ASTELIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ASTELIN (ASTELIN).
Azelastine, a phthalazinone derivative, exerts its effects by competitively inhibiting histamine H1-receptors, stabilizing mast cells, and reducing the release of inflammatory mediators. It also has anti-allergic properties including inhibition of leukotriene synthesis and suppression of eosinophil chemotaxis.
| Metabolism | Azelastine is metabolized primarily via cytochrome P450 (CYP) 3A4 and CYP2D6 pathways to its major active metabolite, desmethylazelastine. |
| Excretion | Renal excretion accounts for approximately 75% of the administered dose, with about 10% as unchanged drug. Fecal excretion is about 20%. |
| Half-life | The terminal elimination half-life of azelastine (active ingredient) is approximately 22 hours, supporting twice-daily dosing. |
| Protein binding | Approximately 88% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 14.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Intranasal: Absolute bioavailability is about 40% due to first-pass metabolism. Oral bioavailability is less than 10%. |
| Onset of Action | Intranasal: Onset of action is within 3 hours for relief of allergic rhinitis symptoms. |
| Duration of Action | Duration of action is approximately 12 hours, consistent with twice-daily dosing. Effects may persist for up to 24 hours in some patients. |
1 spray (137 mcg) per nostril twice daily (total daily dose: 548 mcg).
| Dosage form | SPRAY, METERED |
| Renal impairment | No adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (CrCl <15 mL/min). |
| Liver impairment | No adjustment indicated for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C). |
| Pediatric use | Children 6-11 years: 1 spray (137 mcg) per nostril twice daily. Children 12 years and older: same as adult. For children under 6 years: safety and efficacy not established. |
| Geriatric use | No specific dose adjustment. Use with caution due to potential for increased sensitivity or comorbidities; monitor for adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ASTELIN (ASTELIN).
| Breastfeeding | Unknown if azelastine (the active ingredient) is excreted in human breast milk. Intranasal route yields low systemic levels (<1% of dose); theoretical risk of anticholinergic effects in nursing infants. M/P ratio not available. Use with caution in breastfeeding women only if clearly needed. |
| Teratogenic Risk | Pregnancy Category C in original labeling; no adequate well-controlled studies in pregnant women. First trimester: limited data show no increased risk of major malformations in small studies. Second and third trimesters: may cause fetal harm due to anticholinergic effects (tachycardia, decreased GI motility). Intranasal administration results in minimal systemic absorption, reducing risk. Animal studies: no teratogenicity at doses up to 2.5 mg/kg/day (oral) in rats and 5 mg/kg/day in rabbits, but fetal toxicity (reduced weight, ossification delays) observed at maternally toxic doses. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to azelastine hydrochloride or any component of the formulation"]
| Precautions | ["Somnolence: May cause drowsiness; avoid driving or operating machinery if affected.","Impaired renal function: Use with caution in patients with renal impairment (CrCl < 25 mL/min).","Hepatic impairment: Monitor for adverse effects in severe hepatic disease.","Drug interactions: Effects may be additive with CNS depressants (alcohol, sedatives)."] |
| Food/Dietary | Alcohol may exacerbate the sedative effects of ASTELIN. No specific food restrictions reported. |
| Clinical Pearls |
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| Fetal Monitoring | No specific monitoring required beyond standard prenatal care. Assess fetal heart rate if maternal anticholinergic symptoms occur (tachycardia). Not recommended for use during pregnancy unless benefit outweighs risk. |
| Fertility Effects | No human studies on fertility. Animal studies: oral azelastine at 2.5 mg/kg/day in rats (approximately 25 times the maximum recommended daily intranasal dose on a mg/m² basis) caused no impairment of fertility. No known effect on human fertility. |
| ASTELIN (azelastine hydrochloride) is an intranasal antihistamine indicated for seasonal allergic rhinitis and vasomotor rhinitis. Onset of action occurs within 15-30 minutes. Bitter taste (dysgeusia) is a common adverse effect; instruct patients to tilt head forward and avoid sniffing immediately after administration to minimize this. Not recommended for acute asthma exacerbations. Use with caution in patients with hepatic impairment. |
| Patient Advice | Prime the spray by pumping 4 times or until a fine mist appears before first use or after 1 week of non-use. · Blow nose gently before each use. · Insert nozzle into nostril, tilt head forward, and close other nostril. · Do not sniff vigorously during or after spraying to avoid medication reaching the throat and causing bitter taste. · Common side effects include bitter taste, headache, nasal burning, or drowsiness. · Avoid alcohol consumption as it may increase drowsiness. · Report persistent nosebleeds or signs of infection. · Not for immediate relief of asthma symptoms; continue other asthma medications as prescribed. |