Six normal volunteers were tested to ascertain the dose-dependency and reproducibility
of the prolactin response to metoclopramide. Furthermore, pretreatments with 1-dopa
or cyproheptadine were performed. The same subjects also received intravenously 500
μg TRH. The oral administration of 5 mg metoclopramide produced a significant rise
in prolactin at 60 min and a maximal elevation at 90 min. The intravenous administration
of 5 mg metoclopramide produced a significant increment at 15 min and a maximal prolactin
level at 30 min. Peak prolactin levels following i.v. administration of the drug were
greater than those after oral administration. Intravenous administration of 1 mg of
metoclopramide produced a potential increment in plasma prolactin. Maximal prolactin
response to 1 mg i.v. metoclopramide was similar to that found with 500 μg i.v. TRH.
Reproducibilities of prolactin response were good in all doses and modes of administration
of metoclopramide. Pretreatment with 1-dopa inhibited the metoclopramide-induced prolactin
response, but pretreatment with cyproheptadine did not influence the prolactin response
to metoclopramide. Metoclopramide is a good and reproducible stimulator of prolactin
secretion.
Reproducibility
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Prolactin
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Metoclopramide
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L-Dopa
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Cyproheptadine
