**2.2 Phototherapy in psoriasis**

*Healthcare Access - Regional Overviews*

potential systemic intoxication [28].

absorption, it should be avoided [25].

Salicylic acid triggers desquamation of corneocytes via lowering intracellular cohesion between the cells of the stratum corneum. It can be applied in creams,

The most notable adverse effect mentioned while using salicylic acid is the

It is safe to utilize during pregnancy, but in children, because of the systemic

Calcineurin inhibitors like tacrolimus, pimecrolimus and sirolimus supress the production of the inflammatory substances that seem accountable for the skin lesions in psoriasis. It is found in concentration of 0.3% gel or 0.5% cream [29]. As side effects, the most common is stinging sensation or contact dermatitis.

Topical retinoids tazarotene and bexarotene downregulate the turnover by altering transcription of genes in keratinocytes upon transportation within the nucleus, after binding to retinoic acid on the cell membrane. Furthermore, it reduces the hyperproliferation of keratinocytes; it regulates the differentiation and reduces

It can be applied as a cream in concentration of 0.1 and 0.05%, and when used on the nails, it seems to improve the onycholysis, pitting and salmon

It is contraindicated during pregnancy, but it is permitted to be used in

Topical corticosteroids display immunosuppressive, anti-inflammatory, antiproliferative and vasoactive action. They are categorized based on their potency, from low-potency to very potent corticosteroids. When considering the potency and the vehicle, disease severity, patient preference and sites of lesions must be taken into account [25]. They can be found as creams, ointments, gel, solutions, nail

Skin atrophy, telangiectasia as well as secondary infection are the most notable

Corticosteroids can be used during pregnancy but are not recommended in

Vitamin D analogues calcitriol, tacalcitol, maxacalcitol, paricalcitol and becocalcidiol decrease keratinocyte proliferation, inflammation or keratinization [33]. They can be applied on the skin, scalp or nails and are found as creams, ointments

The most common side effect is skin irritation. Very rare hypercalcemia, hyper-

calciuria and parathyroid hormone suppression have been described.

lacquer, foams or shampoos applied on the skin, scalp or nails.

ointments or lotions in concentrations between 2 and 6%.

It can be used in children older than 2 years old [25].

*2.1.5 Topical retinoids tazarotene and bexarotene*

*2.1.3 Salicylic acid*

*2.1.4 Calcineurin*

inflammation [30].

patches [25].

children [31].

side effects.

*2.1.7 Vitamin D*

or scalp lotions.

*2.1.6 Topical corticosteroids*

children under 2 years old [32].

**90**

Ultraviolets either from the sun or artificial light play a significant role in treating psoriasis mainly by supressing activated T cells, independently on the cell subpopulation involved in the disease [25]. It has been shown that NB-UVB is the most utilized phototherapeutical approach, inducing clinical and histopathological resolution of moderate-to-severe plaque psoriasis by exerting a cytotoxic effect on epidermal T cells [35, 36]. This apoptotic effect on T cells depends mostly on the penetration of the NB-UVB within the lesion, penetration that on the one hand depends on the wavelength and on the other the depth of the skin lesion [37]. Understanding that the T cells responsible for psoriasis are situated along the dermal-epidermal junction and within the epidermis, it has been determined that the optimal wavelength spectrum should range between 290 and 313 nm [38]. Currently, NB-UVB is the most common approached used worldwide, and it can be regarded as the gold standard in therapy for treating moderate-to-severe plaque psoriasis [39].
