Prolactin Responsiveness to Repeated Decremental Doses of Sulpiride

Summary

The variation in the prolactin response to sulpiride was studied in six normal men by repeating the same dose of the drug (50 mg) after 24 hours and on three subsequent occasions, repeating this 2 day test at an interval of 6 days with progressively halved doses of sulpiride. A similar PRL response occurred on the first day of each test period and the peak response was highly significant (P < 0.001), occurring within 30 minutes. A gross blunting of the PRL responseon the second day of each period was noted throughout the study. The difference in Δ PRL between the first and second day of each period was highly significant (P < 0.001). The Δ PRL increment on the second day wasinversely proportional to the dose of sulpiride; the differences in Δ PRL between periods 1 and 3 and periods 1 and 4 being highly significant (P < 0.001). This study suggests that a much lower dose of sulpiride than that normally used is adequate to stimulate PRL secretion and that care must be taken in the timing of repeat testing.

Key-Words:

Prolactin - Sulpiride