Fluticasone

Overview

Fluticasone (Flovent®) is an inhaled glucocorticoid commonly used in veterinary medicine for the management of chronic inflammatory airway diseases in dogs and cats. It is administered via a metered-dose inhaler (MDI) using a species-appropriate spacer device to deliver the drug directly to the respiratory tract.

Unlike systemic corticosteroids, inhaled fluticasone provides localized anti-inflammatory effects within the airways while minimizing systemic exposure and associated adverse effects. However, some degree of systemic absorption may still occur, especially with long-term use.

Fluticasone is most commonly used for conditions such as feline asthma and chronic bronchitis in dogs. Peak effect takes about 10–14 days, so oral corticosteroid therapy is most commonly continued alongside it for the first 10–14 days and then tapered as the inhaled drug takes over.

Mechanism of Action (MOA): Fluticasone is a potent glucocorticoid that suppresses airway inflammation by inhibiting inflammatory cell infiltration, reducing cytokine production, and decreasing airway hyperresponsiveness. It binds the glucocorticoid receptor about 18 times more strongly than dexamethasone, which is what allows a microgram dose delivered into the airway to control inflammation locally.

Indications

Fluticasone is primarily used in dogs and cats as an inhaled anti-inflammatory agent for the management of chronic respiratory conditions. It is most appropriate for long-term control of airway inflammation rather than acute relief.

• Feline asthma: First-line inhaled therapy for long-term control of airway inflammation, reducing airway eosinophilia and bronchial responsiveness and improving coughing, wheezing and dyspnoea over time.
• Chronic bronchitis (dogs and cats): Used to control persistent airway inflammation, reduce cough frequency, and improve respiratory function.
• Chronic inflammatory airway disease: Helps decrease airway eosinophilia and inflammation in conditions characterized by ongoing lower airway irritation.
• Adjunct to systemic corticosteroids: Often used during transition from oral steroids to reduce systemic adverse effects while maintaining anti-inflammatory control.
• Long-term maintenance therapy: Suitable for chronic conditions requiring prolonged anti-inflammatory management with reduced systemic exposure compared to oral glucocorticoids.
• Feline idiopathic chronic rhinitis: An additional extra-label use in cats, given together with oral prednisolone which is then tapered once the inhaled drug is established. It uses a higher strength and a two-puff dose than the lower-airway regimens.

Dosage (Reference)

Dog

In dogs, fluticasone is administered via a metered-dose inhaler (MDI) using an appropriate spacer device. It is commonly introduced alongside systemic corticosteroids, which are gradually tapered over 10–14 days as inhaled therapy becomes effective.

Cat

In cats, fluticasone is widely used for feline asthma and chronic bronchitis. It is administered via an MDI with a feline-specific spacer device, and dosing is adjusted based on disease severity and clinical response.

Warnings & Precautions

Fluticasone is generally safer than systemic corticosteroids due to its local administration, but important precautions must be considered, especially with long-term use or improper technique.

• Not for acute bronchospasm: Fluticasone is not effective for emergency relief (e.g., acute asthma attacks); a fast-acting bronchodilator is required in these situations.
• Hypersensitivity: Contraindicated in animals with known hypersensitivity to fluticasone.
• HPA axis suppression: Prolonged use or higher doses may suppress the hypothalamic–pituitary–adrenal axis, especially with chronic therapy.
• Transition from systemic steroids: When switching from oral corticosteroids, gradual tapering is essential to avoid acute adrenal insufficiency. Supplemental systemic steroids may be required during stress or severe exacerbations.
• Local adverse effects (cats): Inhaled corticosteroids may lead to localized demodicosis affecting the muzzle or nasal planum.
• Systemic effects (chronic use): Although minimized, long-term use may still result in signs of iatrogenic hyperadrenocorticism (e.g., PU/PD, weight gain, panting).
• CYP3A4 interactions: Use cautiously with drugs that inhibit CYP3A4 (e.g., ketoconazole), as systemic fluticasone levels may increase.
• Delivery technique: Must be administered using a species-appropriate spacer device; improper technique significantly reduces drug efficacy.
• Delayed onset: Not suitable as a sole therapy for rapidly progressive disease; clinical improvement requires time.
• Pregnancy: Avoid in pregnancy unless the benefit to the dam clearly outweighs the risk. Given by injection to laboratory animals, fluticasone caused growth delays, cleft palate, omphalocele and delayed cranial ossification, and glucocorticoids as a class are contraindicated in pregnant animals.
• Nursing animals: It is not known whether the drug passes into milk, so use with caution in any nursing animal; safety in animals has not been established.
• Cardiac disease in cats: Corticosteroids given to cats may precipitate congestive heart failure — take particular care in a cat with a murmur, a gallop, or known cardiac disease.
• Diabetes and immunosuppression: Long-term steroid use increases the risk of diabetes mellitus and predisposes to immunosuppression; monitor blood glucose in animals on prolonged therapy.
• Existing infection: Use cautiously in animals with an existing oral or respiratory tract infection, because local immunosuppression may occur; chronic use is occasionally associated with local opportunistic infection.
• Paradoxical bronchospasm: An immediate increase in wheezing straight after dosing has been reported with inhaled fluticasone in humans. If it happens, stop the inhaler and treat with a fast-acting bronchodilator.
• Intradermal allergy testing: Inhaled corticosteroids can suppress intradermal allergy skin testing. A withdrawal of about 2 weeks before testing has been suggested, though it may not be necessary if serum IgE testing is used instead.
• Regulatory status: There is no veterinary-licensed fluticasone product — all use in dogs and cats is extra-label use of a human inhaler, with no established withdrawal times. It is also a class 4 substance under racing rules, so check competition regulations before treating a competing animal.

Drug Interactions

Clinically significant drug interactions with inhaled fluticasone are generally uncommon due to its low systemic absorption. However, interactions may still occur when used with drugs that affect its metabolism.

• CYP3A4 inhibitors (e.g., ketoconazole): May increase systemic fluticasone concentrations, potentially enhancing the risk of systemic corticosteroid effects.
• NSAIDs: Giving a corticosteroid together with an NSAID increases the risk of gastrointestinal injury.
• How much data exists: Interaction data specific to the inhaled route are sparse — the caution above is extrapolated from systemic corticosteroids rather than measured for the inhaler.

Side Effects & Overdose

Side Effects

Inhaled fluticasone is generally associated with fewer systemic adverse effects compared to oral or injectable corticosteroids, but both local and systemic effects may still occur, especially with long-term use.

• Upper respiratory effects: Pharyngitis and upper respiratory infection are the most likely adverse effects reported in people. In animals systemic absorption is low and side effects are not expected to be as severe as with systemic corticosteroids, but the equivalent local effect has not been characterised.
• HPA axis suppression: Chronic use may suppress cortisol production, particularly at higher doses or prolonged therapy.
• Iatrogenic hyperadrenocorticism (dogs): Signs may include weight gain, PU/PD, panting, alopecia, abdominal distension, and hepatomegaly.
• Localized demodicosis (cats): May develop on the muzzle or nasal planum with inhaled corticosteroid use.
• Dose relationship and recovery: Adrenal suppression is expected to recover once treatment is stopped, and a feline study found no significant suppression at 44, 110 or 220 µg every 12 hours.

Overdose

Acute overdose with inhaled fluticasone is unlikely to cause significant toxicity. However, chronic excessive dosing may result in systemic corticosteroid effects.

• Acute exposure: Typically minimal clinical effects; treatment is usually not required.
• Chronic overdose: May lead to HPA axis suppression and signs of iatrogenic hyperadrenocorticism.
• Management: Supportive care and dose adjustment; monitor for systemic corticosteroid effects.
• Poison-control consultation: For a suspected overdose, consult a 24-hour poison control service that provides veterinary-specific advice.

Key Notes

Practical clinical points that optimize the effective use of inhaled fluticasone in dogs and cats:

• Delivery device is essential: Fluticasone must be administered using a species-specific spacer (e.g., AeroDawg, AeroKat) to ensure proper drug deposition in the lungs.
• Breathing technique matters: After each actuation, keep the mask in place for 7–10 normal breaths, roughly 10 seconds — the delivery device must stay on the face for the whole count, not just the first breath.
• Consistency of use: Regular daily administration is required for long-term control of airway inflammation, and long-term therapy should be expected in these diseases.
• Cost considerations: Long-term therapy may be expensive, which can affect owner compliance.
• Inhaler handling: The inhaler should be shaken before use and handled properly to maintain accurate dosing.
• Spacer acclimation: Gradual introduction of the mask and positive reinforcement improves compliance, especially in cats.
• Canister lifespan: Each canister holds 120 metered actuations — about 2 months at 1 puff twice daily, and about a month at either 2 puffs every 12 hours or 1 puff four times daily.
• UK and US strengths: The same inhaler is labelled differently on either side of the Atlantic: 50, 125 and 250 µg per actuation outside the United States and 44, 110 and 220 µg inside it. The difference is where the dose is measured — at the metering valve or at the actuator nozzle — not a difference in the product.
• Storage: Store the canister between 15–30°C (59–86°F) with the mouthpiece down. Protect it from freezing and direct sunlight, keep it away from heat and open flame, and do not puncture or incinerate it.
• Dry powder inhalers are not suitable: Breath-activated dry powder inhalers (the Diskus-type devices, including the salmeterol combination) are not suitable for veterinary use — they need a deliberate forceful inhalation the patient cannot be asked for. Only the pressurised metered-dose aerosol works with a spacer and mask.
• Pharmacokinetics: About 30% of an inhaled dose reaches the circulation. The drug is metabolised by CYP3A4 to an essentially inactive metabolite, is 91% protein bound, and has a terminal half-life of about 8 hours with excretion mainly in the faeces.
• Inhaler versus nebulisation: Metered-dose inhalers do deposit drug in the airways of dogs breathing normally, sedated or not — but nebulisation deposits significantly more, which is worth knowing when a patient is not responding.
• Monitoring: Monitor the cough and other respiratory signs for efficacy, and watch for polyuria, polydipsia, polyphagia, weight gain or panting as signs of steroid excess. Owners should report any increase in coughing, sneezing, wheezing or respiratory distress. Where treatment is prolonged, monitor liver enzymes, blood glucose and renal function, and watch for signs of secondary infection. Where adrenal function is a concern, an ACTH stimulation test is the test that answers it.
• What the evidence supports: Inhaled and oral glucocorticoids have not been shown to differ in effectiveness for naturally occurring airway disease. In an 8-week feline study both eliminated clinical signs and reduced airway eosinophilia, with oral therapy producing the more robust improvement in airway mechanics. The reason to choose the inhaler is fewer systemic effects, not greater efficacy.
• Other names: Sold as Flovent HFA in the United States and as Flixotide Evohaler in the UK; also encountered as Flixonase, Cutovate and Flutivate, and combined with salmeterol as Advair Diskus.