The pharmacokinetics and safety of porfimer after repeated administration 30-45 days apart to patients undergoing photodynamic therapy.

Background: Porfimer is an intravenous (i.v.) injectable photosensitizing agent used in the photodynamic treatment of tumours and of high-grade dysplasia in Barrett's oesophagus.

Aim: To assess the pharmacokinetics as well as the safety profiles of porfimer after a first and a second dose administered 30-45 days apart in patients undergoing photodynamic therapy.

Methods: Nineteen patients (16 with cholangiocarcinoma) were enrolled. Porfimer sodium was administered by i.v. injection over 3-5 min. Blood samples were collected prior to starting i.v. drug injection and postdose 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 h after the first administration to 725 h 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 nine 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 photodynamic therapy within 45 days.