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ABSTRACT: Prolactinoma is a benign tumor of the pituitary gland that leads to the overproduction of prolactin. It is the most common type of pituitary adenoma, accounting for approximately 50% of all pituitary tumors. The clinical presentation of prolactinoma varies depending on the level of prolactin elevation and the size of the tumor. In women, common symptoms include galactorrhea, amenorrhea, and infertility. Men may present with hypogonadism, decreased libido, erectile dysfunction, and gynecomastia. Large prolactinomas, known as macroadenomas, can cause mass effects such as headaches, visual disturbances due to compression of the optic chiasm, and hypopituitarism due to pressure on surrounding pituitary tissue. Understanding the pathogenesis of prolactinoma is crucial for developing effective treatments and improving patient outcomes. The development of prolactinomas involves a complex interplay of genetic, hormonal, and cellular factors. Treatment of prolactinoma aims to normalize prolactin levels, reduce tumor size, and alleviate symptoms. The first-line therapy is dopamine agonists, such as cabergoline and bromocriptine, with surgery and radiotherapy reserved for refractory cases. Furthermore, chemotherapeutic agent - temozolomide may be a treatment of choice in aggressive or malignant prolactinomas. By understanding the underlying mechanisms and different treatment methods, healthcare providers can optimize the management and outcomes for patients with prolactinoma.

Background: Along with the presence of the 2011 Endocrine Society Clinical Practice Guidelines and numerous large-scale studies on the treatment of hyperprolactinemia of different origin, there are some unresolved questions, ambiguous and sometimes contradictory points of view regarding the management of patients with prolactinomas. This overview is devoted to the analysis of the results of modern clinical studies and the approaches towards the management of hyperprolactinemia caused by prolactinoma. Materials and methods: A systematic research of the literature for the appropriate keywords published mainly for the last 10 years was done; also, a reference list of each selected article was analysed. We included to our review the articles reporting controversial issues or new data on the treatment of hyperprolactinemia. Results: The review describes various problems arising during the treatment of prolactinoma. The presence of primary and secondary dopamine agonist resistance in each case requires an individual approach, and sometimes may include the use of the antineoplastic agent temozolomide. The side effects of dopamine agonists are discussed, with quite rare ones, including valvulopathy, pathological psychological conditions and cerebrospinal rhinorrhea. The controversial issue of the duration and doses of the drug used to achieve a lasting effect in the treatment of prolactinomas is considered. There are some points connected with the frequency of relapses. Thus, recurrence is correlated to the duration of treatment with dopamine agonists, prolactin levels at diagnosis, and the initial tumor size. Metformin, somatostatin analogues, selective estrogen receptor modulators, tyrosine kinase inhibitors, inhibitors of the mammalian target of rapamycin, epidermal growth factor receptor antagonists are investigated nowadays as potential alternative methods of drug treatment of prolactinomas. Conclusion: Drug therapy with dopamine agonists makes it possible to achieve the desired results in the vast majority of patients. However, despite the proven safety of this group of medicines, the risk of side effects should still be taken into account. The therapy regimen should be determined by the clinical course of prolactinoma and the patient’s response to treatment. Other options of treatment should be considered in patients intolerant to medical therapy, with contraindication or resistance to dopamine agonists, in the case of a malignant tumor. The presence of refractory to any of the applied methods of treatment and aggressive prolactinomas leads to the search for new drugs.

Introduction: Cabergoline is the treatment of choice for prolactinomas. However, 10–20% of prolactinomas are resistant to cabergoline. Metformin, a biguanide widely used in the treatment of diabetes mellitus, has been shown to reduce prolactin secretion in various pituitary tumor-cell lineages both in vitro and in vivo and in human pituitary adenomas in vitro. The aim of this study is to test the effects of metformin addition to cabergoline treatment on prolactin levels in patients with resistant prolactinomas. Subjects and Methods: This is a prospective study performed in an outpatient clinic in a reference center. Ten adult patients (26–61 years) with prolactinomas (7 M), persistent hyperprolactinemia (38–386 ng/mL) under cabergoline treatment (2–7 mg/week) for at least 6 months (6–108 months), features of metabolic syndrome, and not taking metformin were included. Metformin (1.0–2.5 g v.o./day) was given according to patients' tolerance. Cabergoline doses were kept unchanged. Serum prolactin levels were measured before and after short- (30–60 days) and long-term (120–180 days) metformin treatment. Results: Mean prolactin levels did not show any significant changes (148 ± 39 vs. 138 ± 42 vs. 133 ± 39 ng/mL, before, at 30–60 days, and at 120–180 days, respectively, p = 0.196) after metformin (mean dose: 1.25 g/day; range: 1.0–2.0 g/day). No patient reached a normal prolactin level during metformin treatment. Two patients were considered partial responders for exhibiting prolactin decreases ≥50% at a single time point during metformin. Conclusion: Metformin addition to ongoing high-dose cabergoline treatment in patients with cabergoline-resistant prolactinomas failed to show a consistent inhibitory effect in serum prolactin levels. [ABSTRACT FROM AUTHOR]

Background: Along with the presence of the 2011 Endocrine Society Clinical Practice Guidelines and numerous large-scale studies on the treatment of hyperprolactinemia of different origin, there are some unresolved questions, ambiguous and sometimes contradictory points of view regarding the management of patients with prolactinomas. This overview is devoted to the analysis of the results of modern clinical studies and the approaches towards the management of hyperprolactinemia caused by prolactinoma., Materials and Methods: A systematic research of the literature for the appropriate keywords published mainly for the last 10 years was done; also, a reference list of each selected article was analysed. We included to our review the articles reporting controversial issues or new data on the treatment of hyperprolactinemia., Results: The review describes various problems arising during the treatment of prolactinoma. The presence of primary and secondary dopamine agonist resistance in each case requires an individual approach, and sometimes may include the use of the antineoplastic agent t emozolomide . The side effects of dopamine agonists are discussed, with quite rare ones, including valvulopathy, pathological psychological conditions and cerebrospinal rhinorrhea. The controversial issue of the duration and doses of the drug used to achieve a lasting effect in the treatment of prolactinomas is considered. There are some points connected with the frequency of relapses. Thus, recurrence is correlated to the duration of treatment with dopamine agonists, prolactin levels at diagnosis, and the initial tumor size. Metformin, somatostatin analogues, selective estrogen receptor modulators, tyrosine kinase inhibitors, inhibitors of the mammalian target of rapamycin, epidermal growth factor receptor antagonists are investigated nowadays as potential alternative methods of drug treatment of prolactinomas., Conclusion: Drug therapy with dopamine agonists makes it possible to achieve the desired results in the vast majority of patients. However, despite the proven safety of this group of medicines, the risk of side effects should still be taken into account. The therapy regimen should be determined by the clinical course of prolactinoma and the patient's response to treatment. Other options of treatment should be considered in patients intolerant to medical therapy, with contraindication or resistance to dopamine agonists, in the case of a malignant tumor. The presence of refractory to any of the applied methods of treatment and aggressive prolactinomas leads to the search for new drugs., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2023 Tetiana Tykhonova, Nadiya Barabash, Olena Kanishcheva. Published by Vilnius University Press.)