Enhancement of 5-aminolevulinic acid-induced photodynamic therapy by a bioadhesive polymer

Using a topical formulation of 5-aminolevulinic acid (ALA), a mediated photodynamic therapy (PDT) was developed to treat oral precancerous and cancerous lesions. Several clinical results demonstrated that this special ALA preparation containing Carbopol 971P (CP971P), a bioadhesive polymer, resulted in a satisfactory PDT effect. It is believed that this PDT efficacy may be due to the increased bioadhesion of the preparation at the treatment site. We investigated whether there was a beneficial effect of CP971P on ALA PDT in vitro. CP971P was co-incubated with ALA in a cell culture system. The effect of CP971P was evaluated by monitoring the uptake of ALA, the fluorescence intensity of protoporphyrin IX, and the cell survival rate. The polymer was found to enhance the fluorescence intensity of protoporphyrin IX and the subsequent PDT effect when concurrently dosed with ALA. Our results showed that a formulation of ALA containing C971P could provide a better ALA PDT effect in cancer treatment.