Short-term prolactin administration causes expressible galactorrhea but does not affect bone turnover: pilot data for a new lactation agent

Abstract

Background: Medications used to augment lactation increase prolactin secretion but can have intolerable side effects. We examined the biological activity of recombinant human prolactin (r-hPRL) as preliminary data for its use to augment lactation.

Methods: Healthy, non-postpartum women (n = 21) with regular menstrual cycles underwent a seven day randomized, double-blind, placebo-controlled trial of r-hPRL. Expressible galactorrhea, markers of bone turnover, calcium homeostasis and gonadal function were measured and side effects recorded.

Results: Prolactin levels increased during r-hPRL administration (20.0 +/- 2.8 to 231.7 +/- 48.9 microg/L at 6 hours; p < 0.05). Five of nine participants who received r-hPRL developed expressible galactorrhea (p < 0.001). Urinary deoxypyridinoline decreased and bone specific alkaline phosphatase increased in r-hPRL and placebo groups. Menstrual cycle lengths were not altered and side effects were similar between r-hPRL and placebo groups.

Conclusion: In summary, r-hPRL can cause expressible galactorrhea. Seven days of r-hPRL administration does not adversely affect bone turnover or menstrual cyclicity. Thus, r-hPRL may be a viable option for short-term lactation augmentation.

Trial registration: Clinical Trials.gov NCT00438490.

Figure 1

Prolactin levels after r-hPRL or placebo injections. Prolactin levels (mean ± SE) after administration of 60 μg/kg recombinant human prolactin (solid lines) or placebo (dotted lines) on the first (closed circles) and 7^th day of injections (open squares), over 6 hours. * designates significant differences in r-hPRL and placebo on the same day at p < 0.05.

Figure 2

Reproductive hormone concentrations during r-hPRL or placebo injections. LH, FSH and estradiol (E2) concentrations (mean ± SE) in normal women during 7 days of treatment with placebo (n = 12; black bars) and r-hPRL (n = 9; white bars) in the early (EFP), mid (MFP) and late follicular phase (LFP). There were no differences in hormone concentrations at any cycle stage between the two groups.