Skin Conditions | November 4, 2014 | Author: The Super Pharmacist
Psoriasis is common, chronic disease of the skin that manifests as thickened, inflamed red areas often covered with silvery scales. These sores can be itchy and painful, and can lead to serious medical issues such as psoriatic arthritis. For the most individuals with psoriasis, the skin sores are the most troubling aspect of the disease. There is no cure for psoriasis, and skin sores can come and go over time. Currently, the best that patients can hope for is to rapidly treat skin lesions when they appear and prevent their recurrence over time.
No one quite knows why psoriasis happens. Scientists believe that the disease is caused by a combination of immunological, genetic, and environmental factors.1 In other words, the disease is not fully understood and, as such, directed treatment is not yet possible. Nevertheless, several treatments have been tried with varying degrees of success.
There are several ways to treat psoriasis; none of them perfect. Topical treatments, i.e. treatments applied to the skin over the affected area, are usually the first approach. Exposing the skin to ultraviolet light can also be effective in some individuals. In more serious cases, especially when psoriasis affects the joints, patients may receive oral or injected medications. Even in individuals who opt for oral medications usually also use a topical medication for outbreaks. The goal of treatment is control rather than cure.
Topical corticosteroids are often the first choice of treatment among physicians.2 Thicker plaques usually require a higher potency corticosteroid, such as 0.05% betamethasone. Lesions on the face are usually treated with a low potency corticosteroid cream, such as 1% hydrocortisone.
Corticosteroids are available as creams, ointments, lotions, gels, and in other vehicles. Creams may be more suitable for treating smaller lesions while a lotion is more suited to hairy areas such as the scalps.
Some preparations may be more suitable for psoriasis in certain areas of the body. For instance, betamethasone foam is more effective than betamethasone lotion in treating scalp psoriasis.4
Corticosteroids are often quite effective if chosen correctly (by the doctor) and used faithfully (by the patient). In fact, one of the biggest issues with corticosteroid treatment, and indeed with all topical treatments for psoriasis, is poor patient compliance. Patients do not use the topical treatments as directed. This is understandable since the medication can be expensive, especially when used chronically. Moreover, long-term use of topical corticosteroids increases the risk of side effects both on the skin and in the body.5
Emollients, such as petroleum jelly (Vasoline), are useful in keeping the skin soft and reducing the itchiness and tenderness of psoriatic sores. Emollients are inexpensive but only reduce symptoms of psoriasis; they do not make the sores go away faster.
Coal tar is relatively inexpensive and modestly effective in treating psoriasis, especially when combined with corticosteroids. It is available in a variety of forms including shampoos, creams, ointments, and lotions. As you might expect, the treatment is messy and sometimes smelly. Shampoos can change the color of one's hair, for example. However, in those who can tolerate these issues, coal tar is almost as effective as vitamin D analogues for treating psoriasis.6,7
Topical vitamin D analogues, drugs that are chemically related to vitamin D, include calcipotriol, calcitriol, and tacalcitol.
Of these, calcipotriol appears to be more effective than the other two. In fact, calcipotriol outperformed coal tar and anthralin for psoriasis, as well.13 Unfortunately, vitamin D analogues are known to cause skin irritation and calcipotriol is the worst offender among them. Fortunately for most patients, skin irritation is rarely the reason they stop using calcipotriol or other vitamin D analog.
Salicylic acid is a common treatment for acne, calluses, warts, and other diseases of the skin. It is useful because it is a keratinolytic, which means it breaks up and loosens the outer layer of skin. Salicylic acid’s role in psoriasis is largely as an adjunct therapy. It is often combined with other treatments, such as coal tar8 and corticosteroids9, rather than being effective on its own. Nonetheless, moderate concentrations of salicylic acid (i.e. 6% salicylic acid) administered over four months as an emollient foam effectively reduced psoriasis skin sores and was well tolerated by the study participants.10 The most common complaint of people who use salicylic acid is skin irritation, especially on surrounding skin.
Anthralin or dithranol is an effective treatment for psoriasis11,12, but skin irritation is very common and occurs in almost all users. To reduce this effect, physicians may prescribe a “short contact” regimen. These regimens usually start with very low doses of anthralin applied for only 10 minutes. Both the concentration of anthralin and the time of exposure is increased, depending on how well the patient tolerates the treatment. Like coal tar, anthralin may cause temporary staining on the skin and hair. It may cause permanent staining on clothes.12
Tazarotene is a topical psoriasis treatment that is related in structure to vitamin A (i.e, a retinoid). The vitamin A derivative is both safe and effective when compared to placebo in clinical trials. As with other treatments, a higher concentration outperforms lower concentrations, but the higher concentration of tazarotene, the higher the rate of side effects.14
There are two immunosuppressive drugs commonly used for the topical treatment of psoriasis, namely 0.1% tacrolimus and 1% pimecrolimus.15,16 While effective, they are probably less effective than commonly use topical corticosteroid treatments. Moreover, topical tacrolimus and pimecrolimus may increase the risk of dangerous cancers such as lymphoma and skin cancer.
In a recent systematic review and meta-analysis, researchers compared the most common topical psoriasis treatments available.7 This analysis compiled results on 177 clinical trials including nearly 35,000 study volunteers. The researchers found Vitamin D analogues and corticosteroids were each more effective than placebo.
Not surprisingly, higher potency corticosteroids are more effective than lower potency ones. In this meta-analysis, high potency corticosteroids appeared to be better than vitamin D analogues that were, in turn, better than low potency corticosteroids. Interestingly, the combination of a vitamin D analog and corticosteroid is even better than the either treatment alone.7
Coal tar, salicylic acid, dithranol (anthralin), and vitamin A were often used in combination with other treatments, so for the purposes of this review it is difficult to determine their effect individually. That said, the balance of studies indicate that coal tar, salicylic acid, and anthralin are effective.
In summary, most topical psoriasis treatments (vitamin D analogues, corticosteroids, anthralin, coal tar, salicylic acid) are at least modestly effective. The best topical psoriasis treatment is the one that the patient can tolerate, the patient uses as directed, and is affordable.
Raychaudhuri SK, Maverakis E, Raychaudhuri SP. Diagnosis and classification of psoriasis. Autoimmun Rev. Apr-May 2014;13(4-5):490-495.
1. Samarasekera EJ, Sawyer L, Wonderling D, Tucker R, Smith CH. Topical therapies for the treatment of plaque psoriasis: systematic review and network meta-analyses. Br J Dermatol. May 2013;168(5):954-967.
2. Clobetasol propionate (Clobex) spray for psoriasis. Med Lett Drugs Ther. Mar 27 2006;48(1231):27-28.
3. Franz TJ, Parsell DA, Halualani RM, Hannigan JF, Kalbach JP, Harkonen WS. Betamethasone valerate foam 0.12%: a novel vehicle with enhanced delivery and efficacy. Int J Dermatol. Aug 1999;38(8):628-632.
4. Menter A, Korman NJ, Elmets CA, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis. Section 3. Guidelines of care for the management and treatment of psoriasis with topical therapies. J Am Acad Dermatol. Apr 2009;60(4):643-659.
5. Tzaneva S, Honigsmann H, Tanew A. Observer-blind, randomized, intrapatient comparison of a novel 1% coal tar preparation (Exorex) and calcipotriol cream in the treatment of plaque type psoriasis. Br J Dermatol. Aug 2003;149(2):350-353.
6. Mason AR, Mason J, Cork M, Dooley G, Hancock H. Topical treatments for chronic plaque psoriasis. Cochrane Database Syst Rev. 2013;3:CD005028.
7. Singh P, Gupta S, Abidi A, Krishna A. Comparative evaluation of topical calcipotriol versus coal tar and salicylic acid ointment in chronic plaque psoriasis. J Drugs Dermatol. Aug 2013;12(8):868-873.
8. Tiplica GS, Salavastru CM. Mometasone furoate 0.1% and salicylic acid 5% vs. mometasone furoate 0.1% as sequential local therapy in psoriasis vulgaris. J Eur Acad Dermatol Venereol. Aug 2009;23(8):905-912.
9. Kircik L. Salicylic Acid 6% in an ammonium lactate emollient foam vehicle in the treatment of mild-to-moderate scalp psoriasis. J Drugs Dermatol. Mar 2011;10(3):270-273.
10. Oostveen AM, Beulens CA, van de Kerkhof PC, de Jong EM, Seyger MM. The effectiveness and safety of short-contact dithranol therapy in paediatric psoriasis: a prospective comparison of regular day care and day care with telemedicine. Br J Dermatol. Feb 2014;170(2):454-457.
11. Jekler J, Swanbeck G. One-minute dithranol therapy in psoriasis: a placebo-controlled paired comparative study. Acta Derm Venereol. Nov 1992;72(6):449-450.
12. Ashcroft DM, Po AL, Williams HC, Griffiths CE. Systematic review of comparative efficacy and tolerability of calcipotriol in treating chronic plaque psoriasis. BMJ. Apr 8 2000;320(7240):963-967.
13. Weinstein GD, Koo JY, Krueger GG, et al. Tazarotene cream in the treatment of psoriasis: Two multicenter, double-blind, randomized, vehicle-controlled studies of the safety and efficacy of tazarotene creams 0.05% and 0.1% applied once daily for 12 weeks. J Am Acad Dermatol. May 2003;48(5):760-767.
14. Lebwohl M, Freeman AK, Chapman MS, Feldman SR, Hartle JE, Henning A. Tacrolimus ointment is effective for facial and intertriginous psoriasis. J Am Acad Dermatol. Nov 2004;51(5):723-730.
15. Gribetz C, Ling M, Lebwohl M, et al. Pimecrolimus cream 1% in the treatment of intertriginous psoriasis: a double-blind, randomized study. J Am Acad Dermatol. Nov 2004;51(5):731-738.