Use of a compound of formula I wherein A represents O or NR.sub.N, wherein R.sub.N is hydrogen or lower alkyl, R is hydrogen or lower alkyl, R' is methyl, methoxy, ethoxy, amino, methylamino, dimethylamino, aminomethyl or methylthio, and Z is O or a bond, or a pharmaceutically acceptable salt thereof, alone or in combination with at least one compound selected from the group consisting of somatostatin or a synthetic derivative thereof, interferon, 5-fluorouracil, doxorubicin, cyclophosphamide, streptozotocin and a standard anti-diarrheal, for the preparation of a medicament for the treatment of carcinoid syndrome or at least one neuroendocrine tumor; a method of treating a warm-blooded animal, having carcinoid syndrome and/or at least one neuroendocrine tumor; a combination comprising a compound formula I as defined above and at least one compound selected from the group provided above; and to a commercial package comprising said combination.