Clinical study:Pharmacokinetics and safety of porfimer after repeated administrations 30 to 45 days apart to patients undergoing photodynamic therapy

Background: Porfimer is an intravenous injectable photosensitizing agent used in the photodynamic treatment of tumors and of high-grade dysplasia in Barrett's esophagus. Aim: In the present study, we assessed the pharmacokinetics as well as the safety profiles of porfimer after a first and a second dose administered 30 to 45 days apart in patients undergoing PDT. Methods: Nineteen patients (16 with cholangiocarcinoma) were enrolled. Porfimer sodium was administered by i.v. injection over 3-5 minutes. Blood samples were collected prior to starting i.v. drug injection and post-dose at different time points after the first and second administrations. Results: Porfimer exposure values after the second administration were statistically higher than those observed after the first administration, suggesting a slight accumulation of porfimer following repeated administration. The apparent mean elimination half-life of porfimer increased from 410 hr after the first administration to 725 hr after the second administration. The safety profiles of porfimer after a first and a second administration were similar and did not raise additional concern. Eight patients experienced 9 serious adverse events. Only photosensitivity was deemed study-drug related. Conclusion: Porfimer appears to display a safe and tolerable profile when used in patients requiring a second PDT within 45 days.