg/kg in mice and rats, respectively.

Treatment

Treatment of Flexeril overdose is symptomatic and supportive. Empty the stomach as quickly as possible by emesis, followed by gastric lavage. After gastric lavage, activated charcoal may be administered. Twenty to 30 g of activated charcoal may be given every 4 to 6 hours during the first 24 to 48 hours after ingestion. An ECG should be taken and close monitoring of cardiac function must be instituted if there is any evidence of dysrhythmia. Maintenance of an open airway, adequate fluid intake, and regulation of body temperature are necessary.

The intravenous administration of 1-3 mg of physostigmine salicylate is reported to reverse symptoms of poisoning by atropine and other drugs with anticholinergic activity. Physostigmine may be helpful in the treatment of cyclobenzaprine overdose. Because physostigmine is rapidly metabolized, the dosage of physostigmine should be repeated as required, particularly if life-threatening signs such as arrhythmias, convulsions, and deep coma recur or persist after the initial dosage of physostigmine. Because physostigmine itself may be toxic, it is not recommended for routine use.

Standard medical measures should be used to manage circulatory shock and metabolic acidosis due to Flexeril overdose. Cardiac arrhythmias may be treated with neostigmine, pyridostigmine, or propranolol. When signs of cardiac failure occur, the use of a short-acting digitalis preparation should be considered. Close monitoring of cardiac function for not less than five days is advisable.

Anticonvulsants may be given to control seizures.

Dialysis is probably of no value because of low plasma concentrations of the drug.

Since Flexeril overdosage is often deliberate, patients may attempt suicide by other means during the recovery phase. Deaths by deliberate or accidental overdosage have occurred with Flexeril.

Flexeril Pill Identification / ID and Appearance

Flexeril tablets are "D"-shaped, film coated tablets. 10 mg Tablets: Butterscotch yellow colored, with code "156" one one side and "WPPh" on the other.

Flexeril Side Effects

Flexeril Warnings

Flexeril Precautions and Contraindications

General

Because of its atropine-like action, Flexeril should be used with caution in patients with a history of urinary retention, angle-closure glaucoma, increased intraocular pressure, and in patients taking anticholinergic medication.

Information for the Patient

Flexeril may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle.

Contraindications to Flexeril

Hypersensitivity to Flexeril or any of its ingredients
Concomitant use of monoamine oxidase inhibitors or within 14 days after their discontinuation.
Acute recovery phase of myocardial infarction, and patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure.
Hyperthyroidism