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Cyclobenzaprine hydrochloride, USP is a white to off-white crystalline tricyclic amine salt powder, 1-Propanamine, 3-(5H-dibenzo[a,d] cyclohepten-5-ylidene)-N,N-dimethyl-, hydrochloride. The molecular formula is C20H21N • HCl and the molecular weight is 311.85 g/mol, and it has a pK of 6.8. It is freely soluble in water and pH independent. Cyclobenzaprine hydrochloride has the following chemical structure:
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Each sublingual tablet contains 2.8 mg of cyclobenzaprine hydrochloride (equivalent to 2.47 mg cyclobenzaprine) and the following inactive ingredients: colloidal silicon dioxide, corn starch, crospovidone (Type A), D&C Yellow No.10, dibasic potassium phosphate, mannitol, and sodium stearyl fumarate.
The following clinically significant reactions are described in greater detail, in other sections of this labeling:
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The safety of sublingual TONMYA (14 days of 2.8 mg once daily and then 5.6 mg once daily thereafter) is supported by three double-blind, placebo-controlled clinical trials (Trials 1, 2, and 3) in adult patients with fibromyalgia [see Clinical Studies (14)]. A total of 1,182 patients completed at least 14 weeks of daily treatment, including 580 TONMYA-treated patients (14 days of 2.8 mg once daily and then 5.6 mg once daily thereafter) and 602 placebo-treated patients.
Table 1 summarizes the most common adverse reactions in Trials 1, 2, and 3 (≥ 2% of TONMYA-treated patients and at a higher incidence in TONMYA-treated patients compared to placebo-treated patients).
Table 1: Adverse Reactions Reported in ≥ 2% of TONMYA-Treated Patients and a Higher Incidence than
Placebo-Treated Patients in Adult Patients with Fibromyalgia (Trials 1, 2, and 3)
| Adverse Reactions | Placebo (N = 739) |
TONMYA (N = 735) |
| Oral hypoesthesiaa | 0.7% | 23% |
| Oral discomfortb | 0.7% | 9% |
| Abnormal product taste | 0.7% | 9% |
| Somnolencec | 2% | 6% |
| Oral paresthesiad | 0.4% | 6% |
| Oral paine | 1% | 5% |
| Fatiguef | 2% | 4% |
| Dry mouthg | 2% | 3% |
| Aphthous ulcer | 0.5% | 2% |
| a Oral hypoesthesia includes hypoesthesia and teeth hypoesthesia b Oral discomfort includes tongue discomfort c Somnolence includes hypersomnia, lethargy, and sedation d Oral paresthesia includes paresthesia and teeth hyperesthesia e Oral pain includes glossodynia f Fatigue includes asthenia and lethargy g Dry mouth includes dry throat |
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In Trials 1, 2, and 3, 43% of TONMYA-treated patients compared to 8% of placebo-treated patients experienced at least 1 treatment-emergent oral mucosal adverse reaction. The most common oral mucosal adverse reactions included oral hypoesthesia, abnormal product taste, oral paresthesia, tongue discomfort, oral discomfort, glossodynia, oral pain, and aphthous ulcer. The majority (82%) of oral mucosal adverse reactions began within minutes of dosing, and of those, 88% occurred after nearly every dose. Almost two-thirds lasted less than 60 minutes. Of the approximately one-third that lasted longer than 60 minutes, 63% were present the next morning.
Five patients (0.7% of TONMYA-treated patients) experienced severe oral mucosal adverse reactions, including paresthesia, glossitis, hypoesthesia, oral pain, and dry mouth. Most reactions resolved within days after TONMYA was discontinued. Oral mucosal adverse reactions leading to discontinuation occurred more frequently in TONMYA-treated patients compared to placebo-treated patients (4.5% vs. 0.5%).
In an open-label, long-term 40 to 52-week safety trial (Trial 4) in an unapproved population of patients previously exposed to 5.6 mg TONMYA once daily (maximum recommended dosage) or placebo, 56 patients were treated with 5.6 mg of TONMYA for at least 1 year. The most common adverse reactions in the TONMYA-treated patients (>5%) were oral hypoesthesia (45%), somnolence (18%), abnormal product taste (7%), and paresthesia oral (7%).
In an open-label, long-term 52 week safety trial of adult patients with fibromyalgia previously been exposed to 2.8 mg TONMYA once daily (one half the recommended dosage [see Dosage and Administration (2.1)]) or placebo (Trial 5), 97 patients were treated for at least 1 year with 2.8 mg of TONMYA once daily. The most common adverse reactions (>5%) in the TONMYA-treated patients were hypoesthesia oral (15%), fatigue (7%), sinusitis (7%), and abnormal product taste (6%).
The following adverse reactions have been reported in clinical studies or postmarketing experience with cyclobenzaprine immediate-release (IR) products, cyclobenzaprine extended-release (ER) products, or TCAs. Because some of these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
In a postmarketing surveillance program of cyclobenzaprine IR products, the adverse reactions reported most frequently were drowsiness, dry mouth, and dizziness, and adverse reactions 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 postmarketing experience with cyclobenzaprine ER products or cyclobenzaprine IR products, in clinical studies of cyclobenzaprine IR products (incidence < 1%), or in postmarketing experience with other TCAs:
Body as a Whole: Syncope; malaise; chest pain; edema.
Cardiovascular: Tachycardia; arrhythmia; vasodilatation; palpitation; hypotension; hypertension; myocardial infarction; heart block; stroke.
Digestive: Vomiting; anorexia; diarrhea; gastrointestinal pain; gastritis; thirst; flatulence; edema of the tongue; abnormal liver function and rare reports of hepatitis, jaundice, and cholestasis; paralytic ileus, tongue discoloration; stomatitis; parotid swelling.
Endocrine: Inappropriate ADH syndrome.
Hematologic and Lymphatic: Purpura; bone marrow depression; leukopenia; eosinophilia; thrombocytopenia.
Hypersensitivity: Anaphylaxis; angioedema; pruritus; facial edema; urticaria; rash.
Metabolic, Nutritional, and Immune: Elevation and lowering of blood sugar levels; weight gain or loss.
Musculoskeletal: Local weakness; myalgia.
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; neuroleptic malignant syndrome; decreased or increased libido; abnormal gait; delusions; aggressive behavior; paranoia; peripheral neuropathy; Bell’s palsy; alteration in EEG patterns; extrapyramidal symptoms.
Respiratory: Dyspnea.
Skin: Sweating; photosensitization; alopecia.
Special Senses: Ageusia; tinnitus.
Urogenital: Urinary frequency and/or retention; impaired urination; dilatation of urinary tract; impotence; testicular swelling; gynecomastia; breast enlargement; galactorrhea.
Based on its structural similarity to TCAs, concomitant use of TONMYA with:
Postmarketing cases of serotonin syndrome have been reported with the concomitant use of oral cyclobenzaprine and other drugs, such as SSRIs, SNRIs, TCAs, tramadol, bupropion, meperidine, verapamil, or MAO inhibitors [see Warnings and Precautions (5.2)].
TONMYA contains cyclobenzaprine, which is not a controlled substance.
Given the pharmacologic similarities among the TCAs, consider withdrawal symptoms when stopping TONMYA. Abrupt cessation of TONMYA treatment after prolonged administration may produce nausea, headache, and malaise. These are not indicative of addiction.
Included as part of the PRECAUTIONS section.
Based on data from animal reproduction studies, TONMYA may cause an increased risk of neural tube defects when administered to a pregnant female two weeks prior to conception and during the first trimester of pregnancy. Neural tube defects (splayed vertebral arches and spina bifida occulta) were observed in a rabbit embryofetal development study at the highest maternal dose tested, in the absence of maternal toxicity. Because neural tube development occurs early in pregnancy, often before pregnancy is recognized, advise females of reproductive potential of the potential risk to the fetus and avoid use of TONMYA two weeks prior to conception and through the first trimester of pregnancy.
Perform a pregnancy test prior to initiation of treatment with TONMYA to exclude use of TONMYA during the first trimester of pregnancy.
Advise females of reproductive potential to use effective contraception during TONMYA treatment and for two weeks after the final dose [see Use in Specific Populations (8.1, 8.3)].
The development of a potentially life-threatening serotonin syndrome has been reported with cyclobenzaprine when used in combination with other drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or MAO inhibitors. The concomitant use of TONMYA with MAO inhibitors is contraindicated [see Contraindications (4)].
Serotonin syndrome symptoms may include mental status changes (e.g., confusion, agitation, hallucinations), autonomic instability (e.g., diaphoresis, tachycardia, labile blood pressure, hyperthermia), neuromuscular abnormalities (e.g., tremor, ataxia, hyperreflexia, clonus, muscle rigidity), and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea).
Treatment with TONMYA and any concomitant serotonergic agents should be discontinued immediately if serotonin syndrome symptoms occur and supportive symptomatic treatment should be initiated. If concomitant treatment with TONMYA and other serotonergic drugs is clinically warranted, careful observation is advised, particularly during treatment initiation or dosage increases.
Cyclobenzaprine is structurally related to tricyclic antidepressants (TCAs).
TCAs have been reported to produce arrhythmias, sinus tachycardia, prolongation of the conduction time leading to myocardial infarction and stroke [see Contraindications (4)].
Some of the more TCA-associated serious central nervous system (CNS) reactions have occurred in short-term studies of oral cyclobenzaprine. If clinically significant CNS symptoms develop, consider discontinuation of TONMYA.
Caution should be used when TCAs are given to patients with a history of seizure disorder, because TCAs may lower the seizure threshold. Patients with a history of seizures should be monitored during TCA use to identify recurrence of seizures or increase in frequency of seizures.
Because of its atropine-like action, TONMYA should be used with caution in patients with a history of urinary retention, angle-closure glaucoma, increased intraocular pressure, and in patients taking anticholinergic drugs.
TONMYA monotherapy may cause CNS depression and concomitant use of TONMYA with alcohol, barbiturates, or other CNS depressants may increase the risk of CNS depression [see Drug Interactions (7)].
Symptoms of CNS depression include somnolence. Advise patients not to operate a motor vehicle or dangerous machinery until they are reasonably certain that TONMYA therapy will not adversely affect their ability to engage in such activities.
Oral mucosal adverse reactions, including sensory changes (e.g., numbness, tingling), discomfort, pain, irritation, inflammation, and lesions, occurred more frequently in patients treated with TONMYA compared to placebo (43% vs. 8%) [see Adverse Reactions (6.1)]. Reactions typically occurred within minutes of administration and most resolved within 60 minutes.
Five patients experienced severe oral mucosal adverse reactions, including sensory changes (paresthesia, hypoesthesia), inflammation (glossitis), oral pain, and dry mouth. Most severe oral mucosal adverse reactions resolved within days after TONMYA was discontinued and no treatment was required.
Advise patients to moisten the mouth with sips of water before administration of TONMYA to reduce the risk of oral sensory changes (hypoesthesia). Advise patients to report severe oral mucosal adverse reactions to their healthcare provider. Consider discontinuation of TONMYA if severe reactions occur.
Long-term studies were conducted in CD-1 mice and Sprague-Dawley rats with oral cyclobenzaprine to evaluate its carcinogenic potential. In an 81-week carcinogenicity study, metastatic hemangiosarcoma was seen in 3 of 21 male mice at 10 mg/kg/day (approximately 9 times the maximum recommended human dose (MRHD) of 5.6 mg of TONMYA on a mg/m2 basis). In a 105-week carcinogenicity study, malignant astrocytoma was seen in 3 of 50 male rats at 10 mg/kg/day (approximately 0.3 times the MRHD on an estimated AUC basis). There were no tumor findings in female mice or rats.
Cyclobenzaprine was not mutagenic or clastogenic in the following assays: in vitro Ames bacterial mutation assays, an in vitro Chinese hamster ovary (CHO) cell chromosomal aberration test, an in vitro CHO cell micronucleus test, and in vivo mouse bone marrow micronucleus assays.
Cyclobenzaprine HCl, when administered 70 and 14 days prior to mating to male and female rats, respectively, had no effects on fertility or reproductive performance at oral doses up to 20 mg/kg/day (approximately 1.1 and 3.8 times in males and females, respectively, the MRHD on an estimated AUC basis).
In a 67-week study with rats that received cyclobenzaprine at oral doses of 10, 20, or 40 mg/kg/day (approximately 0.3 to 4.3 times and 1.2 to 12.4 times in males and females, respectively, the maximum recommended human dose (MRHD) of 5.6 mg of TONMYA on an estimated AUC basis), there were findings in the liver consisting of midzonal vacuolation with lipidosis for males and midzonal and centrilobular hepatocytic enlargement for females. In addition, there were findings of centrilobular coagulative necrosis. In the higher dose groups, these microscopic changes were seen after 26 weeks and even earlier in rats that died prior to 26 weeks; at lower doses, these changes were not seen until after 26 weeks.
In a 26-week study with Cynomolgus monkeys that received cyclobenzaprine at oral of doses of 2.5, 5, 10, or 20 mg/kg/day, one monkey at 20 mg/kg/day (69 times the MRHD on mg/m2 basis) was euthanized in week 17. Morbidity for this animal was attributed to findings of chronic pancreatitis, cholecystitis, cholangitis, and focal liver necrosis.
Changes in the electrocardiogram, particularly in QRS axis or width, are clinically significant indicators of cyclobenzaprine toxicity. Other potential cyclobenzaprine overdosage adverse reactions include any of the adverse reactions listed under Adverse Reactions (6).
Multiple drug ingestion (including alcohol) is common in deliberate cyclobenzaprine overdose.
Consider contacting the Poison Help line (1-800-222-1222) or a medical toxicologist for additional overdose management recommendations.
Signs and symptoms of toxicity may develop rapidly after cyclobenzaprine overdose; therefore, hospital monitoring is recommended as soon as possible. To reduce the risk of rare but potentially critical cyclobenzaprine overdose manifestations, obtain an ECG and immediately initiate cardiac monitoring. Protect the patient’s airway and establish an intravenous line. Recommend observation with cardiac monitoring and observation for signs of CNS or respiratory depression, hypotension, cardiac dysrhythmias and/or conduction blocks, and seizures.
Monitoring of plasma cyclobenzaprine levels should not guide overdose management of the patient. Dialysis is probably of no value because of low plasma concentrations of cyclobenzaprine.
Treatment of Cardiovascular Overdosage Complications: A maximal limb-lead QRS duration of 0.1 seconds may be the best indication of the severity of the cyclobenzaprine overdose.
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. A pH >7.6 or a pCO2 < 20 mmHg is undesirable. Dysrhythmias unresponsive to sodium bicarbonate therapy/hyperventilation may respond to lidocaine or phenytoin. Type 1A and 1C antiarrhythmics (e.g., quinidine, disopyramide, and procainamide) are generally contraindicated in the setting of a cyclobenzaprine overdose.
Treatment of CNS Overdosage Complications: In patients with CNS depression associated with a cyclobenzaprine overdose, 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., phenobarbital, phenytoin). 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 center.
The mechanism of action of cyclobenzaprine for the treatment of fibromyalgia in adults is unknown. In in vitro pharmacology studies, cyclobenzaprine demonstrated functional antagonism of 5-HT2A, α1-adrenergic, H1-histaminergic, and M1-muscarinic acetylcholine receptors. In addition, pharmacological studies in animals demonstrated a similarity between the effects of cyclobenzaprine and the structurally related TCAs, including reserpine antagonism, norepinephrine potentiation, potent peripheral and central anticholinergic effects, and sedation.
The exposure-response relationship and time course of pharmacodynamic response for the safety and effectiveness of cyclobenzaprine have not been fully characterized.
Following single-dose sublingual administration of 2.8 mg and 5.6 mg of TONMYA in healthy adult subjects (n=16), Cmax, AUC0-tau, and AUC0-inf of cyclobenzaprine increased in an approximately dose-proportional manner.
0-infIn a multiple-dose study of 5.6 mg of TONMYA administered sublingually once daily for 20 days in healthy subjects (n=26), approximately 2.5-fold accumulation of plasma cyclobenzaprine exposure was observed at steady-state.
The median time to peak plasma cyclobenzaprine concentration (Tmax) was approximately 4.3 hours for the 2.8 mg and 5.6 mg once daily TONMYA dosages.
Food Effect: A food effect study was conducted in healthy adult subjects (n=16) with a single sublingual 5.6 mg TONMYA dose. When TONMYA was administered with food, there was approximately 10% decrease in peak plasma concentration (Cmax) compared to the fasted state with no effect on exposure (AUC0-tau and AUC0-inf). These changes are not clinically significant.
TONMYA has a single dose elimination half-life of approximately 36 hours (range 28-59 hours; n=16).
Metabolism: Cyclobenzaprine is extensively metabolized. Cytochromes P-450 3A4, 1A2, and, to a lesser extent, 2D6 mediate N-demethylation, one of the oxidative pathways for cyclobenzaprine metabolism.
Excretion: Cyclobenzaprine is excreted primarily as glucuronides via the kidney.
Geriatric Patients: After cyclobenzaprine extended-release capsules dosing, the plasma cyclobenzaprine AUC was increased by 40% and the half-life of cyclobenzaprine was prolonged in geriatric subjects greater than 65 years of age compared to younger adult subjects 18 to 45 years of age (50 hours vs. 32 hours, respectively) [see Use in Specific Populations (8.5)]. There were no notable differences in Cmax or Tmax in this study.
Hepatic Impairment: In a pharmacokinetic study of immediate-release cyclobenzaprine tablets in 15 patients with mild hepatic impairment (HI) (Child-Pugh A) and 1 patient with moderate HI (Child-Pugh B), both AUC and Cmax were approximately double the values seen in subjects with normal hepatic function. The pharmacokinetics of cyclobenzaprine in patients with moderate HI (1 patient only) and severe HI is not known [see Use in Specific Populations (8.6)].
Advise the patient to read the FDA-approved patient labeling (Patient Information).
