Update on Topical Approaches for Managing Scalp Psoriasis

G. E. Searles, MD, FRCPC, FACP
Associate Clinical Professor (Medicine), Division of Dermatology and Cutaneous Sciences, University of Alberta, Edmonton, AB, Canada

Introduction

Patients suffering from scalp psoriasis frequently seek medical care because of the persistent discomfort due to itching and social embarrassment caused by the visible flakes that are shed onto clothing. However, the presence of hair makes it challenging to apply medication to the scalp. In addition, available therapies often do not facilitate ease of use and may produce irritation and cosmetically unpleasant effects that can discourage patient adherence. Such therapeutic challenges often impede patients from deriving the full benefits from prescribed treatments. This article explores some of the current options and new advances in the topical management of this common skin disorder and offers strategies that may improve treatment outcomes.

Clinical Features

• Psoriasis can be limited to the scalp, but it frequently involves more than one area of the body.
  • Common concurrently affected sites include elbows, knees, buttocks, fingers, and nails.
• Between 50%-80% of all psoriasis patients have scalp involvement at some stage of their condition.¹
• The scalp may be the first site to show psoriasis; these lesions usually persist longer than those appearing elsewhere on the body.
• Psoriasis presents as well demarcated plaques that are characterized by scaling and erythema. Patients can experience varying degrees of itching and flaking.
  • Patches are commonly located on the occipital scalp, over the ears, and along the frontal hairline.
• The most common differential diagnosis is seborrheic dermatitis. Although it can mimic psoriasis, seborrheic dermatitis tends to be more diffuse, waxier in texture, and less scaly. It can also spread down the forehead and involve the nasolabial folds and eyebrows.
  • Psoriatic scales are generally thicker and drier in appearance; the skin may crack and bleed.
  • Scalp psoriasis can coexist with seborrheic dermatitis, and the persistence of yeast organisms in both conditions may share similar etiologies.
• Tinea or fungal infections frequently involve the hair shaft, leading to hair breakage, scaling, and swollen lymph nodes in the posterior cervical chain. It is more prevalent in children.

Therapeutic Considerations

• The presence of hair and scale build-up can interfere with medications reaching the scalp.
• Certain vehicles, such as ointments and creams, can be messy to apply and adhere to the hair shaft, resulting in a greasy appearance and prompting more frequent hair-washing. In addition, it is possible that not enough of the drug will actually reach the scalp, rendering the treatment ineffective.
• Medications should be applied to dry hair. Before application, comb hair to remove any loose scales. At affected areas, separate hair and gently rub the medication directly onto lesions.
• Issues surrounding cosmetic acceptability can lead to poor adherence, loss of effect, and patient dissatisfaction with the treatment.
• Convenient and/or simplified dosing can improve medication adherence.
  • A study involving psoriasis patients demonstrated substantially higher rates of adherence with oncedaily dosing (83%) vs. a twice-daily regimen (44%).²
• The vehicle can be as important as the active agent in achieving efficacy, tolerability, and treatment adherence.
  • Vehicles significantly impact the penetration and potency of active ingredients, i.e., lotions, gels and foams are superior to creams and ointments.
  • Alcohol-based solutions can sting and irritate.
  • Future management may include optimized vehicles (e.g., quick-break gel or foam, or lotions).

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Topical Treatment Options for Scalp Psoriasis

When compared with phototherapy and medicated shampoos, topical agents are most commonly prescribed for scalp psoriasis. Although there is a broad range of topical therapies, factors that can limit treatment options include irritation, convenience, ease of application, cosmetic acceptability, effectiveness for reducing itch and scale, and safety for prolonged use without loss of benefit. A therapeutic approach that addresses as many of these variables as possible will improve treatment outcomes.

OTC Treatments

• Many OTC combination preparations for scalp psoriasis utilize tar, salicylic acid, or zinc pyrithione; familiarity with these agents by pharmacists is useful for explaining their benefits and potential side-effects to patients.
• Salicylic acid is a keratolytic agent that promotes the release of scales and facilitates drug penetration. Salicylic acid is often used in combination with tars and corticosteroids. Skin irritation is a common side-effect.
• Zinc pyrithione may be helpful in reducing itching and flaking due to its antimicrobial properties.

Tars

• Tar compounds slow the proliferation of skin cells and reduce inflammation, itching, and scaling.
• Following treatment, the agent should be removed using any mild, unmedicated shampoo.
• Acceptance by patients is limited due to irritation, staining, and the odiferous quality of tars.
  • They can stain light-coloured hair and clothing.
• Tars can cause folliculitis and may be carcinogenic.

Corticosteroids

• Potent and ultrapotent corticosteroids, such as betamethasone dipropionate and clobetasol propionate, are widely used for their anti-inflammatory, immunosuppressive, and antiproliferative properties.
• They are commonly available as solutions, lotions, gels, and shampoos in a range of potencies.
• Prolonged use can result in tachyphylaxis.

Vitamin D3 Analogues (Calcipotriol/Calcipotriene)

• Calcipotriol promotes normal keratinization, suppresses inflammatory responses, and modulates both epidermal proliferation and differentiation.
• They are available in solution or gel formulations.
• There is no loss of effect with prolonged use.
• They are helpful for reducing scaling, but their usefulness for controlling erythema and itch is limited.
• To avoid the potential effects on calcium metabolism, limit use to 15g daily, or 100g weekly.³
• Due to the degradation of corticosteroids by vitamin D3 analogues, concurrent application should be avoided.

Calcipotriol + Corticosteroid Combination Therapy

• Stable commercial preparations of calcipotriol + betamethasone dipropionate have the dual benefit of controlling scalp psoriasis symptoms with a low risk of skin atrophy and without tachyphylaxis.^1,4
• Randomized double-blind, controlled studies showed that the two agents in combination have a more rapid onset of action and greater efficacy than monotherapy with either agent.^5,6
• A two-compound formulation of betamethasone dipropionate 0.5mg/g + calcipotriol 50ìg/g in a novel gel vehicle received Health Canada approval in November 2008 for the treatment of scalp psoriasis.
  • This new gel formulation achieved marked improvement to clearance in 92% of scalp psoriasis patients following once-daily use for up to 8 weeks.⁷
  • The gel vehicle enhances drug permeation, improves cosmetic acceptability, minimizes irritation, facilitates ease of use, is odourless, and offers oncedaily dosing.
  • Investigations reporting benefits of the new formulation did not use pretreatment or concomitant therapy with a keratolytic agent.^4-7 As such, adjunctive care for descaling is not required while patients are undergoing treatment.
  • To encourage adherence and allow for adequate absorption, the agent should be applied during the evening and remain on the scalp overnight.
  • For cosmetic reasons, patients can remove the gel in the morning by applying any mild, unmedicated shampoo to dry hair. Gently rub the shampoo into hair (in the treated area) to emulsify the gel medication, then wet hair, lather, and rinse. Hair washing is recommended for cosmetic and hygienic purposes, and is not required as part of therapy.
  • Recently published findings support the new agent’s safety, tolerability, and efficacy when used oncedaily, as needed, for up to 52 weeks.⁴
  • Studies report very similar rates of side-effects for all treatment groups, including placebo; the most common adverse event was pruritus.^3,5
  • To avoid the potential effects on calcium metabolism, limit use to 15g daily, or 100g weekly.³
• Safety for use in pregnant and nursing women, as well as in patients aged =18 years, has not been established. It is not recommended for these patient populations.

Considerations for Management

• Patients consider scalp psoriasis to be the most difficult aspect of their disease, which can lead to loss of selfesteem, social stigmatization, and even depression.
  • About 1 in 3 patients are self-conscious of their scalp psoriasis, and 1 in 5 report depressive symptoms.⁸
• Scratching and picking at scales can aggravate lesions and lead to spreading of the psoriatic plaques over a larger surface area (Koebner phenomenon).
• Management strategies (e.g., proper instructions for use, side-effects, and concomitant and OTC medications that can exacerbate psoriasis) should be reinforced.
  • Explain to patients that the major goals of treatment are to relieve the itching and reduce the scaling. Antihistamines are ineffective at controlling itch.
  • Wearing light-coloured clothing can minimize the visibility of flakes.
  • If necessary, patients may be advised to use OTC shampoos containing salicylic acid or tar to help soften and release the scales.
• Suggest patient participation in national organizations or web-based social networks. Psoriasis virtual communities can provide education and practical advice, as well as psychological and social support.

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Encouraging Treatment Adherence

• Nonadherence to treatment occurs in up to 40% of patients with psoriasis.⁹ Fears about treatment side-effects and the nuisance of using prescribed therapies can discourage adherence.
• Pharmacists can alleviate patient concerns regarding the side-effects from topical corticosteroid use (e.g., thinning of the skin) by explaining the benefits over risks when used properly.
• Pharmacists perform a vital educational role by imparting details on proper administration and therapeutic objectives. Nonadherence can be reduced when patients have an accurate understanding of their psoriasis and the selected treatment.
• Clinical strategies that can promote adherence include selecting fast-acting topical agents, treatments that facilitate ease of use (i.e., simple and convenient dosing), or combination agents that can enhance the rate and degree of improvement.

Conclusion

With the potential for escalating morbidity, diminished quality of life, and significant financial burden, it is essential to stem disease progression by managing both the physical and emotional aspects of psoriasis. Continuing efforts aimed at addressing unmet therapeutic needs have led to the development of new topical antipsoriatic therapies that are safer and more effective. The advent of two-compound agents that can target multiple pathogenic factors are proving to be particularly useful. The investigation of novel treatment combinations and new compounds for scalp psoriasis are ongoing in the quest to provide further enhancements in efficacy that will lead to improved patient adherence and treatment outcomes.

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References

1. Papp K, et al. J Eur Acad Dermatol Venereol 21(9):1151-60 (2007 Oct).
2. Zaghloul SS, et al. Arch Dermatol 140(4):408-14 (2004 Apr).
3. Xamiol® [calcipotriol and betamethasone dipropionate] product monograph. Thornhill, ON: LEO Pharma Inc. (2008 Nov).
4. Luger TA, et al. Dermatology 217(4):321-8 (2008).
5. Jemec GB, et al. J Am Acad Dermatol 59(3):455-63 (2008 Sep).
6. van de Kerkhof PC, et al. Br J Dermatol 160(1):170-6 (2009 Jan).
7. Buckley C, et al. Dermatology 217(2):107-13 (2008).
8. Chen SC, et al. Arch Dermatol 138(6):803-7 (2002 Jun).
9. Richards HL, et al. J Eur Acad Dermatol Venereol 20(4):370-9 (2006 Apr).

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