A cross-over study with the two novel dopaminergic drugs cabergoline and quinagolide in hyperprolactinemic patients

How to manage intolerance to dopamine agonist in patients with prolactinoma

PURPOSE

Dopamine agonists (DA) are the gold-standard for prolactinoma and hyperprolactinemia treatment. Intolerance to DA leading to drug drop out occurs in 3 to 12% of cases. We provide here a review of published data about DA intolerance and present a case report concerning the use of intravaginal cabergoline.

METHODS

We review the literature on the definition, the pathogenesis, frequency and management of DA intolerance. In addition, the review provides strategies to enhance tolerability and avoid precocious clinical treatment withdrawal.

RESULTS

Cabergoline is often cited as the most tolerable DA and its side effects tend to ameliorate within days to weeks. Restarting the same drug at a lower dose or switching to another DA can be used in cases of intolerance. The vaginal route can be tried specifically if there are gastrointestinal side effects in the oral administration. Symptomatic treatment could be attempted, although mainly based on a strategy used in other diseases.

CONCLUSIONS

Due to limited data, no guidelines have been developed for the management of intolerance in DA treatment. The most frequent management is to perform transsphenoidal surgery. Nevertheless, this manuscript provides data derived from published literature and expert opinion, suggesting new approaches to this clinical issue.

The efficacy and safety of quinagolide in hyperprolactinemia treatment: A systematic review and meta-analysis

PURPOSE

Three dopamine agonists [bromocriptine, cabergoline, and quinagolide (CV)] have been used for hyperprolactinemia treatment for decades. Several studies have reviewed the efficacy and safety of bromocriptine and cabergoline. However, no systematic review or meta-analysis has discussed the efficacy and safety of CV in hyperprolactinemia and prolactinoma treatment.

METHODS

Five medical databases (PubMed, Web of Science, Embase, Scopus, and Cochrane Library) were searched up to 9 May 2022 to identify studies related to CV and hyperprolactinemia. A meta-analysis was implemented by using a forest plot, funnel plot, sensitivity analysis, meta-regression, and Egger's test via software R 4.0 and STATA 12.

RESULTS

A total of 1,211 studies were retrieved from the five medical databases, and 33 studies consisting of 827 patients were finally included in the analysis. The pooled proportions of patients with prolactin concentration normalization and tumor reduction (>50%) under CV treatment were 69% and 20%, respectively, with 95% confidence intervals of 61%-76% and 15%-28%, respectively. The pooled proportion of adverse effects was 13%, with a 95% confidence interval of 11%-16%.

CONCLUSION

Our study showed that CV is not less effective than cabergoline and bromocriptine in treating hyperprolactinemia, and the side effects were not significant. Hence, this drug could be considered an alternative first-line or rescue treatment in treating hyperprolactinemia in the future.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022347750.

Pharmaceuticals targeting signaling pathways of endometriosis as potential new medical treatment: A review

Endometriosis (EM) is defined as endometrial tissues found outside the uterus. Growth and development of endometriotic cells in ectopic sites can be promoted via multiple pathways, including MAPK/MEK/ERK, PI3K/Akt/mTOR, NF-κB, Rho/ROCK, reactive oxidative stress, tumor necrosis factor, transforming growth factor-β, Wnt/β-catenin, vascular endothelial growth factor, estrogen, and cytokines. The underlying pathophysiological mechanisms include proliferation, apoptosis, autophagy, migration, invasion, fibrosis, angiogenesis, oxidative stress, inflammation, and immune escape. Current medical treatments for EM are mainly hormonal and symptomatic, and thus the development of new, effective, and safe pharmaceuticals targeting specific molecular and signaling pathways is needed. Here, we systematically reviewed the literature focused on pharmaceuticals that specifically target the molecular and signaling pathways involved in the pathophysiology of EM. Potential drug targets, their upstream and downstream molecules with key aberrant signaling, and the regulatory mechanisms promoting the growth and development of endometriotic cells and tissues were discussed. Hormonal pharmaceuticals, including melatonin, exerts proapoptotic via regulating matrix metallopeptidase activity while nonhormonal pharmaceutical sorafenib exerts antiproliferative effect via MAPK/ERK pathway and antiangiogenesis activity via VEGF/VEGFR pathway. N-acetyl cysteine, curcumin, and ginsenoside exert antioxidant and anti-inflammatory effects via radical scavenging activity. Natural products have high efficacy with minimal side effects; for example, resveratrol and epigallocatechin gallate have multiple targets and provide synergistic efficacy to resolve the complexity of the pathophysiology of EM, showing promising efficacy in treating EM. Although new medical treatments are currently being developed, more detailed pharmacological studies and large sample size clinical trials are needed to confirm the efficacy and safety of these treatments in the near future.

Optimal timing of dopamine agonist withdrawal in patients with hyperprolactinemia: a systematic review and meta-analysis

PURPOSE

Dopamine agonists (DAs) are recommended as first-line treatment for patients with hyperprolactinemia. Generally, it is accepted that patients with hyperprolactinemia do not need lifelong medication, but the optimal timing for DA withdrawal has not been determined. The aim of this systematic review and meta-analysis is to assess the impact of DA withdrawal on the clinical outcomes of patients with hyperprolactinemia, and to explore possible factors affecting successful DA withdrawal.

METHODS

The databases of PubMed, Cochrane and EMBASE were searched up to May 2016.

RESULTS

The proportion of patients with persisting normoprolactinemia after DA withdrawal reached 36.6% in a random effects model (95% CI, 29.4-44.2%; I-squared: 82.5%). Data of stratified analysis showed that the success rate of drug withdrawal was high in patients using cabergoline (CAB) as the only treatment (41.2%; 95% CI 32.3-50.4%) and those using CAB over 24 months (48.7%; 95% CI 38.9-58.5%), especially in patients with idiopathic hyperprolactinemia (73.2%; 95% CI 55.6-87.7%). In addition, patients who received a low maintenance dose of CAB, and had a significant reduction in tumor size (over 50%) before withdrawal, were more likely to achieve success (51.5 and 49.4%, respectively).

CONCLUSION

The success rate of DA withdrawal has increased in recent years. Further, the success rate of CAB withdrawal was higher than that of bromocriptine, especially in patients with a duration of treatment longer than 24 months. Conclusively, the probability of success was higher in patients who received low-dose CAB maintenance treatment and those who achieved a significant reduction in tumor size before withdrawal.

Withdrawal of dopamine agonist therapy in prolactinomas: In which patients and when?

PURPOSE

The aim of the study was to assess the effect of dopamine agonist (DA) withdrawal, the current recurrence rate of hyperprolactinemia, and possible factors that predict recurrence in patients with prolactinoma.

METHODS

We evaluated DA withdrawal in 67 patients with prolactinoma (50 female/17 male) who received DA treatment for at least 2 years and showed normalization of prolactin (PRL) levels and tumor disappearance or ≥50 % tumor shrinkage, retrospectively. Accordingly, patients were divided into two groups as remission and recurrence groups, and factors that predict recurrence were evaluated.

RESULTS

The overall remission rate was 46 %; the remission ratios were 65 % in microprolactinomas and 36 % in macroprolactinomas. Remission rates were 39 % in the bromocriptine withdrawal group and 55 % in the cabergoline withdrawal group. The maximum tumor diameter and baseline PRL levels were significantly higher in the recurrence group (p = 0.001 and p = 0.003, respectively). The mean duration of DA therapy was significantly longer in the remission group (88.7 ± 48.1 and 66.7 ± 30.4 months, respectively, p = 0.026).The mean time to recurrence was 5.3 ± 3.2 months. The mean PRL levels at recurrence time were significantly lower than baseline PRL levels (p = 0.001).

CONCLUSION

The most important predictors of recurrence were maximum tumor diameter and baseline PRL levels in this study. The remission rate in our study group was higher, which was thought to be associated with the longer duration of DA treatment and that our patients were selected according to certain criteria. Despite these positive results, close monitoring is necessary for detection of early and late recurrence, especially within the first year after DA withdrawal.

Current drug withdrawal strategy in prolactinoma patients treated with cabergoline: a systematic review and meta-analysis

BACKGROUND

Cabergoline is a recommended first-line dopamine agonist for prolactinoma treatment, which is withdrawable for some cases. However, the optimal withdrawal strategy and the accurate recurrence rate associated with cabergoline withdrawal remains uncertain.

OBJECTIVE

To assess the current recurrence rate of hyperprolactinemia and possible favorable factors associated with cabergoline withdrawal in prolactinoma patients.

METHOD

The databases of PubMed, EMBASE, and Web of Science were searched up to May 2014 to identify studies containing data of recurrent hyperprolactinemia in prolactinoma patients after cabergoline withdrawal. Meta-analysis, including sensitivity analysis, meta-regression analysis, and subgroup analysis were performed.

RESULTS

When the patients who received cabergoline withdrawal were pooled, it was found that the hyperprolactinemia recurrence rate was 65% by a random effects meta-analysis [95% confidence interval 55-74%]. In a random effects meta-regression adjusting for optimal withdrawal strategies, CAB dose reduced to the lowest level before withdrawal was associated with treatment success (p = 0.006), whereas CAB treatment longer than 2 years showed no trend of effect (p = 0.587). Patients who received the lowest CAB dose and presented a significant reduction in tumor size before withdrawal were more likely to achieve the best success (p < 0.001).

CONCLUSIONS

Our meta-analysis shows that hyperprolactinemia recurs after cabergoline withdrawal in a majority of patients. The probability of success favors patients who have achieved normoprolactinemia and considerable reduction in tumor size by low dose of cabergoline treatment. In addition, our study further suggests that a beneficial strategy is associated with tapering CAB dose before withdrawal but not with CAB treatment duration longer than 2 years.

Medical treatment of prolactinomas

Prolactinomas, the most prevalent type of neuroendocrine disease, account for approximately 40% of all pituitary adenomas. The most important clinical problems associated with prolactinomas are hypogonadism, infertility and hyposexuality. In patients with macroprolactinomas, mass effects, including visual field defects, headaches and neurological disturbances, can also occur. The objectives of therapy are normalization of prolactin levels, to restore eugonadism, and reduction of tumor mass, both of which can be achieved in the majority of patients by treatment with dopamine agonists. Given their association with minimal morbidity, these drugs currently represent the mainstay of treatment for prolactinomas. Novel data indicate that these agents can be successfully withdrawn in a subset of patients after normalization of prolactin levels and tumor disappearance, which suggests the possibility that medical therapy may not be required throughout life. Nevertheless, multimodal therapy that involves surgery, radiotherapy or both may be necessary in some cases, such as patients who are resistant to the effects of dopamine agonists or for those with atypical prolactinomas. This Review reports on efficacy and safety of pharmacotherapy in patients with prolactinomas.

Hyperprolactinemia and prolactinomas

Any process interfering with dopamine synthesis, its transport to the pituitary gland, or its action at the level of lactotroph dopamine receptors can cause hyperprolactinemia. As described in this article, considering the complexity of prolactin regulation, many factors could cause hyperprolactinemia, and hyperprolactinemia can have clinical effects not only on the reproductive axis. Once any drug effects are excluded, prolactinomas are the most common cause of hyperprolactinemia. The most frequent symptom is hypogonadism in both genders. Medical and surgical therapies generally have excellent results, and most prolactinomas are well controlled or even cured in some cases.

Advances in the treatment of prolactinomas

Prolactinomas account for approximately 40% of all pituitary adenomas and are an important cause of hypogonadism and infertility. The ultimate goal of therapy for prolactinomas is restoration or achievement of eugonadism through the normalization of hyperprolactinemia and control of tumor mass. Medical therapy with dopamine agonists is highly effective in the majority of cases and represents the mainstay of therapy. Recent data indicating successful withdrawal of these agents in a subset of patients challenge the previously held concept that medical therapy is a lifelong requirement. Complicated situations, such as those encountered in resistance to dopamine agonists, pregnancy, and giant or malignant prolactinomas, may require multimodal therapy involving surgery, radiotherapy, or both. Progress in elucidating the mechanisms underlying the pathogenesis of prolactinomas may enable future development of novel molecular therapies for treatment-resistant cases. This review provides a critical analysis of the efficacy and safety of the various modes of therapy available for the treatment of patients with prolactinomas with an emphasis on challenging situations, a discussion of the data regarding withdrawal of medical therapy, and a foreshadowing of novel approaches to therapy that may become available in the future.

Current treatment issues in female hyperprolactinaemia

High prolactin levels can occur as a physiological condition in females who are pregnant or lactating. As a pathological condition, hyperprolactinaemia is associated with gonadal dysfunction, infertility and an increased risk of long-term complications including osteoporosis. The most frequent cause of persistent hyperprolactinaemia is the presence of a micro- (<10mm diameter) or macroprolactinoma (>/=10mm). These pituitary tumours may produce an excessive amount of prolactin or disrupt the normal delivery of dopamine from the hypothalamus to the pituitary; prolactin secretion from the pituitary is inhibited by dopamine released from neurones in the hypothalamus. Medications including anti-psychotics can induce hyperprolactinaemia, while idiopathic hyperprolactinaemia accounts for 30-40% of cases. The prevalence of hyperprolactinaemia is difficult to establish as not all sufferers are symptomatic or concerned by their symptoms and may remain undiagnosed. Symptoms of hyperprolactinaemia include signs of hypogonadism, with oligomenorrhoea, amenorrhoea and galactorrhoea frequently observed. Pharmacological intervention should be considered the first line therapy and involves the use of dopamine agonists to reduce tumour size and prolactin levels. Bromocriptine has the longest history of use and is a well-established, inexpensive, safe and effective therapy option. However, bromocriptine requires multiple daily dosing and some patients are resistant or intolerant to this therapy. The two newer dopamine agonists, quinagolide and cabergoline, provide more effective and better tolerated treatments compared with bromocriptine and may offer effective therapies for bromocriptine-resistant or intolerant patients. Quinagolide can be used until pregnancy is confirmed and may result in improved compliance in females wishing to become pregnant. For patients with hyperprolactinaemia, pregnancy is safe and can frequently be beneficial, inducing a decrease in prolactin levels. There does not appear to be any increased risk of abortion, malformations or multiple births in pregnancies achieved with bromocriptine and this dopamine agonist can be used safely during pregnancy. Surgery should be considered only in certain circumstances, and for the majority of patients, dopamine agonists will be sufficient to alleviate symptoms and restore normal prolactin levels.

Prolactin and reproductive medicine

PURPOSE OF REVIEW

This review aims to summarize current knowledge about prolactin, and outlines recent information that affects the management of patients with hyperprolactinaemia.

RECENT FINDINGS

The actions of prolactin have been clarified by studies of prolactin-receptor-deficient mice, which have a clear phenotype of reproductive failure at multiple sites. The treatment of patients with hyperprolactinaemia or prolactinoma is largely achieved using dopamine agonist drugs, which induce the shrinkage of pituitary prolactinomas as well as control of the endocrine syndrome. Recent findings indicate that successful cabergoline treatment may be able to induce long-term remission, allowing drug withdrawal in a substantial proportion of patients.

SUMMARY

At present, dopamine agonist drugs remain the best treatment for hyperprolactinaemic patients, and can help most affected women achieve pregnancy. Future work is likely to help understand the basis of long-term remission in patients with pituitary prolactinomas.

Dopamine receptor agonists for treating prolactinomas

Prolactinomas are the most common hormone-secreting pituitary tumours and cause infertility and gonadal and sexual dysfunction in both sexes. The approach to prolactinomas has changed in the last 25 years thanks to the availability of dopaminergic drugs characterised by a potent prolactin-inhibitory effect, a tumour shrinking effect associated with a satisfactory tolerability. In more recent years, cabergoline 1-[(6-allelylergolin-8beta-yl)carbonyl]-1-[3-(dimethylamino) propyl]-3-ethyl-urea an ergoline derivative with potent, selective and long-lasting inhibitory activity on prolactin release, has been used to suppress prolactin secretion in women with hyperprolactinaemia. Cabergoline was shown to be significantly more effective than bromocriptine in inducing a complete biochemical response and clinical efficacy and was better tolerated than bromocriptine in the majority of patients. Notable tumour shrinkage until tumour disappearance was observed during cabergoline treatment in most patients with macroprolactinoma and it was also proven effective in patients resistant to or with a poor response to bromocriptine. In view of the limited data on cabergoline-associated pregnancies and the long half-life of the drug, it is currently recommended that women hoping to become pregnant, once ovulatory cycles have been established, should discontinue cabergoline therapy 1 month before they intend to conceive. However, no data concerning negative effects on pregnancy or offspring have been reported. The great efficacy of this compound together with its excellent tolerability makes this drug the current treatment of choice for the majority of patients with hyperprolactinaemic disorders.

A randomized cross-over study comparing cabergoline and quinagolide in the treatment of hyperprolactinemic patients

Quinagolide (QUI) and cabergoline (CAB) are dopamine agonists recently introduced for the treatment of hyperprolactinemia. In the present study, these drugs have been compared in terms of effectiveness and tolerability. Twenty patients (18 females and 2 males) with hyperprolactinemia (8 with microprolactinomas, 6 with idiopathic hyperprolactinemia and 6 with empty sella turcica syndrome) were treated with oral QUI (75 microg once daily) and CAB (0,5 mg twice weekly), in a randomized cross-over trial with placebo between both drugs. Each drug was administered for 12 weeks, separated by other 12 weeks with placebo. PRL levels decreased with both drugs at 2 or 4 weeks of starting the treatment, without differences between both drugs at weeks 4, 8 and 12. At week 12, normal PRL levels (<20 ng/ml) were attained in 90% patients with CAB and only in 75% patients with QUI (p<0.05). After discontinuation of treatment, significant increase in serum PRL was higher after QUI withdrawal than after CAB. Clinical efficacy of both treatments was similar in terms of improvement amenorrhea, oligomenorrhea, galactorrhea, and impotence. All patients completed both cycles of treatment, and the most frequent side-effects were nausea, headache and dizziness, without significant differences between CAB (30%) and QUI (55%). Our study indicates that, at the doses employed here, CAB showed a high percentage of patients with normal PRL at the end of treatment and long-lasting efficacy in the levels of PRL. Clinical response and side-effects were similar in both drugs.

The effect of quinagolide and cabergoline, two selective dopamine receptor type 2 agonists, in the treatment of prolactinomas

OBJECTIVE

To compare effectiveness and tolerability of quinagolide (CV 205-502) and cabergoline (CAB) treatments in 39 patients with prolactinoma.

STUDY DESIGN

All 39 patients were treated first with quinagolide for 12 months and then with cabergoline for 12 months. A wash-out period was performed in all patients after 12 months of both treatments in order to evaluate recurrence of hyperprolactinaemia.

PATIENTS

Twenty-three patients with microprolactinoma (basal serum PRL levels 1620-18750 mU/l) and 16 patients with macroprolactinoma (basal serum PRL levels 4110-111000 mU/l), previously shown to be intolerant of bromocriptine. All patients had gonadal failure and 11 patients with macroprolactinoma had visual field defects. Five patients with macro- and one with microprolactinoma had previously undergone surgery.

STUDY PROTOCOL

The starting doses of quinagolide and CAB were 0.075 mg/day and 0.5 mg/week, respectively, subsequently increased up to 0.6 mg once daily and 1.5 mg twice weekly, respectively. Serum PRL levels were measured monthly for the first 3 months and then quarterly for 12 months. PRL levels were assayed weekly for the first month and then monthly during the wash-out period. Tumour shrinkage was evaluated by serial magnetic resonance imaging (MRI) studies of the hypothalamus-pituitary region at study entry and after 6 and 12 months of both treatments in micro- and macroprolactinomas.

RESULTS

After 12 months of quinagolide treatment, serum PRL levels normalized in all 23 patients with microprolactinoma (100%) and in 14 out of 16 with macroprolactinoma (87.5%). A tumour volume reduction of greater than 80% was documented by MRI studies in five of 23 (21.7%) patients with microprolactinoma and in four of 16 (25%) with macroprolactinoma. All patients had recurrence of hyperprolactinaemia after 15-60 days withdrawal of quinagolide treatment. However, before starting CAB treatment basal PRL levels were significantly lower than before quinagolide treatment both in microprolactinomas (4667.4 +/- 714.7 vs. 2636.1 +/- 262.3 mU/l, P = 0.006) and in macroprolactinomas (24853.1 +/- 7566.7 vs. 3576.6 +/- 413.0 mU/l, P = 0.013). After 12 months of CAB treatment, serum PRL levels normalized in 22 out of 23 patients with microprolactinoma (95.6%) and in 14 out of 16 with macroprolactinoma (87.5%). No difference in PRL nadir was found after quinagolide and CAB treatments both in micro 174.6 +/- 30.6 vs. 169.8 +/- 37.9 mU/l, P = 0.5) and in macroprolactinomas (277.5 +/- 68.4 vs. 341.8 +/- 95.2 mU/l, P = 0.6). A tumour volume reduction of greater than 80% was documented by MRI studies in seven other patients with microprolactinoma (30.4%) and in five other patients with macroprolactinoma (31.2%). After CAB treatment, further tumour shrinkage ranging 4-40% and 2-70% was observed in 12 micro- and seven macroprolactinomas, respectively. The percentage of tumour shrinkage after CAB was significantly higher than that observed after quinagolide in microprolactinomas (48.6 +/- 9.5 vs. 26.7 +/- 4. 5%, P = 0.046) but not in macroprolactinomas (47.0 +/- 10.6 vs. 26.8 +/- 8.4%, P = 0.2). The withdrawal from CAB treatment, induced an increase in serum PRL levels in all macroprolactinomas between 15 and 30 days, in 15 out of 23 microprolactinoma after 30 days, and in four patients after 2-4 months. In the remaining four patients serum PRL levels remained normal after 12 months of CAB withdrawal. Both compounds were tolerated satisfactorily by all patients. In the first week of quinagolide treatment, 12 patients reported nausea and postural hypotension, which spontaneously disappeared during the second-third week of treatment. None of the 39 patients reported side-effects during CAB treatment.

CONCLUSIONS

Both quinagolide and CAB treatments, induced the normalization of serum PRL levels in the great majority of patients with prolactinoma. Tumour shrinkage was recorded in 22-25% of patients after quinagolide and in 30-31% after CAB treatment

Clinical management of prolactinomas

Prolactinomas are benign, sporadic pituitary tumours that typically present with amenorrhoea and galactorrhoea in women, and hypogonadism and space-occupying effects in men. Hyperprolactinaemic hypogonadism in either sex is associated with reduced bone mineral density, which may be progressive and only partially reversible. For most microprolactinomas, dopamine agonists are the treatment of choice, achieving normoprolactinaemia and restoring gonadal function in 80-90% of cases. Trans-sphenoidal surgery is curative in 60%, but may be complicated by hypopituitarism and is usually reserved for patients with dopamine agonist intolerance or resistance. A subgroup of patients with small tumours, mild symptoms and normal gonadal function may be monitored without specific treatment--the risk of tumour expansion is small. Macroprolactinomas should be treated medically, dopamine agonists controlling prolactin secretion and achieving significant tumour shrinkage in 80% of cases, whereas surgery is curative in only a quarter. Cabergoline is the dopamine agonist of choice in most situations, being better tolerated and more effective than bromocriptine. Quinagolide is an effective alternative. Dopamine agonist withdrawal or dose reduction should be considered after 2-5 years therapy. Oestrogens may be used with caution in women with prolactinomas.

Treatment of androgen excess in females: yesterday, today and tomorrow

Hirsutism, acne and androgenic alopecia represent, in females, some of the manifestations of the clinical spectrum of hyperandrogenism. These pictures represent not only cosmetic damage, but also a source of remarkable psychological distress. Often hirsutism is regarded as presumptive evidence of a lack of femininity. The major diagnostic concern is to exclude an ovarian or adrenal androgen-secreting tumor, a congenital hyperplasia or polycystic ovary disease. Ethnic background should be taken into account together with the progression of the symptoms. Following the etiology, surgery and exogenous glucocorticoids or inhibition of gonadotropin secretion have to be carefully chosen in the management of different kinds of hyperandrogenism. Several pharmacologic agents have recently shown the ability to block the androgen receptors at target organ sites, thus allowing a specific antiandrogenic treatment. In some cases cosmetic measures could be of great value. Obesity accompanied by hyperinsulinemia can represent the main cause of ovary androgen hypersecretion; therefore a reduced body weight and muscle activity represent the basis of any treatment. Some other drugs, such as long-acting analogs of somatostatin, could be considered among possible drugs for the future. The aim of this article is to provide an appraisal of what is presently known about the regulation of hair growth, the various causes of excessive androgen secretion and the current methods to solve, safely, this important feminine clinical problem.