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Flexeril (Cyclobenzaprine Hcl) Side Effects, Interactions, Warning


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10.22.2017 | Jennifer Bargeman
Cyclobenzaprine
Flexeril (Cyclobenzaprine Hcl) Side Effects, Interactions, Warning

Respiratory: Dyspnea. Nervous System and Psychiatric: Decreased or increased libido ; abnormal gait ; delusions; aggressive behavior; paranoia; peripheral neuropathy ; Bell's palsy ; alteration in EEG patterns; extrapyramidal symptoms.

FLEXERIL 5 mg tablets also contain Yellow D&C #10 Aluminum Lake HT, and Yellow FD&C #6 Aluminum Lake. FLEXERIL tablets contain the following inactive ingredients: hydroxypropyl cellulose, hydroxypropyl methylcellulose, iron oxide, lactose, magnesium stearate, starch, and titanium dioxide.

Cyclobenzaprine is closely related to the tricyclic antidepressants, e.g., amitriptyline and imipramine. In short term studies for indications other than muscle spasm associated with acute musculoskeletal conditions, and usually at doses somewhat greater than those recommended for skeletal muscle spasm, some of the more serious central nervous system reactions noted with the tricyclic antidepressants have occurred (see WARNINGS, below, and ADVERSE REACTIONS ).

Cyclobenzaprine is eliminated quite slowly, with an effective half-life of 18 hours (range 8-37 hours; n=18); plasma clearance is 0.7 L/min. Cyclobenzaprine is extensively metabolized, and is excreted primarily as glucuronides via the kidney. Cytochromes P-450 3A4, 1A2, and, to a lesser extent, 2D6, mediate N-demethylation, one of the oxidative pathways for cyclobenzaprine.

Skin: Sweating. Nervous System and Psychiatric: Seizures, ataxia ; vertigo ; dysarthria ; tremors; hypertonia ; convulsions; muscle twitching ; disorientation; insomnia; depressed mood; abnormal sensations; anxiety; agitation; psychosis, abnormal thinking and dreaming; hallucinations; excitement; paresthesia ; diplopia.

Other reactions, reported rarely for FLEXERIL under circumstances where a causal relationship could not be established or reported for other tricyclic drugs, are listed to serve as alerting information to physicians:

Body as a whole: Chest pain; edema.

Cyclobenzaprine did not affect the onset, incidence or distribution of neoplasia in an 81-week study in the mouse or in a 105-week study in the rat.

The adverse reactions reported most frequently with FLEXERIL were drowsiness, dry mouth and dizziness. The incidence of these common adverse reactions was lower in the surveillance program than in the controlled clinical studies:.

home drugs a-z list side effects drug center flexeril (cyclobenzaprine hcl) drug.

FLEXERIL 5 mg N=464 FLEXERIL 10 mg N=249 Placebo N=469 Drowsiness 29% 38% 10% Dry Mouth 21% 32% 7% Fatigue 6% 6% 3% Headache 5% 5% 8%

Psychiatric referral may be appropriate. Since overdosage is often deliberate, patients may attempt suicide by other means during the recovery phase.

As management of overdose is complex and changing, it is recommended that the physician contact a poison control center for current information on treatment.

At oral doses of up to 10 times the human dose, cyclobenzaprine did not adversely affect the reproductive performance or fertility of male or female rats. Cyclobenzaprine did not demonstrate mutagenic activity in the male mouse at dose levels of up to 20 times the human dose.

Due to the lack of data in subjects with more severe hepatic insufficiency, the use of FLEXERIL in subjects with moderate to severe impairment is not recommended. FLEXERIL should be used with caution in subjects with mild hepatic impairment starting with a 5 mg dose and titrating slowly upward. These patients are generally more susceptible to drugs with potentially sedating effects, including cyclobenzaprine.

FLEXERIL may enhance the effects of alcohol, barbiturates, and other CNS depressants.

Such studies show 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. Cyclobenzaprine reduced or abolished skeletal muscle hyperactivity in several animal models. Animal studies indicate that cyclobenzaprine does not act at the neuromuscular junction or directly on skeletal muscle. Evidence suggests that the net effect of cyclobenzaprine is a reduction of tonic somatic motor activity, influencing both gamma (γ) and alpha (α) motor systems.

FLEXERIL 5 mg (Cyclobenzaprine HCl) is supplied as a 5 mg tablet for oral administration. FLEXERIL 10 mg (Cyclobenzaprine HCl) is supplied as a 10 mg tablet for oral administration.

Digestive: Paralytic ileus, tongue discoloration; stomatitis; parotid swelling.

‡ Note: FLEXERIL 10 mg data are from one clinical trial. FLEXERIL 5 mg and placebo data are from two studies.

Acute recovery phase of myocardial infarction, and patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure. Hyperthyroidism.

The 5 mg tablets are yellow-orange, 5-sided, film coated tablets, coded FLEX over 5 on one side and without coding on the other. The two dosage strengths are supplied as follows:. The 10 mg tablets are butterscotch yellow, 5-sided D-shaped bi-convex, film coated tablets, coded FLEXERIL on one side and without coding on the other. FLEXERIL tablets are available in 5 mg and 10 mg dosage strengths.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

The following adverse reactions have been reported in post-marketing experience or with an incidence of less than 1% of patients in clinical trials with the 10 mg tablet:

5 mg 100 count bottle NDC 10 mg 100 count bottle NDC.

Dysrhythmias unresponsive to sodium bicarbonate therapy/hyperventilation may respond to lidocaine, bretylium or phenytoin. A pH > 7.60 or a pCO2 < 20 mmHg is undesirable. Serum alkalinization, to a pH of 7.45 to 7.55, using intravenous sodium bicarbonate and hyperventilation (as needed), should be instituted for patients with dysrhythmias and/or QRS widening. Type 1A and 1C antiarrhythmics are generally contraindicated (e.g., quinidine, disopyramide, and procainamide). A maximal limb-lead QRS duration of ≥ 0.10 seconds may be the best indication of the severity of the overdose.

Adverse reactions which were reported in 1% to 3% of the patients were: abdominal pain, acid regurgitation, constipation, diarrhea, dizziness, nausea, irritability, mental acuity decreased, nervousness, upper respiratory infection, and pharyngitis.

Among the less frequent adverse reactions, there was no appreciable difference in incidence in controlled clinical studies or in the surveillance program. Adverse reactions which were reported in 1% to 3% of the patients were: fatigue/tiredness, asthenia, nausea, constipation, dyspepsia, unpleasant taste, blurred vision, headache, nervousness, and confusion.

In a pharmacokinetic study in elderly individuals ( ≥ 65yrs old), mean (n=10) steady-state cyclobenzaprine AUC values were approximay 1.7 fold (171.0 ng.hr/mL, range 96.1-255.3) higher than those seen in a group of eighteen younger adults (101.4 ng.hr/mL, range 36.1-182.9) from another study. Elderly male subjects had the highest observed mean increase, approximay 2.4 fold (198.3 ng.hr/mL, range 155.6-255.3 versus 83.2 ng.hr/mL, range 41.1-142.5 for younger males) while levels in elderly females were increased to a much lesser extent, approximay 1.2 fold (143.8 ng.hr/mL, range 96.1-196.3 versus 115.9 ng.hr/mL, range 36.1-182.9 for younger females).

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

Urogenital: Urinary frequency and/or retention.

If aqueous solutions are made alkaline, the free base separates. It has a melting point of 217°C, and a pKa of 8.47 at 25°C. Cyclobenzaprine hydrochloride is a white, crystalline tricyclic amine salt with the empirical formula C 20 H 21 N•HCl and a molecular weight of 311.9. Cyclobenzaprine HCl is designated chemically as 3-(5H-dibenzo cyclohepten-5-ylidene)-N, Ndimethyl- 1-propanamine hydrochloride, and has the following structural formula:. It is freely soluble in water and alcohol, sparingly soluble in isopropanol, and insoluble in hydrocarbon solvents.

In rats treated with FLEXERIL for up to 67 weeks at doses of approximay 5 to 40 times the maximum recommended human dose, pale, sometimes enlarged, livers were noted and there was a dose-related hepatocyte vacuolation with lipidosis. In the higher dose groups this microscopic change was seen after 26 weeks and even earlier in rats which died prior to 26 weeks; at lower doses, the change was not seen until after 26 weeks.

Endocrine: Inappropriate ADH syndrome.

Signs and symptoms of toxicity may develop rapidly after cyclobenzaprine overdose; therefore, hospital monitoring is required as soon as possible. Multiple drug ingestion (including alcohol) is common in deliberate cyclobenzaprine overdose. The acute oral LD50 of FLEXERIL is approximay 338 and 425 mg/kg in mice and rats, respectively. Although rare, deaths may occur from overdosage with FLEXERIL. As management of overdose is complex and changing, it is recommended that the physician contact a poison control center for current information on treatment.

This should include large volume gastric lavage followed by activated charcoal. All patients suspected of an overdose with FLEXERIL should receive gastrointestinal decontamination. If consciousness is impaired, the airway should be secured prior to lavage and emesis is contraindicated.

Digestive: Vomiting; anorexia ; diarrhea; gastrointestinal pain; gastritis ; thirst; flatulence ; edema of the tongue; abnormal liver function and rare reports of hepatitis, jaundice and cholestasis.

The overall incidence of adverse reactions among patients in the surveillance program was less than the incidence in the controlled clinical studies. The following list of adverse reactions is based on the experience in 473 patients treated with FLEXERIL 10 mg in additional controlled clinical studies, 7607 patients in the post-marketing surveillance program, and reports received since the drug was marketed.

Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F).

Because cyclobenzaprine is closely related to the tricyclic antidepressants, some of which are known to be excreted in human milk, caution should be exercised when FLEXERIL is administered to a nursing woman. It is not known whether this drug is excreted in human milk.

Hypersensitivity to any component of this product.

Protect the patient's airway, establish an intravenous line and initiate gastric decontamination. Dialysis is probably of no value because of low plasma concentrations of the drug. Observation with cardiac monitoring and observation for signs of CNS or respiratory depression, hypotension, cardiac dysrhythmias and/or conduction blocks, and seizures is necessary. Monitoring of plasma drug levels should not guide management of the patient. If signs of toxicity occur at any time during this period, extended monitoring is required. In order to protect against the rare but potentially critical manifestations described above, obtain an ECG and immediay initiate cardiac monitoring.

ULTRAM (tramadol HCl tablets, Ortho- McNeil Pharmaceutical) ULTRACET (tramadol HCl and acetaminophen tablets, Ortho-McNeil Pharmaceutical).

Special Senses: Ageusia ; tinnitus.

Hyperpyretic crisis seizures, and deaths have occurred in patients receiving cyclobenzaprine (or structurally similar tricyclic antidepressants ) concomitantly with MAO inhibitor drugs. Concomitant use of monoamine oxidase (MAO) inhibitors or within 14 days after their discontinuation.

Skin: Photosensitization; alopecia.

Metabolic, Nutritional and Immune: Elevation and lowering of blood sugar levels; weight gain or loss. Musculoskeletal: Myalgia.

Stop using cyclobenzaprine and call your doctor at once if you have any of these serious side effects:

The plasma concentration of cyclobenzaprine is generally higher in the elderly and in patients with hepatic impairment. (See PRECAUTIONS, Use in the Elderly and PRECAUTIONS, Impaired Hepatic Function. ).

It is strongly recommended that the physician contact the local poison control center for specific pediatric treatment. The principles of management of child and adult overdosages are similar.

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.

Clinical Studies With FLEXERIL 10 mg Surveillance Program With FLEXERIL 10 mg Drowsiness 39% 16% Dry Mouth 27% 7% Dizziness 11% 3%

Hematic and Lymphatic: Purpura ; bone marrow depression; leukopenia ; eosinophilia ; thrombocytopenia.

Musculoskeletal: Local weakness. Hypersensitivity: Anaphylaxis ; angioedema ; pruritus ; facial edema; urticaria ; rash.

FLEXERIL (cyclobenzaprine HCl) Tablets.

Based on individual patient response, the dose may be increased to 10 mg three times a day. (see INDICATIONS AND USAGE ). Use of FLEXERIL for periods longer than two or three weeks is not recommended. For most patients, the recommended dose of FLEXERIL is 5 mg three times a day.

FLEXERIL may enhance the effects of alcohol, barbiturates, and other CNS depressants.

These are not indicative of addiction. Pharmacologic similarities among the tricyclic drugs require that certain withdrawal symptoms be considered when FLEXERIL is administered, even though they have not been reported to occur with this drug. Abrupt cessation of treatment after prolonged administration rarely may produce nausea, headache, and malaise.

FLEXERIL may have life-threatening interactions with MAO inhibitors. (See CONTRAINDICATIONS. ).

Body as a Whole: Syncope ; malaise.

Tricyclic antidepressants may enhance the seizure risk in patients taking tramadol.†

Tricyclic antidepressants may block the antihypertensive action of guanethidine and similarly acting compounds.

Fort Washington, PA 19034. Manufactured by: McNeil Consumer Healthcare. Titusville, NJ 08560. Edition: April 2013. Manufactured for: McNeil Pediatrics Division of Ortho-McNeil-Janssen Pharmaceuticals, Inc. Division of McNeil-PPC, Inc.

Urogenital: Impaired urination; dilatation of urinary tract ; impotence ; testicular swelling; gynecomastia ; breast enlargement; galactorrhea.

Pregnancy Category B : Reproduction studies have been performed in rats, mice and rabbits at doses up to 20 times the human dose, and have revealed no evidence of impaired fertility or harm to the fetus due to FLEXERIL. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. There are, however, no adequate and well-controlled studies in pregnant women.

Physostigmine is not recommended except to treat life-threatening symptoms that have been unresponsive to other therapies, and then only in close consultation with a poison control center. phenobarbital, phenytoin). In patients with CNS depression, early intubation is advised because of the potential for abrupt deterioration. Seizures should be controlled with benzodiazepines or, if these are ineffective, other anticonvulsants (e.g.

Other potential effects of overdosage include any of the symptoms listed under ADVERSE REACTIONS.

Pharmacological 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.

Cardiovascular: Hypertension ; myocardial infarction ; heart block ; stroke.

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.

The plasma concentration of cyclobenzaprine is increased in patients with hepatic impairment (see CLINICAL PHARMACOLOGY, Pharmacokinetics, Hepatic Impairment ).

It is highly bound to plasma proteins. Cyclobenzaprine exhibits linear pharmacokinetics over the dose range 2.5 mg to 10 mg, and is subject to enterohepatic circulation. At steady state in healthy subjects receiving 10 mg t.i.d. (n=18), peak plasma concentration was 25.9 ng/mL (range, 12.8-46.1 ng/mL), and area under the concentration-time (AUC) curve over an 8-hour dosing interval was 177 ng.hr/mL (range, 80-319 ng.hr/mL). Estimates of mean oral bioavailability of cyclobenzaprine range from 33% to 55%. Drug accumulates when dosed three times a day, reaching steady-state within 3-4 days at plasma concentrations about four-fold higher than after a single dose.

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

Safety and effectiveness of FLEXERIL in pediatric patients below 15 years of age have not been established.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

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.

Incidence of most common adverse reactions in the 2 double-blind‡, placebo-controlled 5 mg studies (incidence of > 3% on FLEXERIL 5 mg):

Less frequent manifestations include tremor, agitation, coma, ataxia, hypertension, slurred speech, confusion, dizziness, nausea, vomiting, and hallucinations. The most common effects associated with cyclobenzaprine overdose are drowsiness and tachycardia. Changes in the electrocardiogram, particularly in QRS axis or width, are clinically significant indicators of cyclobenzaprine toxicity. Rare but potentially critical manifestations of overdose are cardiac arrest, chest pain, cardiac dysrhythmias, severe hypotension, seizures, and neuroleptic malignant syndrome.

For these reasons, in the elderly, cyclobenzaprine should be used only if clearly needed. In such patients FLEXERIL should be initiated with a 5 mg dose and titrated slowly upward. The plasma concentration of cyclobenzaprine is increased in the elderly (see CLINICAL PHARMACOLOGY, Pharmacokinetics, Elderly ). The elderly may also be more at risk for CNS adverse events such as hallucinations and confusion, cardiac events resulting in falls or other sequelae, drug-drug and drug-disease interactions.

Tricyclic antidepressants have been reported to produce arrhythmias, sinus tachycardia, prolongation of the conduction time leading to myocardial infarction and stroke.

Less frequent dosing should be considered for hepatically impaired or elderly patients (see PRECAUTIONS, Impaired Hepatic Function, and Use in the Elderly ).

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In light of these findings, therapy with FLEXERIL in the elderly should be initiated with a 5 mg dose and titrated slowly upward.

Cardiovascular: Tachycardia ; arrhythmia ; vasodilatation; palpitation; hypotension.

Cyclobenzaprine