Flonase | Pharmacology Mentor

Generic Name

Flonase

Brand Names

for the intranasal glucocorticoid *fluticasone propionate*. It is FDA‑approved for the treatment of allergic rhinitis and nasal polyposis and is a cornerstone of evidence‑based nasal steroid therapy.

Mechanism

Fluticasone propionate is a potent synthetic glucocorticoid that diffuses across the nasal epithelium and binds to intracellular corticosteroid receptors. The receptor–ligand complex translocates to the nucleus and:

1. Suppresses pro‑inflammatory gene transcription (e.g., IL‑4, IL‑5, IL‑13, TNF‑α, COX‑2).
2. Induces anti‑inflammatory proteins such as lipocortin‑1 (annexin‑1) which inhibits phospholipase A₂.
3. Reduces chemokine production, limiting eosinophil migration to the nasal mucosa.
4. Diminishes mucous gland activity and vascular permeability, thereby decreasing rhinorrhea, congestion, and sneezing.

The net result is a local anti‑inflammatory effect with minimal systemic exposure due to first‑pass metabolism in the liver.

Pharmacokinetics

Parameter	Typical Value (Adults)	Notes
Absorption	~11 % systemic bioavailability	Rapid uptake from the nasal cavity
Distribution	Highly lipophilic; tissue‑to‑plasma Kp ≈ 200:1	Concentrated in nasal mucosa
Metabolism	1‑Hydroxylated by hepatic CYP3A4	Major pathway; polymorphic activity
Elimination	Primarily biliary; kidney excretion < 10 %	Terminal half‑life ≈ 7 h (systemic)
Peak plasma concentration	1–4 µg/L after a single 100 µg dose	Concentrations negligible with conventional dosing
Drug‑drug interactions	Strong CYP3A4 inhibitors ↑ systemic levels	Ritanserin, ketoconazole, HIV protease inhibitors
Special populations	Pediatric, geriatric: clearance similar; no dose adjustment needed	Pregnancy category C (use if clearly needed)

Indications

Seasonal allergic rhinitis (allergic rhinitis, AR)
Perennial allergic rhinitis (persistent AR)
Nasal polyposis (with or without asthma)
Adjunctive therapy for nasal symptoms in patients with asthma (reduces exacerbations)

Flonase may be used as a monotherapy or in combination with antihistamines or leukotriene receptor antagonists.

Contraindications

Known hypersensitivity to fluticasone, propionate ester, or any excipients (PEG, polysorbate).
Active fungal rhinosinusitis (Candidiasis) – consider topical antifungal before initiating.
Corticosteroid‑sensitive infections (e.g., tuberculosis, viral infections).
Use cautiously in patients with uncontrolled systemic steroid therapy.
Contraindicated in children < 4 yrs (no approved indication).
Potential ocular effects: glaucoma, cataracts; use with caution in susceptible individuals.

Dosing

Age Group	Dose	Frequency	Notes
Adults & Adolescents (≥12 yrs)	1–2 sprays per nostril	BID (morning & evening)	Start with 1 spray for 4 weeks; increase if needed
Pediatrics (4–11 yrs)	1 spray per nostril	BID	Start lower; titrate to 2 sprays if symptom control inadequate
Pregnancy	Same as adults	Use only if benefits outweigh risks	Labeled as Pregnancy Category C
Breastfeeding	No contraindication	Use with caution	Minimal transfer into milk

• Administration tip: Tilt the head slightly forward, inhale gently, and avoid forceful spraying to reduce systemic absorption.
• Max daily dose: 2 sprays/nostril (40 µg), do not exceed 4 sprays/nostril (80 µg) without clinician guidance.

Adverse Effects

Common (≤ 10 % incidence)
• Nasal irritation / dryness
• Headache
• Candidiasis (nasal fungal) – presents as white plaques or crusting
• Epistaxis
• Sore throat / cough

Serious (≤ 1 % incidence)
• Systemic corticosteroid‑related effects: adrenal suppression, Cushingoid features, growth suppression in children
• Ocular hypertension / glaucoma
• Severe fungal infection (rhinosinusitis)
• Allergic/anaphylactic reactions (rare)

Post‑marketing signals: Rare cases of visual disturbances reported with prolonged use (≤ 2 %); counsel patients to report any new ocular symptoms.

Monitoring

Parameter	Frequency	Rationale
Symptom control	Every 2–4 weeks	Dose titration guidance
Adrenal axis testing	Baseline (if >6 months use, especially high doses); repeat annually	Detect subclinical suppression
Growth velocity	Annually in children < 12 yrs	Avoid chronic suppression
Intra‑ocular pressure	Baseline and every 6–12 months	Screen for steroid‑induced glaucomatous changes
Nasal mucosa inspection	Each visit	Identify fungal infection, mucosal atrophy
Serum cortisol	Optional in case of systemic steroid suspicion	Objective evidence of suppression

Clinical Pearls

First‑line for AR: Flonase remains the gold standard due to high intra‑nasal concentration and low systemic side effects. It often replaces oral antihistamines for patients with persistent symptoms.
Candidiasis prophylaxis: Use intra‑nasal antifungal spray (nystatin or clotrimazole) prophylactically if you have a history of fungal infections or develop symptomatic candidiasis.
“Spare‑dose” strategy: If patients experience breakthrough symptoms, administer an extra spray during the flare rather than escalating the maintenance dose; this limits cumulative systemic exposure.
Timing matters: Using Flonase on an empty stomach (no food or drink) can slightly improve absorption; however, for patients who smoke, advise avoidance before use to prevent local irritation.
Drug interactions: Concomitant use of potent CYP3A4 inhibitors (rifampin, ketoconazole) can significantly increase systemic levels—adjustments may be necessary or consider an alternative steroid.
Special populations: For patients with asthma and nasal polyps, starting Flonase reduces sinusitis exacerbations and may lower rescue oral steroid use.
Cognitive side‑effects: Rare reports indicate mild fatigue or concentration issues in prolonged high‑dose users; recommend dose review if symptoms arise.
Sublingual alternatives: In patients with severe nasal obstruction, using a spray instead of dripping a viscous solution can reduce the risk of ocular exposure and systemic absorption.

*Prepared as an evidence‑based reference for clinicians and medical students. For full prescribing information, consult the FDA label and product monograph.*