Decreased urinary polyamines in patients with psoriasis treated with etretinate

Oral administration of the aromatic retinoid etretinate is effective therapy for psoriasis and other epidermal hyperproliferative disorders. Since polyamine metabolism is known to be important in cell growth and differentiation, we measured urinary levels of the polyamines putrescine, spermidine, and spermine as a reflection of cutaneous polyamine metabolism in 19 psoriatic patients treated with etretinate for 16 weeks. Using thin-layer chromatography, polyamine determinations were performed on urine collected pretherapy, during therapy, and 8 weeks after therapy was concluded. Good to excellent clearing of psoriasis occurred in 18 of 19 patients. All urinary polyamines showed a downward trend in the first week of therapy, prior to significant clinical improvement. At week 16 of therapy, the greatest reduction in mean urinary polyamine content occurred. Mean putrescine levels decreased from pretherapy to week 16 by 27% (p less than 0.001), mean spermidine values fell by 34% (p less than 0.001), and mean spermine levels declined by 37% (p = 0.005). These data are consistent with the hypothesis that etretinate inhibits polyamine biosynthesis.