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

In the last decade, the treatment of macroprolactinomas has been significantly improved by the introduction in the clinical practice of new 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 micrograms/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 micrograms/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 micrograms/l. CT and/or MRI scans were performed before and during treatment to evaluate tumor shrinkage. Data are presented as Mean +/- SD.

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.

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.