Failure of pyridoxine to effect neuroleptic-induced hyperprolactinemia in psychotic patients.

The effects of acute and repeated administration of pyridoxine on serum prolactin levels were studied in 18 chronic schizophrenics, 10 women and 8 men, in whom hyperprolactinemia had been induced by long-term treatment with phenothiazines, haloperidol, sulpiride or clopentixol. The patients were divided into 5 groups: group 1 received 300 mg of the vitamin per os in a single dose; group 2 received 300 mg of the vitamin per os for 7 days; group 3 received 300 mg of the vitamin iv as a single bolus; group 4 received 600 mg of the vitamin iv as a single bolus; group 5 received 1200 mg of the vitamin per os in a single dose. Prolactin levels were examined before and 15, 30, 60, 90, 120 and 150 min after the single administration of pyridoxine, either iv or per os, and on days 3,5, 7 of the chronic administration. There was no decrease in prolactin levels either after oral or iv administration of the drug, given in single or repeated doses. Therefore, this treatment is not useful for the suppression of hyperprolactinemia induced by neuroleptics.