Drug Monograph
Asmanex (Mometasone Furoate Inhaled)
mometasone furoate inhalation powder / inhalation aerosol
Pharmacokinetic Profile
Half-Life
~4.5 h (IV); ~5 h (effective)
Metabolism
Hepatic via CYP3A4
Protein Binding
98–99%
Bioavailability
<1% (DPI); ~11% (absolute, inhaled)
Volume of Distribution
~499 L (IV)
Clinical Information
Drug Class
Inhaled Corticosteroid
Available Doses
DPI: 110, 220 mcg; HFA: 50, 100, 200 mcg/actuation
Route
Oral inhalation
Renal Adjustment
Not required
Hepatic Adjustment
Monitor; increased systemic exposure possible in severe impairment
Pregnancy
Use only if benefit justifies risk (animal teratogenicity)
Lactation
No human data; weigh benefits vs risks
Schedule / Legal Status
Rx only (not a controlled substance)
Generic Available
No (brand only as of 2026)
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Persistent asthma — maintenance prophylaxis (Twisthaler DPI) | ≥4 years | Monotherapy or adjunctive | FDA Approved |
| Persistent asthma — maintenance prophylaxis (HFA MDI) | ≥5 years | Monotherapy or adjunctive | FDA Approved |
Mometasone furoate inhaled is approved exclusively for the maintenance treatment of asthma as prophylactic therapy. It is not a rescue medication and must not be used to treat acute bronchospasm or status asthmaticus. Both formulations — the Twisthaler dry powder inhaler and the HFA metered-dose inhaler — serve as step 2–4 controller therapy in national and international asthma guidelines (GINA, NAEPP). The GINA guidelines position medium-potency inhaled corticosteroids like mometasone as foundational controller therapy across all asthma severity steps above intermittent disease.
Off-Label Uses
Eosinophilic bronchitis without asthma: ICS therapy, including mometasone, is recommended by the ACCP cough guidelines for chronic cough with sputum eosinophilia. Evidence quality: Moderate.
Exercise-induced bronchoconstriction prophylaxis (daily controller): Daily ICS use reduces the severity and frequency of exercise-triggered symptoms when used as maintenance, per ATS guidelines. Evidence quality: Moderate.
Dosing
Asmanex Twisthaler (DPI) — Adults & Adolescents
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Mild persistent asthma — previously on bronchodilators only (≥12 y) | 220 mcg once daily (evening) | 220 mcg once daily | 440 mcg/day | Evening dosing preferred for once-daily use Onset of benefit: 1–2 weeks |
| Moderate persistent asthma — previously on inhaled corticosteroids (≥12 y) | 220 mcg once daily (evening) | 220–440 mcg/day | 440 mcg/day | 440 mcg may be given as 220 mcg BID or 440 mcg once daily Titrate to lowest effective dose once stable |
| Severe asthma — transitioning from oral corticosteroids (≥12 y) | 440 mcg twice daily | 440 mcg BID | 880 mcg/day | Reduce prednisone by 2.5 mg/week after ≥1 week of mometasone Monitor for adrenal insufficiency during taper |
| Pediatric asthma (4–11 y) | 110 mcg once daily (evening) | 110 mcg once daily | 110 mcg/day | Same dose regardless of prior therapy Use 110 mcg Twisthaler device |
Asmanex HFA (MDI) — All Populations
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Mild-to-moderate persistent asthma (≥12 y) — previously on bronchodilators or low-dose ICS | 2 inhalations of 100 mcg BID | 200 mcg BID (400 mcg/day) | 800 mcg/day | Starting strength based on prior therapy Prime with 4 sprays before first use; re-prime if unused >5 days |
| Moderate-to-severe persistent asthma (≥12 y) — previously on medium/high-dose ICS | 2 inhalations of 200 mcg BID | 400 mcg BID (800 mcg/day) | 800 mcg/day | Titrate down after stability achieved Rinse mouth after each use |
| Pediatric asthma (5–11 y) | 2 inhalations of 50 mcg BID | 100 mcg BID (200 mcg/day) | 200 mcg/day | Only the 50 mcg per actuation strength is approved for this age group |
Clinical Pearl: Once-Daily Evening Dosing
For the Twisthaler, once-daily dosing should be administered in the evening. Clinical trials demonstrated that evening administration provides comparable FEV1 improvement to twice-daily dosing in patients with mild-to-moderate disease (FDA PI). Once-daily dosing improves adherence, which is the single largest driver of ICS efficacy in real-world practice. If response is inadequate after 2 weeks of once-daily therapy, consider stepping up to twice-daily dosing before switching agents.
Pharmacology
Mechanism of Action
Mometasone furoate is a potent synthetic corticosteroid that exerts its therapeutic effect primarily through local anti-inflammatory activity in the airways. After binding to intracellular glucocorticoid receptors, the drug-receptor complex translocates to the nucleus where it modulates gene transcription. This results in broad suppression of inflammatory mediators including cytokines, leukotrienes, and prostaglandins, while simultaneously reducing recruitment and activation of eosinophils, mast cells, macrophages, and lymphocytes. Mometasone demonstrates exceptionally high glucocorticoid receptor affinity — approximately 12 times that of dexamethasone, 7 times triamcinolone acetonide, 5 times budesonide, and 1.5 times fluticasone propionate. This potent receptor binding, combined with high lipophilicity and tissue retention in the airways, underlies its clinical effectiveness at relatively low delivered doses.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Systemic bioavailability <1% (DPI, per FDA methodology); ~11% absolute bioavailability (independent studies); oral bioavailability negligible due to extensive first-pass | Swallowed portion is almost entirely cleared by first-pass metabolism, minimizing systemic exposure; the primary systemic absorption is from the lung |
| Distribution | Vd ~499 L (IV); protein binding 98–99% | Extensive tissue distribution and high protein binding limit free drug in circulation, contributing to the favorable topical-to-systemic ratio |
| Metabolism | Hepatic via CYP3A4 to multiple metabolites; no major active metabolites detected in plasma; minor metabolite: 6β-hydroxy-mometasone furoate | Strong CYP3A4 inhibitors (ketoconazole, ritonavir) can increase systemic mometasone exposure; no active metabolites means parent drug drives all activity |
| Elimination | t½ ~4.5 h (IV); excreted as metabolites via bile (predominantly) and urine (minor) | Rapid clearance from plasma supports once- or twice-daily dosing; the clinical duration of airway effect extends beyond the plasma half-life due to tissue retention |
Side Effects
≥10%
Very Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Headache | 17–22% | Most frequently reported; similar incidence to placebo (20%) in controlled trials; usually mild and self-limiting |
| Allergic rhinitis | 11–15% | May reflect underlying atopy rather than a drug effect; consider intranasal corticosteroid co-therapy |
| Pharyngitis | 8–13% | Related to local deposition; mouth rinsing after inhalation reduces incidence |
| Upper respiratory tract infection | 8–15% | Reported at similar rates across ICS class; not clearly dose-related |
1–10%
Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Oral candidiasis | 4–6% | Dose-related; significantly reduced by mouth rinsing; treat with topical antifungal without necessarily discontinuing ICS |
| Sinusitis | 5–6% | Similar frequency to placebo in controlled trials |
| Dysmenorrhea | 4–9% | Reported in female patients; relationship to drug not established; higher rates observed at 220 mcg BID |
| Musculoskeletal pain | 4–8% | Includes myalgia and back pain; more frequent at higher doses |
| Back pain | 3–6% | Not clearly distinguishable from background rates |
| Dyspepsia | 3–5% | May be related to swallowed fraction; mouth rinsing and spitting may help |
| Dysphonia | 1–3% | Due to local laryngeal myopathy from steroid deposition; use spacer (HFA) or rinse; frequency increases with long-term use |
| Epistaxis | 1–3% | Uncommon with inhaled route; more common with nasal formulation |
Serious
Serious Adverse Effects (Regardless of Frequency)
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Adrenal suppression / HPA axis dysfunction | Rare at recommended doses | Weeks to months (chronic use; higher doses) | Gradual dose reduction; assess AM cortisol or ACTH stimulation test; supplemental systemic steroids during stress |
| Anaphylaxis / severe hypersensitivity (including milk protein allergy) | Very rare (postmarketing) | Minutes to hours after dose | Immediate emergency treatment; permanent discontinuation; Twisthaler is contraindicated in milk protein allergy (contains lactose with trace milk proteins) |
| Paradoxical bronchospasm | Rare | Immediately after inhalation | Treat with rescue bronchodilator; discontinue mometasone; switch to alternative ICS |
| Glaucoma / raised intraocular pressure | 0.3% (8/3007 patients in clinical trials) | Months to years of use | Ophthalmology referral; regular IOP monitoring in long-term users; consider ICS dose reduction |
| Posterior subcapsular cataracts | 0.9% in long-term trials | Months to years | Periodic ophthalmological examination recommended for long-term users |
| Reduced bone mineral density | Significant BMD decrease reported in 2-year trial (mean -1.43% lumbar spine at 220 mcg BID) | Years of continuous use | DEXA scan in patients with osteoporosis risk factors; calcium/vitamin D supplementation; use lowest effective dose |
| Growth suppression (pediatric) | Mean reduction ~1 cm/year (ICS class effect) | Within first year of treatment | Regular stadiometry; titrate to lowest effective dose; long-term impact on final adult height uncertain |
Discontinuation
Discontinuation Rates
Adults & Adolescents (≥12 y) — Short-Term Trials
~3–5% vs ~3% placebo
Top reasons: Asthma worsening, headache, oral candidiasis
Oral Steroid Transition Trial (Adults)
Higher rates expected due to steroid withdrawal
Top reasons: Asthma exacerbation during taper, fatigue, musculoskeletal symptoms
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Asthma worsening / exacerbation | ~2% | Most common reason in both treatment and placebo arms; more common during oral steroid taper |
| Oral candidiasis | <1% | Rarely leads to discontinuation when managed with topical antifungals |
| Headache | <1% | Usually transient and not distinguishable from placebo rates |
Managing Oral Candidiasis
Oropharyngeal thrush occurred in approximately 6.5% of patients in the clinical program (195 of 3007). The single most effective prevention strategy is mouth rinsing with water and spitting after every dose. When thrush develops, treat with oral nystatin suspension or clotrimazole troches without interrupting ICS therapy unless symptoms are refractory. Using a spacer device with the HFA formulation can further reduce oropharyngeal deposition.
Drug Interactions
Mometasone furoate is metabolized primarily by CYP3A4. Under normal conditions, systemic plasma levels after inhalation are very low, limiting the clinical significance of most pharmacokinetic interactions. However, concurrent use of potent CYP3A4 inhibitors can meaningfully increase systemic mometasone exposure and the associated risk of corticosteroid-related adverse effects.
Major
Ketoconazole
MechanismPotent CYP3A4 inhibition reducing mometasone hepatic clearance
EffectIncreased mometasone plasma concentrations; 4 of 12 healthy subjects had peak levels >200 pg/mL (vs <150 pg/mL baseline) with co-administration
ManagementUse caution; consider alternative antifungal (fluconazole has weaker CYP3A4 inhibition); monitor for systemic steroid effects
FDA PI
Major
Ritonavir / Cobicistat
MechanismVery strong CYP3A4 inhibition
EffectMarkedly increased systemic corticosteroid exposure; risk of Cushing syndrome and adrenal suppression even at standard ICS doses
ManagementAvoid concurrent use if possible; if unavoidable, use the lowest effective ICS dose and monitor closely for HPA axis suppression
FDA PI
Major
Itraconazole / Clarithromycin
MechanismStrong CYP3A4 inhibition
EffectIncreased systemic mometasone levels with potential for adrenal suppression and steroid side effects
ManagementShort courses (<2 weeks) are typically tolerable; for longer courses, consider alternative agents (azithromycin, fluconazole)
FDA PI
Moderate
Erythromycin / Diltiazem / Verapamil
MechanismModerate CYP3A4 inhibition
EffectModest increase in systemic mometasone exposure; clinically significant effects unlikely at standard inhaled doses
ManagementGenerally safe for concurrent use; monitor for Cushingoid features if both are used chronically
Lexicomp
Moderate
Live vaccines
MechanismImmunosuppressive effect of corticosteroid (class effect)
EffectTheoretical risk of disseminated infection with live vaccines in patients on high-dose or prolonged ICS
ManagementStandard-dose inhaled mometasone is not a contraindication to vaccination; high-dose or concurrent systemic steroids warrant caution per ACIP recommendations
ACIP Guidelines
Minor
Other asthma medications (LABAs, montelukast, theophylline)
MechanismNo significant pharmacokinetic interaction identified
EffectNo unusual adverse reactions noted in clinical studies with concomitant use
ManagementNo dose adjustment needed; combination with LABAs is standard practice per GINA step 3–4
FDA PIMonitoring
-
Lung Function (FEV1 / PEF)
Baseline; 2–4 weeks after initiation; then every 3–12 months
Routine Spirometry confirms response to therapy and guides dose titration. Peak flow monitoring at home can detect early loss of control between clinic visits. -
Oropharyngeal Examination
Each visit
Routine Inspect for oral candidiasis (white plaques on tongue, palate, pharynx). Reinforce mouth rinsing technique at every encounter. -
Growth Velocity (Pediatric)
Every 3–6 months via stadiometry
Routine ICS class effect: mean reduction ~1 cm/year. Plot on growth chart; consider dose reduction if growth velocity declines significantly. -
Bone Mineral Density
Baseline if risk factors present; then per clinical judgment
Trigger-based DEXA scan in patients with osteoporosis risk factors (family history, chronic corticosteroid use, postmenopausal women, prolonged immobilization). Supplement with calcium and vitamin D as appropriate. -
Ophthalmological Assessment
Annually for long-term users; sooner if symptoms develop
Routine Screen for posterior subcapsular cataracts and glaucoma. Incidence: cataracts 0.9%, glaucoma/IOP elevation 0.3% in clinical trials. Refer to ophthalmology for any visual complaints. -
Adrenal Function
During steroid transition; perioperatively; if Cushingoid features develop
Trigger-based Morning cortisol or ACTH stimulation test when transferring from oral steroids, when using high-dose ICS chronically, or if symptoms of adrenal insufficiency emerge (fatigue, hypotension, nausea). -
Inhaler Technique
Every visit
Routine Verify correct use (rapid deep inhalation for DPI; slow deep inhalation for HFA MDI). Poor technique is the most common cause of apparent treatment failure.
Contraindications & Cautions
Absolute Contraindications
- Status asthmaticus or acute bronchospasm requiring intensive measures — mometasone inhaled is a controller, not a reliever; it has no role in the acute management of asthma emergencies.
- Known hypersensitivity to mometasone furoate or any excipient — includes anaphylaxis, angioedema, or severe rash with prior exposure.
- Milk protein allergy (Twisthaler only) — the Twisthaler contains lactose with trace levels of milk proteins; postmarketing reports of anaphylaxis in patients with milk protein allergy. The HFA formulation does not contain lactose and may be used in these patients.
Relative Contraindications (Specialist Input Recommended)
- Active pulmonary tuberculosis — ICS may worsen untreated TB. Document negative TB screening before initiating long-term ICS in high-risk populations.
- Active untreated systemic fungal, bacterial, viral, or parasitic infections — localized immunosuppression may impair clearance of existing respiratory infections.
- Ocular herpes simplex — corticosteroids may promote corneal perforation; obtain ophthalmology clearance.
- Recent transfer from high-dose systemic corticosteroids — ongoing adrenal insufficiency risk; manage jointly with endocrinology if complex taper is required.
Use with Caution
- Hepatic impairment — mometasone concentrations may increase with increasing severity of hepatic dysfunction due to reduced CYP3A4 metabolism.
- Concurrent use of strong CYP3A4 inhibitors — increased systemic exposure; monitor for Cushingoid features.
- Osteoporosis risk factors — prolonged ICS use contributes to bone density loss; ensure calcium and vitamin D supplementation.
- Patients with existing glaucoma or cataracts — ICS use may accelerate progression; schedule regular ophthalmological review.
- Immunocompromised patients — higher risk of serious infections; ensure varicella and measles immunity before starting ICS.
FDA Class-Wide Regulatory Warning
Adrenal Insufficiency Risk During Corticosteroid Transition
Deaths due to adrenal insufficiency have occurred in asthmatic patients during and after transfer from systemic corticosteroids to inhaled corticosteroids. Patients previously maintained on 20 mg/day or more of prednisone (or equivalent) may be particularly susceptible. Taper systemic steroids slowly (reduce prednisone by no more than 2.5 mg/week) and monitor for adrenal crisis signs during the transition period and for several months afterward. Patients should carry a medical identification card indicating the need for supplementary systemic steroids during physiological stress.
Patient Counselling
Purpose of Therapy
Mometasone inhaled is a controller medication that reduces airway inflammation to prevent asthma symptoms and attacks over time. It works by gradually calming the chronic inflammation that underlies persistent asthma. It does not provide instant relief during an asthma attack — patients must always have a separate rescue inhaler (such as albuterol) available for sudden symptoms.
How to Take
Use mometasone at the same time every day, whether or not symptoms are present. If prescribed once daily, the Twisthaler should be taken in the evening. For the HFA inhaler, prime with 4 sprays before first use or after 5 days of non-use. After every dose, rinse the mouth with water and spit it out — do not swallow. Full benefit may take 1 to 2 weeks to develop. The Twisthaler should be discarded 45 days after opening the foil pouch or when the dose counter reads “00,” whichever comes first.
Oral Thrush (Candidiasis)
Tell patient
White patches in the mouth or throat can develop from steroid deposition. Rinsing the mouth thoroughly with water and spitting after every dose is the most effective prevention measure. This occurs in roughly 4–6% of users.
Call prescriber
If white patches persist despite mouth rinsing, or if you develop throat pain or difficulty swallowing.
Not a Rescue Inhaler
Tell patient
This medication will not help during a sudden asthma attack. Always carry your rescue inhaler (e.g., albuterol) separately. Do not take extra doses of mometasone during an episode.
Call prescriber
If you need your rescue inhaler more than twice a week, if you wake at night with asthma symptoms, or if your breathing worsens despite regular use of mometasone.
Voice Changes (Dysphonia)
Tell patient
Hoarseness may develop from the medication depositing on the vocal cords. This is typically mild and reversible. Using the inhaler with correct technique and rinsing afterward helps reduce occurrence.
Call prescriber
If voice changes interfere with daily communication or persist beyond 2 weeks, the prescriber may adjust the dose or switch formulations.
Infection Susceptibility
Tell patient
Inhaled steroids can slightly reduce immune defenses. Avoid close contact with people who have active chickenpox or measles if you have not been vaccinated or have not had these illnesses.
Call prescriber
If you are exposed to chickenpox or measles, or if you develop signs of any significant infection (fever, worsening cough, unusual fatigue).
Growth in Children
Tell patient
Inhaled steroids may slightly slow growth in children. Your child’s height will be measured regularly to monitor this. The benefits of controlled asthma generally outweigh this small growth effect.
Call prescriber
If you are concerned about your child’s growth pattern, discuss at the next clinic visit so the dose can be reviewed.
Steroid Transition (Patients Switching from Oral Steroids)
Tell patient
Your oral steroid (e.g., prednisone) will be reduced gradually — do not stop it suddenly. During this transition, your body needs time to restart producing its own cortisol. Carry a medical ID card stating you may need emergency steroid cover.
Call prescriber
If you develop unusual tiredness, weakness, dizziness, nausea, or feel unwell during or after the taper. These may signal adrenal insufficiency and require urgent medical attention.
Sources
Regulatory (PI / SmPC)
- Asmanex Twisthaler (mometasone furoate inhalation powder) prescribing information. Merck Sharp & Dohme Corp. Revised 02/2021. FDA Label Primary source for dosing, adverse reaction incidence rates, contraindications, and pharmacokinetic data for the DPI formulation.
- Asmanex HFA (mometasone furoate) inhalation aerosol prescribing information. Merck Sharp & Dohme Corp. Revised 2019. FDA Label Source for HFA-specific dosing, pediatric safety data in ages 5–11, and adverse reaction tables for the MDI formulation.
- DailyMed — Asmanex Twisthaler label. National Library of Medicine. DailyMed Mirror of current FDA-approved labeling with structured data for Twisthaler.
Key Clinical Trials
- Bernstein DI, Berkowitz RB, Chervinsky P, et al. Dose-ranging study of a new steroid for asthma: mometasone furoate dry powder inhaler. Respir Med. 1999;93(9):603–612. DOI Pivotal dose-ranging study establishing efficacy of 200–800 mcg daily doses in adult asthma.
- Noonan M, Karpel JP, Bensch GW, et al. Comparison of once-daily to twice-daily treatment with mometasone furoate dry powder inhaler. Ann Allergy Asthma Immunol. 2001;86(1):36–43. DOI Demonstrated that once-daily evening dosing provides comparable FEV1 improvement to twice-daily regimens in mild-to-moderate asthma.
Guidelines
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2024 Update. GINA Reports International evidence-based guideline positioning ICS as step 2–5 controller therapy for persistent asthma.
- National Asthma Education and Prevention Program (NAEPP). Expert Panel Report 4: Guidelines for the Diagnosis and Management of Asthma. 2020. NHLBI US guideline providing step-care approach to asthma management; classifies mometasone DPI 220 mcg as medium-dose ICS.
Mechanistic / Basic Science
- Isogai M, Shimizu H, Esumi Y, et al. Binding affinities of mometasone furoate and related compounds including its metabolites for the glucocorticoid receptor of rat skin tissue. J Steroid Biochem Mol Biol. 1993;44(2):141–145. DOI Establishes mometasone receptor binding affinity relative to dexamethasone (12×), budesonide (5×), and fluticasone (1.5×).
- Derendorf H, Nave R, Drollmann A, et al. Relevance of pharmacokinetics and pharmacodynamics of inhaled corticosteroids to asthma. Eur Respir J. 2006;28(5):1042–1050. DOI Comprehensive review of ICS pharmacokinetic principles including the role of receptor affinity, lipophilicity, and systemic bioavailability.
Pharmacokinetics / Special Populations
- Affrime MB, Cuss F, Padhi D, et al. Bioavailability and metabolism of mometasone furoate following administration by metered-dose and dry-powder inhalers in healthy human volunteers. J Clin Pharmacol. 2000;40(11):1227–1236. DOI Key PK study establishing <1% systemic bioavailability via DPI and 4.5 h IV half-life; provided basis for FDA labeling claims.
- Daley-Yates PT, Bonsmann U, Engel S, et al. Comparative clinical pharmacology of mometasone furoate, fluticasone propionate and fluticasone furoate. Pulm Pharmacol Ther. 2022;76:102165. DOI Head-to-head PK comparison; measured absolute bioavailability of inhaled mometasone at ~11%, Vd ~499 L, and t½ 7.4 h (IV), providing context for the manufacturer’s <1% claim.
- Hochhaus G, Mollmann H, Derendorf H, Gonzalez-Rothi RJ. Pharmacokinetic/pharmacodynamic aspects of aerosol therapy using glucocorticoids as a model. J Clin Pharmacol. 1997;37(10):881–892. DOI Foundational review of ICS PK/PD modeling including protein binding and clearance parameters applicable to mometasone.