CYCLOBENZAPRINE HYDROCHLORIDE

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. 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 hydrochloride is designated chemically as 3-(5H-dibenzo [a,d] cyclohepten-5-ylidene)-N,N-dimethyl-1-propanamine hydrochloride, and has the following structural formula: Each 5 mg Cyclobenzaprine hydrochloride tablet for oral administration contains 5 mg Cyclobenzaprine hydrochloride. Each 10 mg Cyclobenzaprine hydrochloride tablet for oral administration contains 10 mg Cyclobenzaprine hydrochloride. Each tablet contains the following inactive ingredients: lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, silicon dioxide, magnesium stearate, carnauba wax, titanium dioxide, polyethylene glycol, and iron oxide yellow. In addition, 5 mg tablets also contain polyvinyl alcohol, talc, lecithin, and FD&C yellow # 6 / sunset yellow FCF aluminum lake. In addition, 10 mg tablets also contain D&C yellow # 10 aluminum lake, FD&C yellow # 6 aluminum lake and hypromellose. chemical structure

Cyclobenzaprine hydrochloride tablets, USP 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. Cyclobenzaprine hydrochloride tablets, USP 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. Cyclobenzaprine hydrochloride tablets, USP have not been found effective in the treatment of spasticity associated with cerebral or spinal cord disease, or in children with cerebral palsy.

For most patients, the recommended dose of Cyclobenzaprine hydrochloride tablets, USP is 5 mg three times a day. Based on individual patient response, the dose may be increased to 10 mg three times a day. Use of Cyclobenzaprine hydrochloride tablets, USP for periods longer than two or three weeks is not recommended. (see INDICATIONS AND USAGE ). Less frequent dosing should be considered for hepatically impaired or elderly patients (see PRECAUTIONS, Impaired Hepatic Function , and PRECAUTIONS Use in the Elderly ).

Hypersensitivity to any component of this product. Concomitant use of monoamine oxidase (MAO) inhibitors or within 14 days after their discontinuation. Hyperpyretic crisis seizures and deaths have occurred in patients receiving cyclobenzaprine (or structurally similar tricyclic antidepressants) concomitantly with MAO inhibitor drugs. Acute recovery phase of myocardial infarction, and patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure. Hyperthyroidism.

Incidence of most common adverse reactions in the 2 double-blind‡, placebo-controlled 5 mg studies (incidence of > 3% on Cyclobenzaprine hydrochloride tablets, USP 5 mg): Cyclobenzaprinehydrochloride tablets, USP Cyclobenzaprinehydrochloride tablets, USP 5 mg 10 mg Placebo N=464 N=249 N=469 Drowsiness 29% 38% 10% Dry Mouth 21% 32% 7% Fatigue 6% 6% 3% Headache 5% 5% 8% 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. The following list of adverse reactions is based on the experience in 473 patients treated with Cyclobenzaprine hydrochloride tablets, USP 10 mg in additional controlled clinical studies, 7607 patients in the post-marketing surveillance program, and reports received since the drug was marketed. The overall incidence of adverse reactions among patients in the surveillance program was less than the incidence in the controlled clinical studies. The adverse reactions reported most frequently with Cyclobenzaprine hydrochloride tablets, USP 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: ‡ Note: Cyclobenzaprine hydrochloride tablets, USP 10 mg data are from one clinical trial. Cyclobenzaprine hydrochloride tablets, USP 5 mg and placebo data are from two studies . Clinical Studies With Cyclobenzaprinehydrochloride tablets, USP 10 mg Surveillance Program WithCyclobenzaprine hydrochloride tablets,USP 10 mg Drowsiness 39% 16% Dry Mouth 27% 7% Dizziness 11% 3% 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. 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: Body as a Whole: Syncope; malaise. Cardiovascular: Tachycardia; arrhythmia; vasodilatation; palpitation; hypotension. Digestive: Vomiting; anorexia; diarrhea; gastrointestinal pain; gastritis; thirst; flatulence; edema of the tongue; abnormal liver function and rare reports of hepatitis, jaundice and cholestasis. Hypersensitivity: Anaphylaxis; angioedema; pruritus; facial edema; urticaria; rash. Musculoskeletal: Local weakness. 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, serotonin syndrome. Skin: Sweating. Special Senses: Ageusia; tinnitus. Urogenital: Urinary frequency and/or retention. Causal Relationship Unknown Other reactions, reported rarely for Cyclobenzaprine hydrochloride tablets, USP 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. Cardiovascular: Hypertension; myocardial infarction; heart block; stroke. Digestive: Paralytic ileus, tongue discoloration; stomatitis; parotid swelling. Endocrine: Inappropriate ADH syndrome. Hematic and Lymphatic: Purpura; bone marrow depression; leukopenia; eosinophilia; thrombocytopenia. Metabolic, Nutritional and Immune: Elevation and lowering of blood sugar levels; weight gain or loss. Musculoskeletal: Myalgia. 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. Respiratory: Dyspnea. Skin: Photosensitization; alopecia. Urogenital: Impaired urination; dilatation of urinary tract; impotence; testicular swelling; gynecomastia; breast enlargement; galactorrhea.