A pharmacokinetic comparison in dogs of seven brands of 8-MOP and five new formulations.

A pharmacokinetic comparison was carried out with 7 commercially available brands of 8-methoxypsoralen and 5 new formulations. The purpose of the study was to determine the brand or formulation with the least interindividual variation and thus the best standardized 8-methoxypsoralen plasma levels. The experiment was performed on dogs and not on human subjects because each of the 12 preparations had to be given to the same individual. The 8-methoxypsoralen plasma levels were measured by high performance liquid chromatography. One commercial and one self-made formulation showed a significantly earlier peaking time and higher peak concentration than the other brands tested. At 1 hour after administration the same commercial preparation and 4 self-made formulations showed significantly higher plasma levels than the other formulations. At 2 h, however, 10 of the 12 brands or formulations did not show statistically significant differences in 8-methoxypsoralen plasma levels.