CYCLOBENZAPRINE

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.

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.

Cyclobenzaprine Interactions?
Many drugs can interact with cyclobenzaprine. Below is just a partial list. Tell your doctor if you are using:

• atropine (Donnatal, and others), benztropine (Cogentin), dimenhydrinate (Dramamine), methscopolamine (Pamine), or scopolamine (Transderm-Scop);
• a bronchodilator such as ipratroprium (Atrovent) or tiotropium (Spiriva);
• glycopyrrolate (Robinul);
• guanethidine (Ismelin);
• mepenzolate (Cantil);
• tramadol (Ultram);
• bladder or urinary medications such as darifenacin (Enablex), flavoxate (Urispas), oxybutynin (Ditropan, Oxytrol), tolterodine (Detrol), or solifenacin (Vesicare); or
• irritable bowel medications such as dicyclomine (Bentyl), hyoscyamine (Anaspaz, Cystospaz, Levsin, and others), or propantheline (Pro-Banthine).

This list is not complete and there may be other drugs that can interact with cyclobenzaprine. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.

Before taking cyclobenzaprine,

• tell your doctor and pharmacist if you are allergic to cyclobenzaprine or any other drugs.
• tell your doctor and pharmacist what prescription and nonprescription drugs you are taking or have taken within the last 2 weeks, especially medications for depression, seizures, allergies, coughs, or colds; MAO inhibitors (phenelzine [Nardil], tranylcypromine [Parnate]); sedatives; sleeping pills; tranquilizers; and vitamins.
• tell your doctor if you have an overactive thyroid gland, heart disease, glaucoma, or difficulty urinating.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking cyclobenzaprine, call your doctor immediately.
• talk to your doctor about the risks and benefits of taking cyclobenzaprine if you are 65 years of age or older. Older adults should not usually take cyclobenzaprine because it is not as safe or effective as other medications that can be used to treat the same condition.
• you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how cyclobenzaprine affects you.
• remember that alcohol can add to the drowsiness caused by this drug.

Cyclobenzaprine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• drowsiness
• dry mouth
• dizziness
• upset stomach

If you experience any of the following symptoms, call your doctor immediately:

• severe skin rash
• swelling of the face or tongue
• difficulty breathing or swallowing
• irregular heart rate
• chest pain
• fever
• seizures

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online or by phone [1-800-332-1088].

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.