Chronic treatment with parlodel LAR of patients with prolactin-secreting tumours. Different responsiveness of micro- and macroprolactinomas

Treatment of hyperprolactinemia: a systematic review and meta-analysis

BACKGROUND

Hyperprolactinemia is a common endocrine disorder that can be associated with significant morbidity. We conducted a systematic review and meta-analyses of outcomes of hyperprolactinemic patients, including microadenomas and macroadenomas, to provide evidence-based recommendations for practitioners. Through this review, we aimed to compare efficacy and adverse effects of medications, surgery and radiotherapy in the treatment of hyperprolactinemia.

METHODS

We searched electronic databases, reviewed bibliographies of included articles, and contacted experts in the field. Eligible studies provided longitudinal follow-up of patients with hyperprolactinemia and evaluated outcomes of interest. We collected descriptive, quality and outcome data (tumor growth, visual field defects, infertility, sexual dysfunction, amenorrhea/oligomenorrhea and prolactin levels).

RESULTS

After review, 8 randomized and 178 nonrandomized studies (over 3,000 patients) met inclusion criteria. Compared to no treatment, dopamine agonists significantly reduced prolactin level (weighted mean difference, -45; 95% confidence interval, -77 to -11) and the likelihood of persistent hyperprolactinemia (relative risk, 0.90; 95% confidence interval, 0.81 to 0.99). Cabergoline was more effective than bromocriptine in reducing persistent hyperprolactinemia, amenorrhea/oligomenorrhea, and galactorrhea. A large body of noncomparative literature showed dopamine agonists improved other patient-important outcomes. Low-to-moderate quality evidence supports improved outcomes with surgery and radiotherapy compared to no treatment in patients who were resistant to or intolerant of dopamine agonists.

CONCLUSION

Our results provide evidence to support the use of dopamine agonists in reducing prolactin levels and persistent hyperprolactinemia, with cabergoline proving more efficacious than bromocriptine. Radiotherapy and surgery are useful in patients with resistance or intolerance to dopamine agonists.

Invasive giant prolactinoma with loss of therapeutic response to cabergoline: expression of angiogenic markers

The present study reports the case of a 70-year-old Caucasian man who was referred to the Military Hospital of Buenos Aires for evaluation of a giant sellar-extrasellar mass with extension in the right temporal lobe and compression of the third ventricle. Patient was initially responsive to cabergoline with reduction of prolactin levels and shrinkage of tumor burden for at least 36 months. Thereafter, prolactin levels and tumor size increased even though cabergoline dosage was increased. Transcraneal surgery was performed at 56 months of treatment. Prolactin levels and tumor proliferation did not subside and the patient died 14 months later. High GH and IGF-I levels were observed in the late stages of tumor development, with no evidence of acromegalic features. Immunohistochemistry of the excised tumor revealed strong immunoreactivity for VEGF and FGF-2, two potent angiogenic factors, and CD31 (an endothelial marker) indicating high vascularization of the adenoma.

Gamma knife radiosurgery for prolactinomas

Object. In this retrospective investigation the authors examined the results of gamma knife radiosurgery (GKS) for tumor remnants after unsuccessful open surgery and medical treatment in 20 patients with prolactinomas. Particular attention is paid to a possible radioprotective action of dopamine agonists similar to the action of octreotide in acromegaly.

Methods. Twenty patients with prolactinomas were followed after GKS. Five patients were treated successfully; their prolactin (PRL) levels dropped into the normal range and dopaminergic drugs could be discontinued. Two spontaneous pregnancies were observed and 11 patients experienced improvement. Improvement was defined as normal PRL levels with the continued possibility of reduced medical treatment or a substantially reduced medical treatment dose with some degree of hyperprolactinemia maintained. The treatment failed in three patients who experienced no improvement. Patients treated with dopaminergic drugs during GKS did significantly less well in comparison with the untreated group when a cumulative distribution function (Kaplan—Meier estimate) was used.

Conclusions. The results of GKS for prolactinomas in this investigation are better than the results published by others. This may be an effect of case selection because there were no “salvage cases” in our group of patients. Because a dopamine agonist seemed to induce radioprotection in this series, it is suggested that GKS be performed during an intermission in drug therapy when the dopamine agonist is discontinued.

Treatment with long acting repeatable bromocriptine (Parlodel-LAR*) in patients with macroprolactinomas: long-term study in 29 patients

The aim of the study was to evaluate the short term and long-term effects of long acting repeatable bromocriptine (= Parlodel-LAR*) in patients with macroprolactinomas. Twenty-nine patients (15 men and 14 women) aged 42 +/- 2.7 (M +/- SEM) years were injected with Parlodel-LAR* every 4 weeks during 3.3 +/- 0.3 years. The starting dose was 50 mg/injection, then it was increased to 100 mg in 11 patients and 150 mg in 9 patients. PRL levels decreased in all but one patient 4 weeks after the first injection (270 +/- 59 vs 934 +/- 210 ng/ml, p < 0.001), then became less than 20 ng/ml in 20/29 (69%) patients and finally became undetectable or low in 13/29 (45%) patients. Visual field defects were present in 12/29 patients before treatment. In 11/12 patients, treatment with Parlodel-LAR* resulted in an improvement and complete correction of visual field defects was observed in 8/12 patients. Adenoma size (2.5 +/- 0.2 cm before treatment) was reduced by at least 20% in 24/29 (83%) patients. Disappearance of adenoma was observed on CT scan in 8/29 (28%) patients after 28.7 +/- 5.3 months of treatment. Minor side effects occurred in 20 patients after the first injection then disappeared in 18 patients within the following 6 months of treatment. One patient had rhinorrhea after 3 months of treatment. Treatment with Parlodel-LAR* results in beneficial short-term effects (with rapid correction of recent onset visual field defects) and long-term effects (which can include complete disappearance of adenoma on CT scan evaluation) in patients with macroprolactinomas.

Relative resistance of a macroprolactinoma to bromocriptine therapy during pregnancy

A woman presented with a pituitary macroadenoma with extensive suprasellar extension. Her initial response to bromocriptine therapy was good, allowing subsequent trans-sphenoidal surgical treatment. The tumor grew during pregnancy despite continued bromocriptine therapy, but it returned to prepregnancy size postdelivery. There have been conflicting reports regarding the growth of pituitary tumors in pregnancy. Most recognize that some growth may occur, but only a small percentage of patients are reported to become symptomatic from the growth. Resistance to bromocriptine has been reported in non-pregnant patients. Patients who have had surgery or radiation therapy and did not receive bromocriptine treatment during pregnancy have been reported to have symptomatic growth of their residual tumor. This case demonstrates an unusual tumor that became resistant to bromocriptine during pregnancy, but whose sensitivity to the drug returned postdelivery.

No difference between micro- and macroprolactinomas in the prolactin responsiveness to metoclopramide and dopamine administration

Differences between micro- and macroprolactinomas, as regards the prolactin secretory pattern in response to pharmacological challenges, have been reported in in vivo and in vitro models, and interpreted as being due to different dopaminergic regulation of prolactin release. In 32 patients with prolactin-secreting tumors, 19 with microprolactinomas and 13 with macroprolactinomas, and ten healthy volunteers, we evaluated the prolactin secretion in response to pharmacological manipulations of central dopaminergic tone. To this end, three tests were performed, in random order: (1) 4-h saline infusion; (2) 10 mg metoclopramide as i.v. bolus; (3) 4-h dopamine infusion (0.01 microgram/kg/min) with a 10-mg metoclopramide bolus given after the second hour of infusion. Dopamine infusion, compared to saline, caused a significant prolactin decrease in all the three groups of subjects, without significant difference between micro- and macroprolactinoma patients. In prolactinoma patients, administration of metoclopramide induced a significant rise in plasma prolactin which, however, was significantly lower than the one displayed by controls. Again, no difference was observed between the two groups of hyperprolactinemic patients. Dopamine infusion induced a significant and comparable increase in the prolactin response to metoclopramide in micro- and macroprolactinoma patients, while it was ineffective in control subjects. In conclusion, no differences appear to exist between micro- and macroprolactinoma patients as regards the prolactin secretory pattern during pharmacological modifications of the dopaminergic tone. A central dopaminergic defect and an increased prolactin turnover with attendant reduction of the intracellular hormone pool may both be involved in the reduced prolactin release following provocative stimuli in patients with prolactinoma.

Effectiveness of a long-acting injectable form of bromocriptine in patients with prolactin and growth hormone secreting macroadenomas

OBJECTIVE

With the development of new long-acting depot preparations of bromocriptine (bromocriptine LAR), we investigated the effectiveness of intramuscular injections of long-acting bromocriptine in patients with prolactin and GH secreting macroadenomas.

STUDY DESIGN AND PATIENTS

Fourteen patients with PRL secreting (8 patients) and GH secreting (6 patients) macroadenomas were treated with monthly intramuscular injections of a long-acting and repeatable form of bromocriptine for 3-6 months. A 50-mg monthly dose was administered in the majority of patients with PRL secreting macroadenomas. A 100-mg monthly dose was administered in all patients with GH secreting macroadenomas.

MEASUREMENTS

Plasma PRL and/or GH levels were measured 6 and 12 hours after the first injection and then on days 1, 2, 14 and 28 after each injection, up to a maximum period of 6 months. Patients were hospitalized for 48 hours after each injection and were specifically questioned with respect to side-effects. Pituitary imaging with MRI or CT scans was performed in all patients before commencing treatment and was subsequently repeated in 5/8 patients with macroprolactinomas and 5/6 patients with GH secreting macroadenomas after the completion of a 6-month course of treatment.

RESULTS

In all patients with macroprolactinomas, serum PRL levels decreased significantly after their first 50-mg injection with nadir levels obtained by 24-48 hours post injection (12815 +/- 8704 vs 1480 +/- 1859 mU/l; mean +/- SD, P < 0.01). At their latest follow-up, on a 50-mg monthly dose, 4 patients developed normoprolactinaemia (PRL levels < 360 mU/l) while two patients demonstrated a significant reduction in serum PRL levels (70 and 87% or pretreatment values). In two patients, although a substantial decrement of serum PRL levels was achieved 12-24 hours post injection, serum PRL levels increased to pretreatment values by day 14 post injection. Both patients received a higher (100 mg) monthly dose which was partially effective in one patient. In two patients with GH secreting macroadenomas, a sustained decrease of elevated GH levels was observed; in two patients, while a substantial reduction of the elevated serum GH levels was achieved 12-24 hours after the first and subsequent injections, serum GH levels increased to pretreatment values by day 14 post injection; in two patients there was no effect on the elevated serum GH levels. Significant tumour shrinkage (24-50%) was observed in 5/5 patients with PRL secreting macroadenomas assessed at completion of a 6-month course of treatment. Significant tumour shrinkage was also documented in 2/5 acromegalics tested (29 and 46% respectively).

CONCLUSION

It is concluded that bromocriptine LAR is an effective treatment in the majority of patients with macroprolactinomas; it is also partially effective in some patients with GH secreting macroadenomas.

Long-acting injectable bromocriptine (Parlodel LAR) in the chronic treatment of prolactin-secreting macroadenomas

OBJECTIVE

To evaluate the efficacy and tolerability of Parlodel LAR (Sandoz, Basel, Switzerland), a long-acting injectable bromocriptine, in PRL-secreting macroadenomas.

DESIGN

Eleven patients with macroprolactinomas were studied in an academic environment in an open and prospective protocol. Ten patients were followed for 6 months and 8 for 1 year. Fifty to 200 mg IM of Parlodel LAR were administered every 28 days.

RESULTS

At the end of the 1st month, 64% of the patients had PRL suppression of > 75% of baseline values. After 1 year, 88% of the cases had PRL suppression of > 90%. Persistent PRL normalization was seen in three cases. Tumor shrinkage was seen in 64% of the patients on day 5, in 73% on day 28, and in 90% after 6 months of treatment. Early visual field improvement was seen in 83% of the cases. All patients had improvement of clinical symptoms.

CONCLUSION

Parlodel LAR is well tolerated and very effective in the long-term treatment of patients with PRL-secreting macroadenomas.