Topical Corticosteroid Dosing, Mechanisms of Action, & Prescribing

Dosing of creams and ointments

A useful measuring technique that is most often used by dermatologists for topical application is the Finger-tip Unit (FTU), which is the amount of ointment expressed from a tube with a 5mm diameter nozzle, applied from the distal skin-crease to the tip of the index finger. [Cllin Exp Dermatol. 1991 Nov; 16(6):444-7.]

Estimating the Necessary Amount of Topical Corticosteroid for Adults

FTU = Finger-tip Unit [adapted from Long CC, Finaly AY: Clin Exp Dermatol 1991 Nov;16(6):444-7]

Estimating the Necessary Amount of Topical Corticosteroid for Children

FTU = Finger-tip Unit

[adapted from Long cc, Mills CM, Finaly AY: Br J Dermatol 1998;138:293-6]

Corticosteroid Mechanisms of Action

Epidermis

• Number of keratinocyte mitoses is diminished
• Stratum corneum thickness reduced
• Granular layer reduced or absent
• Melanocyte pigment production inhibited

[Warner M, Camisa C. Topical Corticosteroids. In: Comprehensive Dermatologic Drug Therapy, Wolverton SE, Editor. Philadelphia: W.B. Saunders Company, 2001; pp 548-77.]

Dermis

Early Atrophy

• Dermal volume reduced – decreased water content, loss of glycosaminoglycans
• Collagen and elastic fibers unchanged
• Late Atrophy (Continuation of the Atrophogenic Process)
• Dermal volume reuced
• Collagen and elastic fibers diminished and abnormally aggregated
• Hypoactive fibroblasts (as above)
• Dermal vessels fragile, due to loss of fibrous and ground substance support

[Warner M, Camisa C. Topical Corticosteroids. In: Comprehensive Dermatologic Drug Therapy, Wolverton SE, Editor. Philadelphia: W.B. Saunders Company, 2001; pp 548-77.]

Some general rules for prescribing topical corticosteroids

1. Very responsive diseases require mild or moderately potent formulations, less responsive diseases require potent or very potent formulations.
2. Mild formulations should only be used on the face, groin, axillae, genital and perianal areas.
3. Very potent formulations should be used for short periods of time (14-20 days) or intermittently to reduce adverse events.
4. Potent or very potent formulations are usually required on palms, soles and for lichenified and hypertrophic dermatoses.
5. Brief use of a more potent steroid achieves faster control of eczema and may result in less steroid use, compared with long use of inadequately potent preparations.
6. Occlusion is often needed on palms and soles to enhance penetration of the active molecule through the thicker stratum corneum.
7. Corticosteroids should not be used on ulcerated or atrophic skin.
8. Sudden discontinuation should be avoided after prolonged use to prevent rebound phenomenon.
9. When treating children, special guidelines should be followed to avoid the disadvantages of under-application or the occurrence of systemic or local adverse effects due to overdosage.
10. Laboratory tests for adrenal suppression are performed by some after long periods of therapy and/or treatment of large areas.

Precautions to consider

Carcinogenicity
Long-term animal studies to determine the carcinogenicity of topical corticosteroids have not been done.

Pregnancy
Topical corticosteroid preparations may cause fetal abnormalities in animals if used in large amounts with occlusive dressing for prolonged periods of time, or if more potent agents are used. Fetal abnormalities due to topical corticosteroids have not been documented in humans. It is not known whether topical corticosteroid molecules are excreted in breast milk, but no adverse effects during lactation have been reported. Topical corticosteroids are classified in FDA Pregnancy Category C.

[Warner M, Camisa C. Topical Corticosteroids. In: Comprehensive Dermatologic Drug Therapy, Wolverton SE, Editor. Philadelphia: W.B. Saunders Company, 2001; pp 548-77.]

Potential Local Side Effects

• Epidermal atrophy – the most common local side effect characterized by lax, wrinkled, thin skin with telangiectasias, purpura, striae, stellate psuedoscars, hypopigmentation or prominent deep vessels. It may be seen within the first 7 days of daily superpotent corticosteroid application under occlusion and within 2 weeks of daily application of a less potent corticosteroid. Significant atrophy is generally seen after many weeks or months of application, but striae have been observed on a man’s medial thighs after 2 weeks of proprietary combination of betamethasone dipropionate 0.05% and clotrimazole 1% cream. Most signs of cutaneous atrophy resolve by 1-4 weeks after discontinuation, however, striae are permanent.
• Steroid addiction/rebound – characterized by initial improvement with a topical corticosteroid, followed by lack of response after continue application, followed by a flare after corticosteroid withdrawal. The treated skin might appear erythematosus and the patient might report a burning sensation.
• Glaucoma/cataracts – penetration around the eyelid skin can be 36-40 times that of thicker skin such as the palm or sole. Prolonged use on cunjunctival tissue can lead to glaucoma, cataracts, reduced healing or traumatic ulcers, exacerbation of herpetic ulcers, and greater susceptibility to fungal and bacterial infections. Glaucoma and blindness have occurred after 12 years of intermittent use of 1% hydrocortisone cream for periorbital involvement of atopic dermatitis. Glaucoma also occurred in a patient with a history of hand eczema, for which he had been using 0.1% betamethasone-17-valerate cream at bedtime for the previous 7 years in varying frequency.
• Allergic or irritant contact dermatitis in response to a corticosteroid is suspected with a corticosteroid-sensitive dermatitis fails to respond readily to, or worsens with corticosteroid therapy.

[Comprehensive Dermatologic Drug Therapy, Wolverton SE, Editor. Philadelphia: W.B. Saunders Company, 2001; pp548-77.]

Topical steroids can be divided into 4 groups in terms of allergy, i.e., if a patient is allergic to one in the group, don’t use another one from the same group:

Group A

• Hydrocortisone
• Hydrocortisone acetate
• Cortisone acetate
• Tixocortol pivalate
• Prednisolone
• Methylprednisolone
• Prednisone

Group B

• Triamcinolone acetonide
• Triamcinolone alcohol
• Amcinonide
• Bedesonide
• Desonide
• Fluocinonide
• Fluocinolone acetonide
• Halcinonide

Group C

• Betamethasone
• Betamethasone sodium phosphate
• Dexamethasone
• Dexamethasone sodium phosphate
• Fluocortolone

Group D

• Hydrocortisone-17-butyrate
• Hydrocortisone-17-valerate
• Aclometasone dipropionate
• Betamethasone valerate
• Betamethasone dipropionate
• Prednicarbate
• Clobetasone-17-butyrate
• Clobetasol-17-propionate
• Fluocortolone caproate
• Fluocortolone pivalate
• Fluprednidene acetate