PpIX production analysis from ALA solutions application for the treatment of recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) of the larynx is caused by human papillomavirus (HPV), resulting in symptoms such as hoarseness and respiratory difficulties. Surgical removal of the lesions is the standard treatment, but there is a high recurrence rate. Photodynamic therapy (PDT) may be a promising treatment due to its selectivity. Keratinized lesions were chemically induced in the tongues of rats to simulate histological changes of these lesions. Different formulations and application methods of the prodrug aminolevulinic acid (ALA) were tested: ALA with xanthan gum in gel form, ALA in saline solution, and ALA with DMSO in liquid form, with two application methods, directly on the lesion or in the throat, simulating systemic application and monitored for a period of 7 hours for the protoporphyrin IX production. These studies provide knowledge for the development of clinical protocols for the treatment of RRP.