Comparison among different dopamine-agonists of new formulation in the clinical management of macroprolactinomas

Background: In the last decade, the treatment of macroprolactinomas has been significantly improved by the introduction in the clinical practice of few drugs with dopamine-agonist properties. In particular, the availability of different forms of bromocriptine (BRC) with long duration of action and slow absorption, suitable for injectable (BRC-LAR) or oral (BRC-SRO) administration, has allowed one to obtain a more constant bromocriptinemia than with standard BRC, thus reducing adverse reactions. Moreover, a selective action on dopamine D₂ receptors has been achieved using a new non-ergot derivative: the quinagolide (CV 205-502). The aim of this study was to evaluate the effects of BRC-LAR, BRC-SRO and CV 205-502 in 34 patients with macroprolactinoma. Protocol of the study: BRC-LAR was given at the monthly dose of 50-100 mg for 6-24 months to 8 patients whose PRL levels were 150-700 μg/l. BRC-SRO was given at the daily dose of 5-20 mg for 1-24 months to 10 patients whose PRL levels were 120-900 μg/l. CV 205-502 was given at the daily dose of 0.075-0.6 mg for 6-12 months to 16 patients whose PRL levels were 250-2,050 μg/l. CT and/or MRI scans were performed before and during treatment to evaluate tumor shrinkage. Data are presented as Mean ± SD. Results: Serum PRL levels normalized in 8/8 with BRC-LAR, 7/10 with BRC-SRO and 12/16 patients with CV 205-502. A significant shrinkage of tumor mass was obtained in 7/8 with BRC-LAR, 9/10 with BRC-SRO and 16/16 patients with CV 205-502, with consequent improvement of visual-field defects. Overall, the drugs were rather well tolerated: no patient stopped BRC-LAR or BRC-SRO and only 2 stopped CV 205-502. In particular, nausea, vomiting, headache, hypotension that disappeared spontaneously were observed in 5/8 with BRC-LAR, 4/10 with BRC-SRO and 4/16 with CV 205-502. Conclusions: The medical approach with long-acting BRC preparations and CV 205-502 which selectively binds D₂ receptors allows one to obtain rapid normalization of PRL levels and shrinkage of macroprolactinomas in a large series of patients. These drugs are rather well tolerated also by patients proven to be untolerant to standard BRC.