Flexeril

DRUG DESCRIPTION

Cyclobenzaprine hydrochloride is a white, crystalline tricyclic amine salt with the empirical formula C20H21N•HCl and a molecular weight of 311.9. It has a melting point of 217#C, and a pKa of 8.47 at 25#C. It is freely soluble in water and alcohol, sparingly soluble in isopropanol, and insoluble in hydrocarbon solvents. If aqueous solutions are made alkaline, the free base separates. Cyclobenzaprine HCl is designated chemically as 3-(5H -dibenzo[a,d] cyclohepten-5-ylidene)-N, N-dimethyl-1-propanamine hydrochloride, and has the following structural formula:

FLEXERIL (cyclobenzaprine hydrochloride) Structural Formula Illustration

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.

FLEXERIL 5 mg (Cyclobenzaprine HCl) tablets contain the following inactive ingredients: hydroxypropyl cellulose, hypromellose, lactose, magnesium stearate, starch, titanium dioxide, Yellow D&C #10 Aluminum Lake HT, and Yellow FD&C #6 Aluminum Lake.

FLEXERIL 10 mg (Cyclobenzaprine HCl) tablets contain the following inactive ingredients: hydroxypropyl cellulose, hypromellose, iron oxide, lactose, magnesium stearate, starch, and titanium dioxide.

What are the possible side effects of cyclobenzaprine (Amrix, Comfort Pac with Cyclobenzaprine, Fexmid, Flexeril)?

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.

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

  • fast, pounding, or uneven heartbeats;
  • chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling;
  • sudden numbness or weakness, especially on one...

Read All Potential Side Effects and See Pictures of Flexeril »

What are the precautions when taking cyclobenzaprine hcl (Flexeril)?

Before taking cyclobenzaprine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: overactive thyroid (hyperthyroidism), irregular heartbeats (arrhythmia), other heart problems (congestive heart failure, heart block or conduction disorders), recent heart attack, moderate or severe liver disease.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: severe difficulty urinating (urinary retention),...

Read All Potential Precautions of Flexeril »


Flexeril Consumer (continued)

SIDE EFFECTS: Drowsiness, dry mouth, fatigue, dizziness, lightheadedness, constipation or blurred vision may occur as your body adjusts to the medication. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: mental/mood changes (e.g., confusion, hallucinations), difficulty urinating.

Tell your doctor immediately if any of these highly unlikely but very serious side effects occur: fast/pounding/irregular heartbeat, fainting, yellowing of the eyes/skin, stomach/abdominal pain, persistent nausea/vomiting/lack of appetite, dark urine, seizures, loss of coordination.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking cyclobenzaprine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: overactive thyroid (hyperthyroidism), irregular heartbeats (arrhythmia), other heart problems (congestive heart failure, heart block or conduction disorders), recent heart attack, moderate or severe liver disease.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: severe difficulty urinating (urinary retention), glaucoma, mild liver disease.

This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position.

Caution is advised when using this drug in the elderly because they may be more sensitive to its side effects, especially drowsiness, mental/mood changes, and possibly heart problems which could lead to a fall.

This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.

Based on information for similar drugs, cyclobenzaprine may pass into breast milk. Therefore, consult your doctor before breast-feeding.


Flexeril Patient Information Including Side Effects

Brand Names: Amrix, Comfort Pac with Cyclobenzaprine, Fexmid, Flexeril

Generic Name: cyclobenzaprine (Pronunciation: sye kloe BEN za preen)

  • What is cyclobenzaprine (Flexeril)?
  • What are the possible side effects of cyclobenzaprine (Flexeril)?
  • What is the most important information I should know about cyclobenzaprine (Flexeril)?
  • What should I discuss with my doctor before taking cyclobenzaprine (Flexeril)?
  • How should I take cyclobenzaprine (Flexeril)?
  • What happens if I miss a dose (Flexeril)?
  • What happens if I overdose (Flexeril)?
  • What should I avoid while taking cyclobenzaprine (Flexeril)?
  • What other drugs will affect cyclobenzaprine (Flexeril)?
  • Where can I get more information?

What is cyclobenzaprine (Flexeril)?

Cyclobenzaprine is a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain.

Cyclobenzaprine is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.

Cyclobenzaprine may also be used for other purposes not listed in this medication guide.

What are the possible side effects of cyclobenzaprine (Flexeril)?

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.

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

  • fast, pounding, or uneven heartbeats;
  • chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling;
  • sudden numbness or weakness, especially on one side of the body;
  • sudden headache, confusion, problems with vision, speech, or balance;
  • feeling light-headed, fainting;
  • confusion, weakness, lack of coordination;
  • nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • seizure (convulsions);
  • unusual thoughts or behavior, hallucinations (seeing things); or
  • easy bruising or bleeding, unusual weakness.

Less serious side effects may include:

  • dry mouth or throat;
  • blurred vision;
  • drowsiness, dizziness, tired feeling;
  • loss of appetite, stomach pain, nausea;
  • diarrhea, constipation, gas; or
  • muscle weakness.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about cyclobenzaprine (Flexeril)?

Do not take cyclobenzaprine if you have used an MAO inhibitor such as isocarboxazid (Marplan), tranylcypromine (Parnate), phenelzine (Nardil), or selegiline (Eldepryl, Emsam) within the past 14 days. Serious, life-threatening side effects can occur if you take cyclobenzaprine before the MAO inhibitor has cleared from your body.

You should not take cyclobenzaprine if you have recently had a heart attack, or if you have a heart rhythm disorder, congestive heart failure, heart block, or an overactive thyroid.

Cyclobenzaprine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Avoid drinking alcohol, which can increase some of the side effects of cyclobenzaprine.

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