BINDING OF TEMOPORFIN TO THE LIPOPROTEIN FRACTIONS OF HUMAN SERUM

The binding of a new photosensitizer, temoporfin, to human serum lipop roteins was investigated. [C-14]-Temoporfin (0.1-10 mu g ml(-1)) was i ncubated with human serum for 30 min at room temperature or for 20 h a t 4 degrees C, prior to stepwise density flotation to separate the lip oprotein fractions. The distribution of the drug was independent of th e initial concentration or time and temperature of the incubation. The proportion of temoporfin in each fraction was: very low density lipop rotein 6%, low density lipoprotein 22%, lipoprotein(a) 17%, high densi ty lipoprotein 39% and lipoprotein deficient serum 16%. Autoradiograph y of agarose gels showed that the drug was associated with the lipopro tein in the fractions. Fractionation of plasma samples collected from a patient after an intravenous infusion of temoporfin revealed a bindi ng profile similar to that obtained in the in vitro study.