Is the pain of topical photodynamic therapy with methyl aminolevulinate any different from that with 5-aminolaevulinic acid?

Topical photodynamic therapy (PDT) using 5-aminolaevulinic acid (ALA) or methyl aminolevulinate (MAL) is widely used in dermatology. It is commonly stated that MAL PDT is less painful than ALA PDT, although published data are conflicting. We report our experience of the use of ALA (4-6 h) (n = 20) and MAL (3 h) (n = 20) in 40 consecutive patients with Bowen's disease or superficial basal cell carcinoma, treated with PDT using an identical irradiation regime. Although there was a trend to higher pain scores with ALA PDT [visual analogue scale (VAS)score, median 4.50], this was not significantly different from that of MAL PDT (VAS score, median 3.55; P = 0.98), nor considered to be clinically important. Importantly, both ALA and MAL PDT regimes were fairly well tolerated in this patient cohort, supporting the use of these prodrugs in dermatological PDT.