Photoprotective action of emollients in ultraviolet therapy of psoriasis

Abstract

An in vitro technique was used to measure the monochromatic protection factors of all emollients available on prescription. The action spectra for ultraviolet erythema and erythema in psoralen-sensitized skin were used to calculate, for each emollient, erythema protection factors relevant to UVB phototherapy and psoralen photochemotherapy, respectively. Of the 40 products tested, 22 (55%) had a UVB erythema protection factor > 1.2 at an application density of 2 microliters/cm2, and 31 (78%) at an application density of 4 microliters/cm2. Fewer products, 25% at 2 microliters/cm2 and 50% at 4 microliters/cm2, had a psoralen erythema protection factor > 1.2. A protection factor of 1.2 is equivalent to a reduction in ultraviolet dose of 17%, and is thus likely to be of clinical importance. These results allow a choice of emollient products which may improve response by increasing transmission of radiation through psoriasis scale without a concomitant decrease in transmission due to a sunscreening action.

Emollients and Photo(chemo)therapy: A Call for Caution

“…For this purpose, an in vitro technique designed for testing topical sunscreen preparations was used. A recent publication already showed, with the same technique, that emollients may indeed significantly modify the transmission of UV light [6], As this transmission may be enhanced or diminished, the term 'interaction factor' will be used rather than 'protection factor' as known for topical sunscreen preparations (i.e. sun protection factor).…”

A review on the extensive skin benefits of mineral oil

“…However, Schleider et al [44] reported that mineral oil only had a small effect (5-13% reduction of MED), whereas peanut oil and corn oil had no effect and petrolatum was actually beneficial. Equally, Hudson-Peacock et al [45] found a reduction in MED by 16% for mineral oil. Conversely, Behrens-Williams et al [46] found that an emulsion containing 35% mineral oil, 30% cetylstearyl alcohol and vaseline had no effect on UVB-induced erythema, and Otman et al [47] found that a variety of mineral oil-containing emulsions decreased the sensitivity to UV, but it should be realized that these formulations also contained soft paraffin waxes.…”

Effects of Different Emollients on Minimal Erythema Dose and Minimal Phototoxic Dose

“…Psoriasis gibi skuaml› hastal›klarda saç›lma normal görünümlü deriye göre daha fazla olmaktad›r 3 . Fototerapi ve fotokemoterapi s›ras›nda skuaml› plaklara nemlendiricilerin uygulanmas› ›fl›n›n saç›lmas›n› azaltarak etkili dalga boyunun canl› doku içerisine daha fazla penetre olmas›n› sa¤lamaktad›r 3,4 . Ayr›ca nemlendiriciler ve ultraviyolenin beraber kullan›lmas› ultraviyolenin (UV) deri üzerine olan kurutucu etkilerine karfl› deriyi korumaktad›r 5,6 .…”

“…Fototerapi ünitelerinde bu amaçla en s›k kullan›lan nemlendirici vazelindir 7,8 . Son zamanlarda baz› nemlendiricilerin ultraviyolenin deriye absorbsiyonunu engelleyerek tedaviyi olumsuz etkileyebildikleri görülmüfltür 4,9,10 . Bu çal›flmada fototerapi ünitelerinde s›k kullan›lan üç nemlendiricinin fototerapi/fotokemoterapi üzerine olumlu ya da olumsuz etkilerinin minimal eritem dozu (MED) ve minimal fototoksik doz (MFD) de¤erleri kullan›larak de¤erlendirilmesi amaçlanm›flt›r.…”

“…Fototerapi ve fotokemoterapi s›ras›nda s›k kullan›lan bu ajanlar›n tedavinin etkinli¤i üzerinde olumlu ya da olumsuz etkilerinin olup olmad›¤› konusu ise tart›flmal›d›r. UV tedavisi öncesi sürülen nemlendiricilerin derinin UV geçirgenli¤ini artt›rarak tedaviye olumlu etkilerinin olabilece¤ini düflünenlerin yan›s›ra, baz› nemlendiricilerin günefl koruyucu gibi etki göstererek UV geçirgenli¤ini azaltaca¤›n› düflünen yazarlar da vard›r 4,9,[11][12][13] . Bu çal›flmada, normal deriye fototerapi ve fotokemoterapi öncesi sürülen 3 farkl› nemlendiricinin MED ve MFD de¤erlerini nas›l etkiledi¤ini görmek amaçland›.…”