Mometasone is a synthetic corticosteroid used for its potent anti-inflammatory and immunosuppressive effects in the management of allergic and inflammatory conditions such as asthma, allergic rhinitis, and various skin disorders. It was developed for clinical use as a glucocorticoid receptor agonist that reduces inflammation by inhibiting the release of inflammatory mediators like cytokines, prostaglandins, and leukotrienes. Mometasone is widely used in multiple formulations, including nasal sprays, inhalers, and topical creams, and is valued for its strong local effect with minimal systemic absorption when used correctly. It is commonly included in long-term management regimens for chronic respiratory and dermatological conditions, helping to control symptoms such as nasal congestion, wheezing, and skin irritation.
BRAND NAMES
Nasonex (most widely known brand)
Asmanex Twisthaler
Asmanex HFA
Dulera (mometasone + formoterol inhaler for asthma)
MECHANISM OF ACTION
Mometasone is a synthetic corticosteroid that exerts its effects by binding to intracellular glucocorticoid receptors, forming a drug–receptor complex that regulates gene transcription in the nucleus. This action leads to suppression of inflammatory mediator production, including cytokines, prostaglandins, and leukotrienes, while also inhibiting phospholipase A2 activity and reducing arachidonic acid formation.
PHARMACOKINETICS
Absorption
Mometasone shows very low systemic absorption when administered via topical, nasal, or inhaled routes due to its high lipophilicity and extensive first-pass metabolism. After nasal or inhaled use, only a small fraction reaches systemic circulation, which helps minimize systemic side effects.
Distribution
Mometasone has a large volume of distribution, approximately ~200–400 L (or more in some reports), reflecting its high lipophilicity and extensive tissue binding.
Metabolism
Mometasone is extensively metabolized in the liver through hepatic metabolism, mainly via the cytochrome P450 system (primarily CYP3A4). It undergoes rapid biotransformation into inactive metabolites, which significantly reduces its systemic activity.
Elimination
Mometasone is eliminated primarily after hepatic metabolism into inactive metabolites, which are then excreted mainly through the bile into feces, with a smaller portion eliminated in the urine.
PHARMACODYNAMICS
Mometasone is a synthetic corticosteroid (glucocorticoid receptor agonist) that exerts strong anti-inflammatory, anti-allergic, and immunosuppressive effects. It works by binding to intracellular glucocorticoid receptors and regulating gene expression, leading to suppression of inflammatory mediators such as cytokines, prostaglandins, and leukotrienes.
ADMINISTRATION
Mometasone is administered in different formulations depending on the condition being treated. It is available as a nasal spray, inhalation powder/inhaler, and topical cream, ointment, or lotion. The nasal spray is used for allergic rhinitis, inhaled forms are used for asthma maintenance therapy, and topical forms are used for inflammatory skin conditions such as eczema and dermatitis.
DOSAGE AND STRENGTH
Dosage of mometasone depends on the formulation and indication. For nasal spray, adults commonly use 2 sprays in each nostril once daily (usually 50 mcg per spray), with maintenance doses adjusted as needed. For asthma inhalation, doses vary depending on severity, typically ranging from low to high daily inhaled microgram doses
DRUG INTERACTIONS
Mometasone has relatively few clinically significant drug interactions due to its low systemic absorption. However, caution is required when used with strong CYP3A4 inhibitors (such as ketoconazole or ritonavir), as these may increase systemic corticosteroid exposure.
CONTRAINDICATIONS
Mometasone is contraindicated in patients with known hypersensitivity to mometasone or any component of the formulation. It should not be used in untreated localized infections of the nasal passages, respiratory tract, or skin (such as fungal, bacterial, or viral infections) unless appropriate antimicrobial therapy is also given. Caution is required in patients with severe immunosuppression or active systemic infections.
SIDE EFFECTS
Nasal irritation or dryness (nasal spray)
Headache
Sore throat
Cough or throat irritation (inhalation form)
Skin irritation, burning, or itching (topical use)
Nosebleeds (epistaxis)
Rare: oral thrush (inhaled form)
Long-term: possible adrenal suppression or skin thinning (with prolonged high-dose use)
OVER DOSAGE
Mometasone overdose is rare because it is mainly used as a topical, nasal, or inhaled corticosteroid with very low systemic absorption. However, prolonged or excessive use at high doses can lead to systemic corticosteroid effects, particularly suppression of the hypothalamic–pituitary–adrenal (HPA) axis, resulting in adrenal insufficiency, fatigue, and weakness.
TOXICITY
Mometasone toxicity is uncommon due to low systemic absorption, but prolonged high-dose use or excessive exposure can lead to systemic corticosteroid effects such as adrenal suppression, Cushing-like symptoms, growth suppression in children, and immune suppression. Local toxicity may include skin thinning, delayed wound healing, and mucosal irritation. Overuse of inhaled forms may also increase the risk of oral fungal infections.
