Effects of long-term exposure to ramelteon, a melatonin receptor agonist, on
endocrine function in adults with chronic insomnia.
Author(s): Richardson G, Wang-Weigand S.
Affiliation(s): Henry Ford Hospital, Sleep Disorders and Research Center, Detroit, MI 48202, USA.
grichar1@hfhs.org
Publication date & source: 2009, Hum Psychopharmacol. , 24(2):103-11
OBJECTIVE: To evaluate the effects of ramelteon, an MT(1)/MT(2) melatonin
receptor agonist used to treat insomnia, on endocrine function in adults with
chronic insomnia.
METHODS: This was a double-blind, placebo-controlled, trial of adults (18-45
years) with chronic insomnia. Subjects received either ramelteon 16 mg or placebo
nightly for 6 months. Hormonal measures of the thyroid, reproductive, and adrenal
axes were analyzed monthly and compared with baseline and placebo values.
RESULTS: While isolated changes were detected at some time points, there were no
consistent statistically significant differences between treatments on measures
of thyroid function (total T4, free T4, TSH, and total T3), adrenal function (AM
cortisol, and ACTH), or on most reproductive endocrine measures [LH, FSH,
estradiol (women), total, and free testosterone (men)]. Prolactin concentrations
were increased overall in women in the ramelteon group compared with placebo (p =
0.003). No clinical effects of elevated prolactin were reported; average
menstrual cycle length, duration of menses, and ovulation probability did not
differ between groups.
CONCLUSIONS: Long-term exposure to ramelteon 16 mg, a potent melatonin receptor
agonist, resulted in mild, transient increase in prolactin, in women only, that
were not associated with measurable reproductive effects. There were no
consistent changes in other endocrine measures.
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