Oral and injectable long-lasting bromocriptine preparations in hyperprolactinemia: comparison of their prolactin lowering activity, tolerability and safety

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.

Hyperprolactinemia

Prolactin (PRL) is an anterior pituitary hormone which has its principle physiological action in initiation and maintenance of lactation. In human reproduction, pathological hyperprolactinemia most commonly presents as an ovulatory disorder and is often associated with secondary amenorrhea or oligomenorrhea. Galactorrhea, a typical symptom of hyperprolactinemia, occurs in less than half the cases. Out of the causes of hyperprolactinemia, pituitary tumors may be responsible for almost 50% of cases and need to be investigated especially in the absence of history of drug induced hyperprolactinemia. In women with hyperprolactinemic amenorrhea one important consequence of estrogen deficiency is osteoporosis, which deserves specific therapeutic consideration. Problem in diagnosing and treating hyperprolactinemia is the occurrence of the ‘big big molecule of prolactin’ that is biologically inactive (called macroprolactinemia), but detected by the same radioimmunoassay as the biologically active prolactin. This may explain many cases of very high prolactin levels sometimes found in normally ovulating women and do not require any treatment. Dopamine agonist is the mainstay of treatment. However, presence of a pituitary macroadenoma may require surgical or radiological management.

Evaluation of a novel vaginal bromocriptine mesylate formulation: A pilot study

Because of the frequent side effects found with oral bromocriptine, we created two formulas of vaginal bromocriptine suppositories to compare with vaginal application of bromocriptine tablets. The formula containing bromocriptine and a releasing agent (Pluronic F127) showed an increased dissolution rate, 39-fold greater than that of the pure drug alone, and subsequently was effective in lowering serum prolactin.

Positive response to compound CV 205-502 in hyperprolactinemic patients resistant to or intolerant of bromocriptine

The clinical effects of CV 205-502, a potent and non-ergot-derived dopamine agonist, were investigated in 24 selected patients with hyperprolactinemia previously treated with standard oral bromocriptine, the slow-release oral form of bromocriptine (BRC-SRO) and/or the long-acting injectable form of bromocriptine (BRC-LAR); 14 were chosen because of their resistance to treatment and ten because they were intolerant of the different forms of bromocriptine. A macroprolactinoma was present in seven patients and a microprolactinoma in ten, whereas seven had no radiological images of a pituitary tumor and were classified as having non-tumoral hyperprolactinemia. All the 24 patients were treated with CV 205-502 at a daily dose of 0.075-0.6 mg for 3-12 months. All the patients had gonadal dysfunction and galactorrhea. Basal serum prolactin values ranged from 70 to 1677 ng/ml. CV 205-502 was effective in 11 of the 14 patients resistant bromocriptine, BRC-SRO and BRC-LAR; serum prolactin levels became normal within 6 months and a tumor shrinkage was obtained in five of the seven macroprolactinomas. In general, the drug was effective and well tolerated. Only three patients (two resistant and one intolerant) manifested nausea, vomiting and postural hypotension. In conclusion, this study shows that CV 205-502 is effective in bromocriptine-resistant hyperprolactinemic patients. Furthermore, CV 205-502 has insignificant and tolerable side-effects in patients intolerant of bromocriptine. CV 205-502 can, therefore, be considered a useful and effective drug, and an interesting therapeutic alternative to the ergot-derived dopamine-agonist drugs in use today.

CV 205-502 in the treatment of tumoral and non-tumoral hyperprolactinemic states

CV 205-502 (octahydrobenzol[g]quinoline), a non-ergot dopamine agonist drug, was administered to 40 patients with hyperprolactinemic syndrome: 16 patients with macroprolactinoma, 14 with microprolactinoma and 10 with non-tumoral hyperprolactinemia. Twenty-four out of 40 patients had previously been treated by surgery and/or bromocriptine, with variable results. All had gonadal dysfunction and 22 patients had galactorrhea. Eight patients with macroprolactinoma had defects of the visual field. Pre-treatment serum PRL levels ranged from 60 to 2050 micrograms/l. The daily dose of CV 205-502 used in this trial ranged from 0.075 to 0.600 mg. After 6-12 months of treatment, serum PRL level decreased in all the patients reaching normoprolactinemia in 31 of them (77.5%) who demonstrated restoration of menses and disappearance of galactorrhea. The remaining nine patients (22.5%) had only a decrease of PRL levels without reaching normoprolactinemia and without any clinical effect. In 12 out of 16 patients with macroprolactinoma not previously surgically treated, a significant tumor shrinkage was shown by means of Computed Tomography and/or Magnetic Resonance Imaging. The disappearance of visual defects was obtained in four out of eight patients. CV 205-502 was tolerated satisfactorily: mild side-effects occurred in four patients in the first week of treatment and spontaneously disappeared, whereas six patients (15%) needed to withdraw the therapy after 6 months because of side-effects. In conclusion CV 205-502 is a potent and well-tolerated drug in the treatment of tumoral and non-tumoral hyperprolactinemic states and is an effective alternative to other dopamine agonists in use today.