Umeclidinium Bromide and Vilanterol Trifenatate

Umeclidinium and Vilanterol ELLIPTA is indicated for the maintenance treatment of patients with chronic obstructive pulmonary disease (COPD). Limitations of Use Umeclidinium and Vilanterol ELLIPTA is NOT indicated for the relief of acute bronchospasm or for the treatment of asthma. The safety and effectiveness of Umeclidinium and Vilanterol ELLIPTA in asthma have not been established. Umeclidinium and Vilanterol ELLIPTA is a combination of umeclidinium, an anticholinergic, and vilanterol, a long-acting beta 2 -adrenergic agonist (LABA), indicated for the maintenance treatment of patients with chronic obstructive pulmonary disease (COPD). ( 1 ) Limitations of Use: Not indicated for relief of acute bronchospasm or for the treatment of asthma. ( 1 , 5.2 )

Inhalation powder: 62.5 mcg umeclidinium and 25 mcg vilanterol (62.5/25 mcg) per actuation. Inhalation powder: 62.5 mcg umeclidinium and 25 mcg vilanterol (62.5/25 mcg) per actuation. ( 3 )

Umeclidinium and Vilanterol ELLIPTA is contraindicated in:

• patients with severe hypersensitivity to milk proteins or who have demonstrated hypersensitivity to umeclidinium, vilanterol, or any of the excipients [see Warnings and Precautions ( 5.6 ), Description ( 11 )] .
• use of a long-acting beta 2 -adrenergic agonist (LABA), including vilanterol, one of the active ingredients in Umeclidinium and Vilanterol ELLIPTA, without an inhaled corticosteroid (ICS), in patients with asthma [see Warnings and Precautions ( 5.1 )] . Umeclidinium and Vilanterol ELLIPTA is not indicated for the treatment of asthma.
• Severe hypersensitivity to milk proteins or any ingredients. ( 4 )
• Use of a LABA, including Umeclidinium and Vilanterol ELLIPTA, without an inhaled corticosteroid is contraindicated in patients with asthma. ( 4 )

• LABA monotherapy (without an inhaled corticosteroid) for asthma increases the risk of serious asthma-related events. ( 5.1 )
• Do not initiate in acutely deteriorating COPD. Do not use to treat acute symptoms. ( 5.2 )
• Do not use in combination with additional therapy containing a LABA because of risk of overdose. ( 5.3 )
• If paradoxical bronchospasm occurs, discontinue Umeclidinium and Vilanterol ELLIPTA and institute alternative therapy. ( 5.5 )
• Use with caution in patients with cardiovascular disorders because of beta-adrenergic stimulation. ( 5.7 )
• Use with caution in patients with convulsive disorders, thyrotoxicosis, diabetes mellitus, and ketoacidosis. ( 5.8 )
• Worsening of narrow-angle glaucoma may occur. Use with caution in patients with narrow-angle glaucoma and instruct patients to contact a healthcare provider immediately if symptoms occur. ( 5.9 )
• Worsening of urinary retention may occur. Use with caution in patients with prostatic hyperplasia or bladder-neck obstruction and instruct patients to contact a healthcare provider immediately if symptoms occur. ( 5.10 )
• Be alert to hypokalemia and hyperglycemia. ( 5.11 )

5.1 Serious Asthma-Related Events – Hospitalizations, Intubations, Death The safety and effectiveness of Umeclidinium and Vilanterol ELLIPTA in patients with asthma have not been established. Umeclidinium and Vilanterol ELLIPTA is not indicated for the treatment of asthma [see Contraindications ( 4 )] . Use of LABA as monotherapy (without ICS) for asthma is associated with an increased risk of asthma-related death. Available data from controlled clinical trials also suggest that use of LABA as monotherapy increases the risk of asthma-related hospitalization in pediatric and adolescent patients. These findings are considered a class effect of LABA monotherapy. When LABA are used in fixed-dose combination with ICS, data from large clinical trials do not show a significant increase in the risk of serious asthma-related events (hospitalizations, intubations, death) compared with ICS alone. Salmeterol Multicenter Asthma Research Trial (SMART) A 28-week, placebo-controlled, U.S. trial that compared the safety of another LABA (salmeterol) with placebo, each added to usual asthma therapy, showed an increase in asthma‑related deaths in subjects receiving salmeterol (13/13,176 in subjects treated with salmeterol vs. 3/13,179 in subjects treated with placebo; relative risk: 4.37 [95% CI: 1.25, 15.34]). The increased risk of asthma-related death is considered a class effect of LABAs, including vilanterol, one of the active ingredients in Umeclidinium and Vilanterol ELLIPTA. No trial adequate to determine whether the rate of asthma-related death is increased in subjects treated with Umeclidinium and Vilanterol ELLIPTA has been conducted. Available data do not suggest an increased risk of death with use of LABA in patients with COPD.

5.2 Deterioration of Disease and Acute Episodes Umeclidinium and Vilanterol ELLIPTA should not be initiated in patients during rapidly deteriorating or potentially life-threatening episodes of COPD. Umeclidinium and Vilanterol ELLIPTA has not been studied in subjects with acutely deteriorating COPD. The initiation of Umeclidinium and Vilanterol ELLIPTA in this setting is not appropriate. If Umeclidinium and Vilanterol ELLIPTA no longer controls symptoms of bronchoconstriction; the patient’s inhaled, short-acting beta 2 -agonist becomes less effective; or the patient needs more short-acting beta 2 ‑agonist than usual, these may be markers of deterioration of disease. In this setting, re‑evaluate the patient and the COPD treatment regimen at once. The daily dose of Umeclidinium and Vilanterol ELLIPTA should not be increased. Increasing use of inhaled, short-acting beta 2 -agonists is a signal of deteriorating disease. In this situation, the patient requires immediate re-evaluation with reassessment of the treatment regimen, giving special consideration to the need for additional therapeutic options. Patients should not use more than 1 inhalation of Umeclidinium and Vilanterol ELLIPTA once daily. Umeclidinium and Vilanterol ELLIPTA should not be used for the relief of acute symptoms, i.e., as rescue therapy for the treatment of acute episodes of bronchospasm. Umeclidinium and Vilanterol ELLIPTA has not been studied in the relief of acute symptoms and extra doses should not be used for that purpose. Acute symptoms should be treated with an inhaled, short-acting beta 2 -agonist. When beginning treatment with Umeclidinium and Vilanterol ELLIPTA, patients who have been taking oral or inhaled, short-acting beta 2 -agonists on a regular basis (e.g., 4 times a day) should be instructed to discontinue the regular use of these drugs and to use them only for symptomatic relief of acute respiratory symptoms. When prescribing Umeclidinium and Vilanterol ELLIPTA, the healthcare provider should also prescribe an inhaled, short-acting beta 2 -agonist and instruct the patient on how it should be used.

5.3 Avoid Excessive Use of Umeclidinium and Vilanterol ELLIPTA and Avoid Use with Other Long-Acting Beta 2 -Agonists Umeclidinium and Vilanterol ELLIPTA should not be used more often than recommended, at higher doses than recommended, or in conjunction with other therapies containing LABAs, as an overdose may result. Clinically significant cardiovascular effects and fatalities have been reported in association with excessive use of inhaled sympathomimetic drugs. Patients using Umeclidinium and Vilanterol ELLIPTA should not use another therapy containing a LABA (e.g., salmeterol, formoterol fumarate, arformoterol tartrate, indacaterol) for any reason.

5.4 Drug Interactions with Strong Cytochrome P450 3A4 Inhibitors Caution should be exercised when considering the coadministration of Umeclidinium and Vilanterol ELLIPTA with ketoconazole and other known strong cytochrome P450 3A4 (CYP3A4) inhibitors (including, but not limited to, ritonavir, clarithromycin, conivaptan, indinavir, itraconazole, lopinavir, nefazodone, nelfinavir, saquinavir, telithromycin, troleandomycin, voriconazole) because increased cardiovascular adverse effects may occur [see Drug Interactions ( 7.1 ), Clinical Pharmacology ( 12.3 )] .

5.5 Paradoxical Bronchospasm As with other inhaled therapies, Umeclidinium and Vilanterol ELLIPTA can produce paradoxical bronchospasm, which may be life threatening. If paradoxical bronchospasm occurs following dosing with Umeclidinium and Vilanterol ELLIPTA, it should be treated immediately with an inhaled, short-acting bronchodilator; Umeclidinium and Vilanterol ELLIPTA should be discontinued immediately; and alternative therapy should be instituted.

5.6 Hypersensitivity Reactions, including Anaphylaxis Hypersensitivity reactions such as anaphylaxis, angioedema, rash, and urticaria may occur after administration of Umeclidinium and Vilanterol ELLIPTA. Discontinue Umeclidinium and Vilanterol ELLIPTA if such reactions occur. There have been reports of anaphylactic reactions in patients with severe milk protein allergy after inhalation of other powder medications containing lactose; therefore, patients with severe milk protein allergy should not use Umeclidinium and Vilanterol ELLIPTA [see Contraindications ( 4 ), Adverse Reactions ( 6.2 )] .

5.7 Cardiovascular Effects Vilanterol, like other beta 2 -agonists, can produce a clinically significant cardiovascular effect in some patients as measured by increases in pulse rate, systolic or diastolic blood pressure, and also cardiac arrhythmias, such as supraventricular tachycardia and extrasystoles. If such effects occur, Umeclidinium and Vilanterol ELLIPTA may need to be discontinued. In addition, beta-agonists have been reported to produce electrocardiographic changes, such as flattening of the T wave, prolongation of the QTc interval, and ST segment depression, although the clinical significance of these findings is unknown [see Clinical Pharmacology ( 12.2 )] . […]

The following clinically significant adverse reactions are described elsewhere in labeling:

• Serious asthma-related events–hospitalizations, intubations, death [see Warnings and Precautions ( 5.1 )]
• Paradoxical bronchospasm [see Warnings and Precautions ( 5.5 )]
• Cardiovascular effects [see Warnings and Precautions ( 5.7 )]
• Worsening of narrow-angle glaucoma [see Warnings and Precautions ( 5.9 )]
• Worsening of urinary retention [see Warnings and Precautions ( 5.10 )] Most common adverse reactions (incidence ≥1% and more common than placebo) are pharyngitis, sinusitis, lower respiratory tract infection, constipation, diarrhea, pain in extremity, muscle spasms, neck pain, and chest pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Prasco Laboratories at 1-866-525-0688 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice. The clinical program for umeclidinium and vilanterol ELLIPTA included 8,138 subjects with COPD in four 6‑month lung function trials, one 12-month long-term safety study, and 9 other trials of shorter duration. A total of 1,124 subjects have received at least 1 dose of umeclidinium and vilanterol ELLIPTA (umeclidinium/vilanterol 62.5/25 mcg), and 1,330 subjects have received a higher dose of umeclidinium/vilanterol (125/25 mcg). The safety data described below are based on the four 6-month and one 12-month trials. Adverse reactions observed in the other trials were similar to those observed in the confirmatory trials. 6-Month Trials The incidence of adverse reactions associated with umeclidinium and vilanterol ELLIPTA in Table 1 is based on four 6-month trials: 2 placebo-controlled trials (Trial 1 and Trial 2); N = 1,532 and N = 1,489, respectively) and 2 active-controlled trials (Trial 3 and Trial 4); N = 843 and N = 869, respectively). Of the 4,733 subjects, 68% were male and 84% were white. They had a mean age of 63 years and an average smoking history of 45 pack-years, with 50% identified as current smokers. At screening, the mean postbronchodilator percent predicted forced expiratory volume in 1 second (FEV 1 ) was 48% (range: 13% to 76%), the mean postbronchodilator FEV 1 /forced vital capacity (FVC) ratio was 0.47 (range: 0.13 to 0.78), and the mean percent reversibility was 14% (range: -45% to 109%). Subjects received 1 dose once daily of the following: umeclidinium and vilanterol ELLIPTA, umeclidinium/vilanterol 125/25 mcg, umeclidinium 62.5 mcg, umeclidinium 125 mcg, vilanterol 25 mcg, active control, or placebo. Table 1. Adverse Reactions with Umeclidinium and Vilanterol ELLIPTA with ≥1% Incidence and More Common than Placebo in Subjects with Chronic Obstructive Pulmonary Disease Adverse Reaction Umeclidinium and Vilanterol ELLIPTA (n = 842) % Umeclidinium 62.5 mcg (n = 418) % Vilanterol 25 mcg (n = 1,034) % Placebo (n = 555) % Infections and infestations Pharyngitis 2 1 2 <1 Sinusitis 1 <1 1 <1 Lower respiratory tract infection 1 <1 <1 <1 Gastrointestinal disorders Constipation 1 <1 <1 <1 Diarrhea 2 <1 2 1 Musculoskeletal and connective tissue disorders Pain in extremity 2 <1 2 1 Muscle spasms 1 <1 <1 <1 Neck pain 1 <1 <1 <1 General disorders and administration site conditions Chest pain 1 <1 <1 <1 Other adverse reactions with umeclidinium and vilanterol ELLIPTA observed with an incidence <1% but more common than placebo included the following: productive cough, dry mouth, dyspepsia, abdominal pain, gastroesophageal reflux disease, vomiting, musculoskeletal chest pain, chest discomfort, asthenia, atrial fibrillation, ventricular extrasystoles, supraventricular extrasystoles, myocardial infarction, pruritus, rash, and conjunctivitis. 12-Month Trial In a long-term safety trial (Trial 5), 335 subjects were treated for up to 12 months with umeclidinium/vilanterol 125/25 mcg or placebo. The demographic and baseline characteristics of the long-term safety trial were similar to those of the placebo‑controlled efficacy trials described above. Adverse reactions observed with a frequency of ≥1% in the group receiving umeclidinium/vilanterol 125/25 mcg that exceeded that in placebo in this trial were: headache, back pain, sinusitis, cough, urinary tract infection, arthralgia, nausea, vertigo, abdominal pain, pleuritic pain, viral respiratory tract infection, toothache, and diabetes mellitus.

6.2 Postmarketing Experience In addition to adverse reactions reported from clinical trials, the following adverse reactions have been identified during postapproval use of umeclidinium and vilanterol ELLIPTA. Because 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. These events have been chosen for inclusion due to either their seriousness, frequency of reporting, or causal connection to umeclidinium and vilanterol ELLIPTA or a combination of these factors. Cardiac Disorders Palpitations. Eye Disorders Blurred vision, eye pain, glaucoma, increased intraocular pressure. Immune System Disorders Hypersensitivity reactions, including anaphylaxis, angioedema, and urticaria. Nervous System Disorders Dysgeusia, tremor. Psychiatric Disorders Anxiety. Renal and Urinary Disorders Dysuria, urinary retention. Respiratory, Thoracic, and Mediastinal Disorders Dysphonia, paradoxical bronchospasm.

• Strong cytochrome P450 3A4 inhibitors (e.g., ketoconazole): Use with caution. May cause cardiovascular effects. ( 7.1 )
• Monoamine oxidase inhibitors and tricyclic antidepressants: Use with extreme caution. May potentiate effect of vilanterol on cardiovascular system. ( 7.2 )
• Beta-blockers: Use with caution. May block bronchodilatory effects of beta-agonists and produce severe bronchospasm. ( 7.3 )
• Diuretics: Use with caution. Electrocardiographic changes and/or hypokalemia associated with non–potassium-sparing diuretics may worsen with concomitant beta-agonists. ( 7.4 )
• Anticholinergics: May interact additively with concomitantly used anticholinergic medications. Avoid administration of Umeclidinium and Vilanterol ELLIPTA with other anticholinergic-containing drugs. ( 7.5 )

7.1 Inhibitors of Cytochrome P450 3A4 Vilanterol is a substrate of CYP3A4. Concomitant administration of the strong CYP3A4 inhibitor ketoconazole increases the systemic exposure to vilanterol. Caution should be exercised when considering the coadministration of Umeclidinium and Vilanterol ELLIPTA with ketoconazole and other known strong CYP3A4 inhibitors [see Warnings and Precautions ( 5.4 ), Clinical Pharmacology ( 12.3 )] .

7.2 Monoamine Oxidase Inhibitors, Tricyclic Antidepressants, and QTc Prolonging Drugs Vilanterol, like other beta 2 -agonists, should be administered with extreme caution to patients being treated with monoamine oxidase inhibitors, tricyclic antidepressants, or drugs known to prolong the QTc interval or within 2 weeks of discontinuation of such agents, because the effect of adrenergic agonists on the cardiovascular system may be potentiated by these agents. Drugs that are known to prolong the QTc interval have an increased risk of ventricular arrhythmias.

7.3 Beta-Adrenergic Receptor Blocking Agents Beta-blockers not only block the pulmonary effect of beta-agonists, such as vilanterol, but may also produce severe bronchospasm in patients with COPD. Therefore, patients with COPD should not normally be treated with beta-blockers. However, under certain circumstances, there may be no acceptable alternatives to the use of beta‑adrenergic blocking agents for these patients; cardioselective beta-blockers could be considered, although they should be administered with caution.

7.4 Non–Potassium-Sparing Diuretics The electrocardiographic changes and/or hypokalemia that may result from the administration of non–potassium-sparing diuretics (such as loop or thiazide diuretics) can be acutely worsened by beta-agonists, especially when the recommended dose of the beta-agonist is exceeded. Although the clinical significance of these effects is not known, caution is advised in the coadministration of beta-agonists with non–potassium-sparing diuretics.

7.5 Anticholinergics There is potential for an additive interaction with concomitantly used anticholinergic medicines. Therefore, avoid coadministration of Umeclidinium and Vilanterol ELLIPTA with other anticholinergic-containing drugs as this may lead to an increase in anticholinergic adverse effects [see Warnings and Precautions ( 5.9 , 5.10 )] .

8.1 Pregnancy Risk Summary There are insufficient data on the use of umeclidinium and vilanterol ELLIPTA or its individual components, umeclidinium and vilanterol, in pregnant women to inform a drug-associated risk. (See Clinical Considerations.) In animal reproduction studies, umeclidinium administered via inhalation or subcutaneously to pregnant rats and rabbits was not associated with adverse effects on embryofetal development at exposures approximately 50 and 200 times, respectively, the human exposure at the maximum recommended human daily inhaled dose (MRHDID). Vilanterol administered via inhalation to pregnant rats and rabbits produced no fetal structural abnormalities at exposures approximately 70 times the MRHDID. (See Data.) The estimated risk of major birth defects and miscarriage for the indicated populations is unknown. In the U.S. general population, the estimated risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Labor or Delivery: Umeclidinium and Vilanterol ELLIPTA should be used during late gestation and labor only if the potential benefit justifies the potential for risks related to beta-agonists interfering with uterine contractility. Data Animal Data: The combination of umeclidinium and vilanterol has not been studied in pregnant animals. Studies in pregnant animals have been conducted with umeclidinium and vilanterol individually. Umeclidinium: In separate embryofetal developmental studies, pregnant rats and rabbits received umeclidinium during the period of organogenesis at doses up to approximately 50 and 200 times the MRHDID, respectively (on an AUC basis at maternal inhalation doses up to 278 mcg/kg/day in rats and at maternal subcutaneous doses up to 180 mcg/kg/day in rabbits). No evidence of teratogenic effects was observed in either species. In a perinatal and postnatal developmental study in rats, dams received umeclidinium during late gestation and lactation periods with no evidence of effects on offspring development at doses up to approximately 26 times the MRHDID (on an AUC basis at maternal subcutaneous doses up to 60 mcg/kg/day). Vilanterol: In separate embryofetal developmental studies, pregnant rats and rabbits received vilanterol during the period of organogenesis at doses up to approximately 13,000 and 450 times, respectively, the MRHDID (on a mcg/m 2 basis at maternal inhalation doses up to 33,700 mcg/kg/day in rats and on an AUC basis at maternal inhaled doses up to 5,740 mcg/kg/day in rabbits). No evidence of structural abnormalities was observed at any dose in rats or in rabbits up to approximately 70 times the MRHDID (on an AUC basis at maternal doses up to 591 mcg/kg/day in rabbits). However, fetal skeletal variations were observed in rabbits at approximately 450 times the MRHDID (on an AUC basis at maternal inhaled or subcutaneous doses of 5,740 or 300 mcg/kg/day, respectively). The skeletal variations included decreased or absent ossification in cervical vertebral centrum and metacarpals. In a perinatal and postnatal developmental study in rats, dams received vilanterol during late gestation and the lactation periods at doses up to approximately 3,900 times the MRHDID (on a mcg/m 2 basis at maternal oral doses up to 10,000 mcg/kg/day). No evidence of effects in offspring development was observed.

8.2 Lactation Risk Summary There is no information available on the presence of umeclidinium or vilanterol in human milk, the effects on the breastfed child, or the effects on milk production. Umeclidinium was detected in the plasma of offspring of lactating rats treated with umeclidinium suggesting its presence in maternal milk. (See Data.) The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Umeclidinium and Vilanterol ELLIPTA and any potential adverse effects on the breastfed child from umeclidinium or vilanterol or from the underlying maternal condition. Data Subcutaneous administration of umeclidinium to lactating rats at greater than or equal to 60 mcg/kg/day resulted in a quantifiable level of umeclidinium in 2 of 54 pups, which may indicate transfer of umeclidinium in rat milk.

8.4 Pediatric Use The safety and effectiveness of Umeclidinium and Vilanterol ELLIPTA have not been established in pediatric patients. Umeclidinium and Vilanterol ELLIPTA is not indicated for use in pediatric patients.

8.5 Geriatric Use Based on available data, no adjustment of the dosage of Umeclidinium and Vilanterol ELLIPTA in geriatric patients is necessary, but greater sensitivity in some older individuals cannot be ruled out. Clinical trials of umeclidinium and vilanterol ELLIPTA for COPD included 2,143 subjects aged 65 years and older and 478 subjects aged 75 years and older. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger subjects.

8.6 Hepatic Impairment Patients with moderate hepatic impairment (Child-Pugh score of 7-9) showed no relevant increases in C max or AUC, nor did protein binding differ between subjects with moderate hepatic impairment and their healthy controls. Studies in subjects with severe hepatic impairment have not been performed [see Clinical Pharmacology ( 12.3 )] .

8.7 Renal Impairment There were no significant increases in either umeclidinium or vilanterol exposure in subjects with severe renal impairment (CrCl <30 mL/min) compared with healthy subjects. No dosage adjustment is required in patients with renal impairment [see Clinical Pharmacology ( 12.3 )] .

Umeclidinium and Vilanterol ELLIPTA Umeclidinium and Vilanterol ELLIPTA contains both umeclidinium and vilanterol. The mechanisms of action described below for the individual components apply to Umeclidinium and Vilanterol ELLIPTA. These drugs represent 2 different classes of medications (an anticholinergic and a LABA) each having different effects on clinical and physiological indices. Umeclidinium Umeclidinium is a long-acting muscarinic antagonist, which is often referred to as an anticholinergic. It has similar affinity to the subtypes of muscarinic receptors M1 to M5. In the airways, it exhibits pharmacological effects through inhibition of M3 receptor at the smooth muscle leading to bronchodilation. The competitive and reversible nature of antagonism was shown with human and animal origin receptors and isolated organ preparations. In preclinical in vitro as well as in vivo studies, prevention of methacholine- and acetylcholine-induced bronchoconstrictive effects was dose-dependent and lasted longer than 24 hours. The clinical relevance of these findings is unknown. The bronchodilation following inhalation of umeclidinium is predominantly a site-specific effect. Vilanterol Vilanterol is a LABA. In vitro tests have shown the functional selectivity of vilanterol was similar to salmeterol. The clinical relevance of this in vitro finding is unknown. Although beta 2 -receptors are the predominant adrenergic receptors in bronchial smooth muscle and beta 1 -receptors are the predominant receptors in the heart, there are also beta 2 -receptors in the human heart comprising 10% to 50% of the total beta-adrenergic receptors. The precise function of these receptors has not been established, but they raise the possibility that even highly selective beta 2 -agonists may have cardiac effects. The pharmacologic effects of beta 2 -adrenergic agonist drugs, including vilanterol, are at least in part attributable to stimulation of intracellular adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3′,5′-adenosine monophosphate (cyclic AMP). Increased cyclic AMP levels cause relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from cells, especially from mast cells.