Tiapride-induced chronic hyperprolactinaemia: interference with the human menstrual cycle

Area of Science:

• Reproductive Endocrinology
• Neuroendocrinology
• Pharmacology

Background:

• Hyperprolactinemia, elevated prolactin levels, can disrupt normal reproductive function.
• Tiapride, a benzamide derivative, is known to block dopaminergic activity, potentially affecting prolactin secretion.

Purpose of the Study:

• To investigate the effects of tiapride-induced hyperprolactinemia on the hypothalamo-pituitary-ovarian axis in regularly menstruating volunteers.
• To assess the impact of varying prolactin levels on menstrual cycle hormones and corpus luteum function.

Main Methods:

• Oral administration of tiapride (100-200 mg/day) for three consecutive menstrual cycles.
• Daily blood sampling to measure luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), estradiol, and progesterone.
• Comparison of hormonal profiles during treatment cycles with a pre-treatment control cycle.

Main Results:

• Tiapride increased mean prolactin secretion in all subjects, with one experiencing sustained hyperprolactinemia.
• Hyperprolactinemia led to impaired corpus luteum function, evidenced by reduced luteal phase length (2-5 days shorter) in 5 cycles.
• One cycle showed questionable ovulation, and two were anovulatory; subsequent cycles after drug cessation indicated potential luteal phase inadequacy.

Conclusions:

• Non-permanent hyperprolactinemia can significantly impair the hypothalamo-pituitary-ovarian axis.
• The effects of hyperprolactinemia may extend to cycles following prolactin level normalization.
• Hyperprolactinemia appears to exert a dual impact on ovarian and hypothalamo-pituitary function, disrupting reproductive processes.