Incidence of most common adverse reactions in the 2 double-blind*, placebo-controlled 5 mg studies (incidence of > 3% on cyclobenzaprine hydrochloride 5 mg):
*Note: Cyclobenzaprine hydrochloride10 mg data are from one clinical trial. cyclobenzaprine hydrochloride 5 mg and placebo data are from two studies. | |||
| Cyclobenzaprine hydrochloride 5 mg | Cyclobenzaprine hydrochloride 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 10 mg in additional controlled clinical studies, 7607 patients in the postmarketing 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 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:
| Clinical Studies With cyclobenzaprine hydrochloride 10 mg | Surveillance Program With cyclobenzaprine hydrochloride 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 under circ*mstances 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.
