ASMANEX HFA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ASMANEX HFA (ASMANEX HFA).
Mometasone furoate is a corticosteroid that exerts anti-inflammatory effects by inhibiting multiple inflammatory cell types and mediators, including eosinophils, mast cells, macrophages, and lymphocytes, and reducing the release of pro-inflammatory cytokines and chemokines.
| Metabolism | Mometasone furoate is extensively metabolized in the liver via CYP3A4-mediated oxidation to form multiple metabolites, with negligible contribution from other CYP enzymes. |
| Excretion | Following oral inhalation, the absorbed fraction of mometasone furoate is extensively metabolized in the liver. Excretion is primarily via feces (approximately 74%) and urine (approximately 8%) as metabolites. Biliary excretion contributes to fecal elimination. |
| Half-life | The terminal elimination half-life of mometasone furoate following inhalation is approximately 25 hours (range 15–40 hours), reflecting slow absorption from the lungs and prolonged systemic clearance. |
| Protein binding | Mometasone furoate is 98–99% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | The volume of distribution is approximately 332 L (about 4.5 L/kg for a 70 kg individual), indicating extensive tissue distribution. |
| Bioavailability | The absolute bioavailability of mometasone furoate following oral inhalation is less than 1% due to extensive first-pass metabolism and low systemic absorption from the lung. |
| Onset of Action | Onset of action is within 1–2 weeks of regular use, with maximal benefit seen after 2–4 weeks of twice-daily dosing. No immediate bronchodilator effect; acute symptom relief is not expected. |
| Duration of Action | Duration of action is approximately 12 hours, supporting twice-daily dosing. Clinical effect persists with regular administration; however, the drug is not intended for acute bronchospasm relief. |
| Molecular Weight | 521.44 |
| Action Class | Corticosteroid, Inhaled |
2 inhalations (100 mcg each) twice daily orally, maximum 400 mcg/day.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No adjustment required. |
| Liver impairment | No adjustment required. |
| Pediatric use | For children aged 12 years and older: 2 inhalations (100 mcg each) twice daily. Safety and efficacy in children under 12 years not established. |
| Geriatric use | No specific dosage adjustment needed; use caution due to potential for increased sensitivity. |
| 1st trimester | No well-controlled studies; avoid unless benefit justifies risk. Inhaled corticosteroids do not show increased risk of malformations. |
| 2nd trimester | Use if clearly needed; monitor for potential effects on fetal growth and maternal glucose control. |
| 3rd trimester | Use if clearly needed; monitor for adrenal suppression in newborn if used near term. |
Clinical note
Comprehensive clinical and safety monograph for ASMANEX HFA (ASMANEX HFA).
| Placental transfer | Crosses placenta in animal studies; human data limited but systemic absorption is low after inhalation. |
| Breastfeeding | Inhaled mometasone is minimally absorbed; low levels in breast milk expected. Use with caution, especially in preterm infants. |
| Lactation Rating |
■ FDA Black Box Warning
Long-term use of inhaled corticosteroids may result in a reduction of growth velocity in children and adolescents. Patients should be monitored for growth suppression.
| Common Effects | Headache, Pharyngitis, Sinusitis, Upper respiratory tract infection, Dysphonia, Cough, Throat irritation, Nausea |
| Serious Effects | Oropharyngeal candidiasis, Adrenal insufficiency (with high doses or prolonged use), Increased risk of pneumonia in patients with COPD, Paradoxical bronchospasm, Hypersensitivity reactions (e.g., anaphylaxis, angioedema), Reduced growth velocity in pediatric patients, Glaucoma and cataracts (with long-term use) |
Hypersensitivity to mometasone furoate or any excipientsStatus asthmaticus (not for acute bronchospasm)
| Precautions | May cause localized Candida albicans infections of the mouth and pharynx, May increase risk of pneumonia in patients with COPD (not indicated for COPD), May cause systemic corticosteroid effects with high or prolonged use, including adrenal insufficiency, Should not be used for acute asthma exacerbations, May require dose adjustment in patients with hepatic impairment |
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| Teratogenic Risk | Insufficient human data; animal studies show no teratogenic effects at clinically relevant doses. Avoid use during first trimester unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal asthma control and fetal growth; periodic ultrasound for growth restriction if high doses required. |
| Fertility Effects | No evidence of impaired fertility in animal studies; no human data. |
| Food/Dietary | No significant food interactions. Grapefruit juice does not affect mometasone. Avoid alcohol as it may worsen asthma symptoms. |
| Clinical Pearls | Asmanex HFA (mometasone furoate) is an inhaled corticosteroid for maintenance treatment of asthma, not for acute bronchospasm. Rinse mouth after use to prevent oral candidiasis. Titrate to lowest effective dose. May reduce growth velocity in children; monitor growth. Not first-line for mild intermittent asthma. |
| Patient Advice | Use regularly as prescribed, not for sudden breathing problems. · Rinse mouth with water after each use, do not swallow. · Prime inhaler before first use or if not used for 5 days. · Keep track of number of actuations; discard after labeled number. · Avoid exposure to chickenpox or measles; notify doctor if exposed. · Do not stop abruptly; taper under medical supervision. |