CYCLOBENZAPRINE Drug Interactions: What You Need to Know

Drug Interactions Cyclobenzaprine may have life-threatening interactions with MAO inhibitors (see CONTRAINDICATIONS ). Postmarketing cases of serotonin syndrome have been reported during combined use of cyclobenzaprine hydrochloride and other drugs, such as SSRIs, SNRIs, TCAs, tramadol, bupropion, meperidine, verapamil, or MAO inhibitors. If concomitant treatment with cyclobenzaprine hydrochloride and other serotonergic drugs is clinically warranted, careful observation is advised, particularly during treatment initiation or dose increases (see WARNINGS ). Cyclobenzaprine may enhance the effects of alcohol, barbiturates, and other CNS depressants. Tricyclic antidepressants may block the antihypertensive action of guanethidine and similarly acting compounds. Tricyclic antidepressants may enhance the seizure risk in patients taking tramadol. Carcinogenesis, mutagenesis, impairment of fertility In rats treated with cyclobenzaprine hydrochloride for up to 67 weeks at doses of approximately 5 to 40 times the maximum recommended human dose, pale, sometimes enlarged, livers were noted and there was a dose-related hepatocyte vacuolation with lipidosis. In the higher dose groups this microscopic change was seen after 26 weeks and even earlier in rats which died prior to 26 weeks; at lower doses, the change was not seen until after 26 weeks. Cyclobenzaprine did not affect the onset, incidence or distribution of neoplasia in an 81-week study in the mouse or in a 105-week study in the rat. At oral doses of up to 10 times the human dose, cyclobenzaprine did not adversely affect the reproductive performance or fertility of male or female rats. Cyclobenzaprine did not demonstrate mutagenic activity in the male mouse at dose levels of up to 20 times the human dose.

Pregnancy Teratogenic

Effects.

Pregnancy

Category B Reproduction studies have been performed in rats, mice and rabbits at doses up to 20 times the human dose, and have revealed no evidence of impaired fertility or harm to the fetus due to cyclobenzaprine. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Nursing

Mothers It is not known whether this drug is excreted in human milk. Because cyclobenzaprine is closely related to the tricyclic antidepressants, some of which are known to be excreted in human milk, caution should be exercised when cyclobenzaprine hydrochloride is administered to a nursing woman.

Pediatric Use

Safety and effectiveness of cyclobenzaprine in pediatric patients below 15 years of age have not been established. Use in the Elderly The plasma concentration of cyclobenzaprine is increased in the elderly (see CLINICAL PHARMACOLOGY: Pharmacokinetics: Elderly .) The elderly may also be more at risk for CNS adverse events such as hallucinations and confusion, cardiac events resulting in falls or other sequelae, drug-drug and drug-disease interactions. For these reasons, in the elderly, cyclobenzaprine should be used only if clearly needed. In such patients cyclobenzaprine hydrochloride should be initiated with a 5 mg dose and titrated slowly upward.

Hypersensitivity to cyclobenzaprine or any inactive ingredient in TONMYA. Hypersensitivity reactions may manifest as an anaphylactic reaction, urticaria, facial and/or tongue swelling, or pruritus. Discontinue TONMYA if a hypersensitivity reaction is suspected. Concomitant use of monoamine oxidase (MAO) inhibitors or within 14 days after discontinuation of a MAO inhibitor. Hyperpyretic crisis seizures and deaths have occurred in patients who received cyclobenzaprine (or structurally similar tricyclic antidepressants) concomitantly with MAO inhibitors drugs. During the acute recovery phase of myocardial infarction, and in patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure. Hyperthyroidism. Hypersensitivity to cyclobenzaprine or any inactive ingredient in TONMYA ( 4 ) Concomitant use of monoamine oxidase (MAO) inhibitors or within 14 days after their discontinuation ( 4 ) During acute recovery phase of myocardial infarction and in patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure ( 4 ) Hyperthyroidism ( 4 )

AND PRECAUTIONS Embryofetal Toxicity : Based on animal data, TONMYA may cause neural tube defects when used two weeks prior to conception and through the first trimester of pregnancy. Advise females of reproductive potential of the potential risk and to use effective contraception during treatment and for two weeks after the final dose. ( 5.1 , 8.1 , 8.3 )

Serotonin

Syndrome: Potentially life-threatening serotonin syndrome has been reported with cyclobenzaprine when used in combination with other drugs. Immediately discontinue concomitant treatment with TONMYA and a serotonergic agent if serotonin syndrome symptoms occur and initiate supportive symptomatic treatment. If concomitant treatment with TONMYA and other serotonergic drugs is clinically warranted, careful observation is advised, particularly during treatment initiation or dosage increases. ( 5.2 )

Tricyclic

Antidepressant-like Adverse Reactions: TCAs have been reported to produce arrhythmias, sinus tachycardia, prolongation of the conduction time leading to myocardial infarction and stroke. TCAs lower the seizure threshold, and are associated with serious CNS reactions. If clinically significant CNS symptoms develop, consider discontinuation of TONMYA. ( 5.3 ) Atropine-like Adverse Reactions: Use with caution in patients with a history of urinary retention, angle-closure glaucoma, increased intraocular pressure and in patients taking anticholinergic medications. ( 5.4 )

Cns

Depression and Risk of Operating a Motor Vehicle or Hazardous Machinery: TONMYA monotherapy may cause CNS depression. Advise patients not to operate a motor vehicle or other dangerous machinery until they are reasonably certain that TONMYA therapy will not adversely affect their ability to engage in such activities. ( 5.5 )

Oral Mucosal Adverse

Reactions : In clinical studies, oral mucosal adverse reactions occurred more frequently in TONMYA-treated patients compared to placebo-treated patients. Advise patients to moisten the mouth with sips of water before administration of TONMYA to reduce the risk of oral sensory changes (hypoesthesia). Consider discontinuation of TONMYA if severe reactions occur. ( 5.6 )

5.1 Embryofetal Toxicity 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 <span class="opacity-50 text-xs">[see Use in Specific Populations (8.1 , 8.3) ]</span>.

5.2 Serotonin Syndrome 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 <span class="opacity-50 text-xs">[see Contraindications (4) ]</span> . 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.

5.3 Tricyclic Antidepressant-like Adverse Reactions 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 <span class="opacity-50 text-xs">[see Contraindications (4) ]</span> . 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.

5.4 Atropine-like Adverse Reactions 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.

5.5 CNS Depression and Risk of Operating a Motor Vehicle or Hazardous Machinery 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 <span class="opacity-50 text-xs">[see Drug Interactions (7) ]</span>. 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.

5.6 Oral Mucosal Adverse Reactions 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%) <span class="opacity-50 text-xs">[see Adverse Reactions (6.1) ]</span>. 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.