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5‐Aminolevulinic Acid Photosensitization of Dysplastic Barrett's Esophagus: A Pharmacokinetic Study
Author(s) -
Ackroyd Roger,
Brown Nicola,
Ver David,
Roberts David,
Stephenson Timothy,
Marcus Stuart,
Stoddard Christopher,
Reed Malcolm
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb08266.x
Subject(s) - protoporphyrin ix , esophagus , vomiting , pharmacokinetics , gastroenterology , medicine , toxicity , oral administration , photodynamic therapy , porphyrin , nausea , pharmacology , phototoxicity , drug , pathology , chemistry , biochemistry , organic chemistry , in vitro
Photodynamic therapy (PDT) using 5‐aminolevulinic acid (ALA)‐induced protoporphyrin IX (PpIX) may have a role in the treatment of dysplastic Barrett's esophagus. Before ALA‐induced PDT can be used clinically, optimum treatment parameters must be established. In this study of 35 patients, the issues of drug dosage, time interval between drug and light delivery and side effects of oral ALA administration are addressed. Spectrofluoro‐metric analysis of tissue samples demonstrates that oral ALA administration induces porphyrin accumulation in esophageal tissues, with maximum levels at 4–6 h. High‐performance liquid chromatography confirms the identity of this porphyrin as PpIX, and fluorescence microscopy analysis demonstrates that it preferentially accumulates in the esophageal mucosa, rather than in the underlying stroma. Side effects of ALA administration included malaise, headache, photosensitivity, alopecia, transient derangement of liver function, nausea and vomiting. Fewer side effects and less hepatic toxicity was seen with 30 mg/kg than 50 mg/kg ALA. In conclusion, oral ALA administration induces preferential PpIX accumulation in the esophageal mucosa, with peak PpIX fluorescence noted at 4 h and minimal systemic toxicity at a dose of 30 mg/kg.