Topical corticosteroids are among the most commonly prescribed medication for inflammatory and hyperproliferative skin diseases.1 The mechanism of action of corticosteroids can be specific or nonspecific and involves the modulation of the skin at multiple levels including anti-inflammatory, immunosuppressive, vasoconstrictive and antiproliferative effects.

They are available in several formulations and can be categorised by potency, their formulations or the combination of active agents.

Understanding the subtle, yet dynamic differences of topical corticosteroid potencies and formulations can therefore ensure optimal therapeutic benefit to patients.

Steroids may differ in potency based on the vehicle in which they are formulated. Some vehicles should be used only on certain parts of the body. The absorption and potency of the therapy depend on the chemical structure of the corticosteroid and the vehicle used as a carrier for the active topical corticosteroid molecule which also helps with skin hydration and penetration.

Steroid Vehicles

Ointments:

Ointments provide more lubrication and occlusion than other preparations and are the most useful for treating dry or thick, hyperkeratotic lesions. Their occlusive nature also improves steroid absorption and skin hydration and penetration (absorption).2,3 Ointments should not be used on hairy areas and may cause maceration and folliculitis if used on intertriginous areas (e.g., groin, gluteal cleft, axilla, palms of the hands and soles of the feet). Their greasy nature may result in poor patient satisfaction and compliance.4

Creams:

Creams are water-based (mixes of water suspended in oil), spread easily and can be used on most areas of the body. They have good lubrication qualities and vanish into the skin, which makes them cosmetically appealing. They can be used in hairy and intertriginous areas and for wet lesions. They are also preferred for the treatment of acute inflammation because of their low occlusive ability and drying effect. Creams are generally less potent than ointments of the same medication, and they often contain preservatives, which can cause irritation, stinging, and allergic reaction. Acute exudative inflammation responds well to creams because of their drying effects. Creams are also useful in intertriginous areas where ointments may not be used. However, creams do not provide the occlusive effects that ointments provide.4

Lotions and gels:

Lotions and gels are the least greasy and occlusive of all topical steroid vehicles. Lotions contain alcohol, which has a drying effect on an oozing lesion. Lotions are useful for hairy areas because they penetrate easily and leave little residue. Gels have a jelly-like consistency and are beneficial for exudative inflammation, such as poison ivy. Gels dry quickly and can be applied on the scalp or other hairy areas and do not cause matting.4

 Foams, mousses and shampoos:

Foams, mousses, and shampoos are also effective vehicles for delivering steroids to the scalp. They are easily applied and spread readily, particularly in hairy areas. Foams are usually more expensive.4

Because hydration generally promotes steroid penetration, applying a topical steroid after a shower or bath improves effectiveness.5

Occlusion increases steroid penetration and can be used in combination with all vehicles. Simple plastic dressings (e.g., plastic wrap) result in a several-fold increase in steroid penetration compared with dry skin.6 Occlusive dressings are often used overnight and should not be applied to the face or intertriginous areas. Irritation, folliculitis, and infection can develop rapidly from occlusive dressings, and patients should be counselled to monitor the treatment site closely.4

Choosing a topical corticosteroid

Topical corticosteroids are effective for all skin disorders where hyperproliferation, inflammation and immunologic involvement are experienced. When using topical treatments, diagnosis as well as steroid potency, delivery vehicle, frequency of administration, duration of treatment and side effects need to be considered. Low-potency steroids are the safest for long-term use, on large surface areas, the face and in children. Medium-potency topical steroids are used for severe disease such as asteatotic eczema, atopic dermatitis, severe dermatitis, severe anal inflammation and lichen sclerosis of the vulva. High- and ultra-high potency agents should not be used on the face, groin, axillae and under occlusion, except in rare situations and then only for a short duration.3,5

 Use of a combination of a topical steroid, antibacterial agent and an antifungal

Ointments and creams containing a corticosteroid and an antibiotic are widely prescribed and is the treatment of choice in eczema of any type where there are clinical signs of bacterial infection. The combination can be considered for managing various clinical situations. These include secondary infections of eczema such as impetiginous crusting or postulation or where there is presence of S. aureus. A combination of corticosteroids with other antibiotics or antimicrobial agents may be indicated if Gram-negative rods or candida are present.14 In patients with a cutaneous fungal infection with intense pruritis and infection-induced dermatitis, treatment with a low- or medium-potency topical corticosteroid over a 7-10-day period is preferred along with a topical antifungal that can be continued until it is resolved.7

Use of fluocinolone acetonide cream or gel in the treatment of inflammatory dermatosis (Sylanar®)

Fluocinolone acetonide is a corticosteroid primarily used in dermatology to reduce skin inflammation and relieve itching. In a study on the local use of fluocinolone acetonide cream 0.25 % (Sylanar®) in the treatment of neurodermatitis disseminata (n=16), the agent was applied four times a day to flexural lesions of psoriasis, and the warm moist areas such as areas of lichen planus or psoriasis on the glans penis. The study found it to be effective in the treatment of neurodermatitis disseminata and neurodermatitis circumscripta and superior to hydrocortisone preparations.  Fluocinolone acetonide was also shown to be effective in open treatment and closed occlusive in dermatosis such as psoriasis vulgaris, pustular paronychial psoriasis and lichen planus.8

Use of fluocinolone acetonide and clioquinol for fungal skin infections (Sylanar-C®)

Clioquinol is a broad-spectrum antibacterial with anti-fungal properties which can reduce the growth of C. albicans and some other species of bacteria. A study to investigate the antimicrobial properties of an antifungal antibacterial and complex compound formulations has found that clioquinol can inhibit the growth of the majority of fungi including C. albicans and was shown to have the strongest antifungal activity compared to formulations such as 1 % natfitine 0.25 % ketoconazole.9

The combination of clioquinol and fluocinolone acetone is therefore useful in the control of candida infection in the perineum, the body folds and the ears. Also, in patients with seborrheic eczema with frequent infected lesions with staphylococci and candida, the combination would be appropriate.10,11

Use of fluocinolone acetonide and neomycin for inflammatory skin disease (Sylanar-N®)

Neomycin sulphate is an aminoglycoside antibiotic that has become established as one of the topical therapeutic agents of choice for the treatment of bacterial infections of the skin. In a study that investigated the efficacy of a combination of fluocinolone acetonide and neomycin vs fluocinolone acetonide alone, 47 % of patients harbouring S. aureus and treated with the combination became culturally negative in two weeks compared to only 15% of the patients treated with steroids alone.12 The results show that the addition of neomycin significantly reduced the incidence of bacterial regrowth with subsequent impetiginisation.13

 Key points

·         A corticosteroid-antibiotic combination is the treatment of choice in eczema of any type when there are clinical signs of bacterial infection
·         Topical antifungal agents are useful in treating fungal infections while corticosteroids are indicated for inflammatory dermatitis
·         Topical fluocinolone acetonide cream proved to be effective in the treatment of neurodermitis disseminata and neurodermatitis circumscripta and was superior to hydrocortisone preparations
·         The combination of fluocinolone acetonide and clioquinol is useful for the control of candida infection which may present in the perineum, the body folds and the ears.
·         Combination of fluocinolone acetonide and neomycin shows better clinical response than corticosteroid monotherapy in reducing the incidence of bacterial re-growth in inflammatory skin diseases.

 References:

  1. Aslam I, et al. What is new in the topical treatment of allergic skin disease. Current Opinion in Allergy and Clinical Immunology. 2014;14(5): 436-450
  2. Kwatra G. Topical Corticosteroids: Pharmacology. A Treatise on Topical Corticosteroids in Dermatology. 2017,11-22
  3. Rathi SK, et al. Rational and Ethical use of Topical Corticosteriods Based on Safety and Efficacy. Indian Dermatol. 2012 Jul-Aug; 57(4):251-259
  4. Ference, JD and Last, AR. Choosing Topical Corticosteroids Am Fam Physician. 2009 Jan 15;79(2):135-140.
  5. Pariser DM. Topical steroids: a guide for use in the elderly patient. Geriatrics. 1991;46(10):51-54,57-60,63.
  6. Drake LA, et al.  Guidelines of care for the use of topical glucocorticosteroids. J Am Acad Dermatol. 1996;35(4):615-619.
  7. Backlay L. Use of Topical Corticosteriods for Dermatologic Conditions Reviewed. Available online from: https://www.medscape.org/viewarticle/487108
  8. Mahindrakar MB, et al. Topical Corticosteroids Prescription Trends in Dermatology in Outpatient Unit of Tertiary Care Research Institute Hospital. South India. Indian Journal of Clinical and Experimental Dermatology. January-March 2016:2(1):8-11.
  9. Clinical studies with topical fluocinolone acetonide in the treatment of various dermatoses. Can Med Assoc. 1963;88:999-1003.
  10. You Z, et al. Clioquinol, an alternative antimicrobial agent against common pathogenic microbe. J Mycol Med. 2018:28(3):4 Knee, B, et al.92-501.
  11. Sneddon IB. Clinical Use of Topical Corticosteriods. Drugs. 1976; 11:193-199.
  12. Clioquinol. Available online from: https://pubchem.ncbi.nlm.nih.gov/compound/clioquinol
  13. Marples RR. Topical Steriod-Antibiotic Combinations: Archives of Dermatology. 1973; 108(2): 237.
  14. Lloyd KM. The value of neomycin in topical corticosteroid preparations. South Med J. 1969;62:94-96.