Thrombopoietic properties of 5-methoxytryptamine plus melatonin versus melatonin alone in the treatment of cancer-related thrombocytopenia

Recent studies have shown that the hematopoietic system is under neuroendoc rine control. In particular, thrombopoiesis has been proven to be stimulate d by melatonin, and the pineal indole has been shown to be: effective in th e treatment of thrombocytopenia resulting from different causes. At present , however. there are no data concerning the possible thrombopoietic activit y of pineal indoles other than melatonin. The present study was carried out to evaluate the effect of a concomitant administration of the pineal indol e 5-methoxytryptamine in patients with cancer-related thrombocytopenia who did not respond to melatonin alone. The present study included 30 patients, who were randomized to receive melatonin alone (20 mg/day orally in the ev ening) or melatonin plus 5-methoxytryptamine (1 mg/day. orally in the early afternoon). A normalization of platelet count was achieved in 5/14 (36%) p atients treated with melatonin plus 5-methoxytryptamine and in none of the patients treated with melatonin alone (P < 0.05). Moreover, mean platelet n umber significantly increased only in the patients treated with melatonin p lus 5-methoxytryptamine. This preliminary clinical study would suggest that 5-methoxytryptamine. a pineal indole, map also exert thrombopoietic activi ty. Further studies. however, will be required to establish whether 5-metho xytryptamine may play a direct thrombopoietic activity, or whether it may a ct by improving melatonin's efficacy.