ARTICLE | dermatology | unaffected skin. application of 20% ala for 3 hours
and subsequent treatment with red light (150 J/cm2 with a broadband lamp, 550–700 nm) caused phototoxicity in sebaceous follicles, sustained reduction of the size of sebaceous glands, and a reduction in the bacteria of the follicle. the results improved after four sessions11
. lP Pdl (595 nm, fluence 7–7.5 J/cm2 ) has been used as
an alternative light source for acne treatment for 45 minutes after the application of ala, with good effectiveness and minimal side-effects (erythema up to 2 days)36
. Its mode of action consists of targeting blood
vessels, photothermal action on the sebaceous glands, and photoactivation of endogenous porphyrins that are produced by the P. acnes in the pilosebacous follicle. the mode of action of Pdt in acne included direct thermal or photodynamic damage of the sebaceous gland, destruction of P. acnes, or enhancement of keratinocyte apoptosis in the pilosebaceous follicle. multiple sessions may be necessary to destroy the function of the sebaceous gland36
.
mal–Pdt has also been shown to be effective in inflammatory acne18, 35
. a 68% mean reduction in the
inflammatory acne lesions count has been reported. Side-effects included serious erythema, oedema (lasting up to 7 days), and pain of the treated skin35
. Furthermore,
a sterile pustular eruption, crusting and secondary infection have been reported on the treated areas18, 37 Patients undergoing Pdt frequently experience
.
moderate to severe pain in the treatment area during and after illumination. mal–Pdt has been show to be less painful than ala–Pdt when treating normal skin38
.
PDT has been shown to improve inflammatory acne on a short-term basis with up to 68% improvement of inflammatory lesions.
the pain may be managed by treating smaller areas during each session, and as a result, pain seems to lessen in subsequent treatments. the use of ice water can be used to cool the treated areas, and pauses during illumination have been reported as helpful (18). No scarring has been reported18
. a study comparing the effectiveness of ala–Pdt
versus mal–Pdt in the treatment of facial acne in 15 patients showed a 59% reduction of inflammatory lesions, with no difference between the two treatments. reported pain was similar in both treatments. However, ala–Pdt was associated with more long-lasting and severe side-effects37
. In non-randomised clinical trials it has been indicated
that the efficacy of IPl and Pdl may be improved when combined with photoactivation of exogenously applied ala19, 20, 38
. a randomised controlled trial showed that
mal–lPdl is slightly superior to lPdl for the treatment of inflammatory acne in 15 patients, with the median reduction of inflammatory lesions up to 80% at 12 weeks postoperatively with mal–lPdl39
. the split-face
intraindividual design has the advantage that patients serve as their own control and the disadvantage that possible external confounders are not accounted for39
.
lPdl treatments were performed in subpurpuric doses, and preoperative mal-incubation was associated with mild to moderate skin reactions that did not prevent patients from engaging in social activities39
. the supposed
mechanism of action for lPdl-mediated Pdt is a photochemical inactivation of P. acnes, which produces porphyrins, mainly coproporphyrins. these porphyrins are excited by specific wavelengths, which result in the formation of cytotoxic singlet oxygen, free radicals and bacterial killing39
.
PDT: clinical efficacy in acne Pdt has been shown to improve inflammatory acne on a short-term basis with up to 68% improvement of inflammatory lesions11, 17, 18, 35, 37
. two non-randomised controlled trials
. these response rates are
superior to those of randomised controlled trials with blue light sources that report short-term clearance rates of up to 50%4
reported IPl-assisted ala–Pdt to be more effective than placebo cream–IPl (87.7% reduction of inflammatory acne versus 66.8%), or IPl exposure alone19, 38
of short-term 30-minute preincubation with mal40 a blinded randomised controlled trial demonstrated
. another study did not find a beneficial effect .
48 ❚
that ala–Pdt and mal–Pdt showed no significant differences in the response rate for inflammatory acne vulgaris (59% decrease in inflammatory lesions 12 weeks after one Pdt treatment), but ala–Pdt was associated with more prolonged and severe adverse effects, including a sterile pustular eruption and crusting37
. July 2011 |
prime-journal.com
IMAGE DIKIIY /
SHUTTERSTOCK.COM
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