Pharmacokinetics of cyclosporin in man following a single oral dose: relationship to body fat content.

We have investigated the pharmacokinetics of the immunosuppressive drug cyclosporin in 11 patients receiving regular dialysis therapy. After a single oral dose of cyclosporin, whole blood concentrations were measured at regular intervals for 24 h. Body fat content was estimated in each subject from the measurement of skin-fold thickness and mid-arm circumference. In ten of the 11 patients there was a relatively uniform response in the increase of cyclosporin blood concentration to a peak within the first 6 h. Calculated area under the blood concentration curve did not correlate with total bodyweight, but correlated strongly with body fat content as well as fat-free mass. This study suggests that more predictable blood concentrations of cyclosporin might be achieved if the initial dose were calculated on the basis of fat-free mass rather than total bodyweight.