Calcipotriol pretreatment enhances methyl aminolevulinate‐induced protoporphyrin IX: an in vivo study in hairless mice

A randomized split-scalp study comparing calcipotriol-assisted methyl aminolaevulinate photodynamic therapy (MAL-PDT) with conventional MAL-PDT for the treatment of actinic keratosis

“…Bay et al . investigated a 3‐day pretreatment regimen with topical calcipotriol in UV‐exposed and non‐UV‐exposed murine skin . They observed that calcipotriol pretreatment increased PpIX fluorescence in both groups.…”

“…In our study, we applied calcipotriol ointment for 15 consecutive days with the aim to induce epidermal hyperplasia and thus increase MAL uptake . However, it is well known that increased MAL uptake and PpIX levels may also derive from the chronically UV‐exposed skin . The histopathological analyses did not show any difference between the sides in terms of epidermal thickness.…”

“…Vitamin D is a chemical substance that has the ability to promote keratinocyte differentiation. Indeed, in vitro studies have shown that differentiated keratinocytes express higher ALA‐induced intracellular PpIX concentrations, and thus become more susceptible to PDT …”

Short‐term chemical pretreatment cannot replace curettage in photodynamic therapy

“…Calcitriol/calcipotriol (CAL) is the hormonally active metabolite of vitamin D, and recent murine and human studies show that pretreatment with CAL significantly enhances PpIX fluorescence during MAL and ALA PDT . CAL is believed to mediate this enhancement through alterations in the expression of two enzymes in the heme synthesis; coproporphyrinogen expression is increased while ferrochelatase expression is decreased .…”

“…As curettage causes significant discomfort for patients, non‐invasive pretreatment procedures have been examined. Keratolytic pretreatment with 10% salicylic acid ointment for up to 2 weeks has been used in off‐label PDT treatment of psoriasis in several trials , and studies indicate that topical application of calcipotriol, a derivative of vitamin D, increases PpIX fluorescence both in vitro and in vivo . Additionally, our research group recently discovered that pretreatment with a super‐potent topical corticosteroid cream both reduced post‐PDT inflammation and showed a tendency to enhance PpIX fluorescence .…”