Prolactin Responsiveness to Nomifensine in Patients with Hyperprolactinemia of Tumorous or Uncertain Etiology*

Abstract

Nomifensine (Nom), an antidepressant which activates dopamine (DA) transmission mainly by inhibiting DA reuptake in the CNS, was assessed as a tool for distinguishing between tumorous and nontumorous hyperprolactinemia (Hper-PRL). The criterion adopted to define responsiveness to Nom was 30% or more suppression below baseline of the plasma PRL concentrations in samples collected within the 120-240 min postdrug interval. In 27 Hyper-PRL subjects in whom the existence of a tumor was subsequently established at surgery (25 prolactinoma, 1 ependymoma and 1 cholesteatoma) and in 13 subjects with roentgenographic alterations of the sella turcica unequivocal for the presence of pituitary tumors, oral Nom administration (200 mg) did not significantly lower baseline plasma PRL levels. In 46 Hyper-PRL subjects with no or only equivocal alterations of the sella turcica, Nom was effective in lowering plasma PRL in 14 subjects and ineffective in the remaining 32 subjects. It is of note that 13 of 14 Nom responders presented with radiologically normal sellas, whereas 16 of 32 Nom nonresponders presented with alterations, though minor, of the sella. Based on the response pattern to Nom of subjects with proven or probable tumors, the Nom nonresponders with intact sellas may harbor PRL tumors in an early stage of development. Closer follow-up for detection of the future development of a gross tumor is indicated in the group of patients with an abnormal test.