Topical corticosteroids
Stoughton Vasoconstriction Assay 🡪 most common assay used for topical corticosteroids
Potency (4 potencies, 7 classes)
- Pregnancy Category C
- Lactation: caution when applied near breast
Group A
- Hydrocortisone, test tixocortol pivolate
Group B “ides”
- triamcinolone acetonide type, test budesonide or triamcinolone
Group C “sone”
- Betamethasone type, test dexamethasone
Group D1 “ates”
- Betamethasone diproprionate, test clobetasol-17-proprionate
Group D2
- Methylprednisolone aceponate type, test hydrocortisone butyrate
* Class A cross reacts with D2
Pharmacokinetics & potency depend on
- Structure of topical corticosteroids (Hydrocortisone is the backbone, ↑ with fluorination, esterification, halogenation)
- The vehicle
- Concentration of corticosteroids in vehicle
- Skin characteristics
Vehicle
- Propylene glycol & occlusive vehicles increase topical corticosteroids potency by increasing percutaneous absorption
Skin characteristics
- Topical corticosteroids penetration into skin correlates inversely with stratum corneum thickness
- Topical corticosteroids absorption increased in inflamed skin, skin hydration, relative humidity, & temperature
Diffuses into target cell, binds glucocorticoid receptor leading to gene regulation & transcription
1) Anti-inflammatory effects (bas above)
2) Antiproliferative + atrophic effects
- Decreased Keratinocyte mitotic activity, decreasing basal cell layer, stratum corneum & stratum granulosum
- Decreased fibroblast proliferation, migration, chemotaxis & protein synthesis (e.g. glycosaminoglycans)
Systemic effects
- As above
Dermatitis
- Lichen planus, pityriasis rosea, psoriasis
- Bullous
- Autoimmune connective tissue disease
- Neutrophilic
Others: alopecia areata, vitiligo, Chondrodermatitis nodularis helicis, granuloma annulare, lichen planopilaris, lichen sclerosus et atrophicus, cutaneous T-cell lymphoma, Morphea, Pruritic urticarial papules and plaques of pregnancy, sarcoidosis
Absolute
- Allergy to topical corticosteroids or vehicle
Relative
- Infection
- Infestation
- Ulceration
Systemic
- Hypothalamic pituitary adrenal axis
- Iatrogenic Cushing’s
- Growth retardation
- Risk factors for SE: young age, liver disease, renal disease, amount applied, body surface area, hydration of the skin, duration of treatment, potency, occlusion & lack of physician supervision
Cutaneous (local)
- Atrophy (weeks) often resolves 1-4 weeks except striae (irreversible)
- Addiction/rebound syndrome (flare after discontinuation on face & folds e.g. perioral dermatitis)
- Ocular effects
- Allergic contact dermatitis
- Risk factors: young age, potency, occlusion, & location
Vehicle related
- Itching, burning, stinging, urticarial, irritant contact dermatitis
- Folliculitis, Miliaria, acne/rosacea
- Allergic contact dermatitis (Pyoderma gangrenosum & sorbitan sesquioleate)
Tachyphylaxis
- Recovery after 3-4 days
- Compounding topical corticosteroids with some ingredients e.g. urea, salicylates, tar, antibiotics, antifungals: may affect topical corticosteroids stability, solubility, or cause irritant contact dermatitis /Allergic contact dermatitis
Therapeutic guidelines
- Choose corticosteroid based on potency, vehicle, brand name vs generic, price, cost-effectiveness & proper amount to dispense
- Potency: based on age, the type, severity, extent, location & expected duration
- Vehicle: consider location, potential for irritation & past allergic reactions
- Amount to dispense can be estimated using the fingertip unit: 1 fingertip unit = 0.5g enough for 2% BSA (2 patient palms)